Volume 01 - Properties and Selection Irons, Steels, and High-Performance Alloys Part 7 potx

Fig. 1
Properties of cast carbon steels as a function of carbon content and heat treatment. (a) Tensile strength
and reduction of area. (b) Yield strength and elongation. (c) Brinell hardness. (d) Charpy V-
notch impact
energy
Low-alloy steels contain, in addition to carbon, alloying elements up to a total alloy content of 8%. Cast steels
containing more than the following amounts of a single alloying element are considered low-alloy cast steel:

Element
Amount, %

Manganese
1.00
Silicon
0.80
Nickel
0.50
Copper
0.50
Chromium
0.25
Molybdenum

0.10
Vanadium
0.05
Tungsten 0.05

Aluminum, titanium, and zirconium are used for the deoxidation of low-alloy steels. Of these elements, aluminum is used
most frequently because of its effectiveness and low cost.

Numerous types of cast low-alloy steel grades exist to meet the specific requirements of the end-use, such as structural
strength and resistance to wear, heat, and corrosion. The designations of the American Iron and Steel Institute (AISI) and
the Society of Automotive Engineers (SAE) have historically been used to identify the various types of steel by their
principal alloy content. Cast steels, however, do not precisely follow the compositional ranges specified by AISI and SAE
designations for wrought steels. In most cases, the cast steel grades contain 0.30 to 0.65% Si and 0.50 to 1.00% Mn,
unless otherwise specified. The principal low-alloy cast steel designations, their AISI and SAE equivalents, and their
alloy type are:

Cast steel

designation

Nearest
wrought
equivalent

Alloying elements
1300 1300
Manganese
8000, 8400 8000, 8400

Manganese, molybdenum
80B00 80B00
Manganese, molybdenum, boron
2300 2300
Nickel
8600, 4300 8600, 4300

Nickel, chromium, molybdenum
9500 9500

Manganese, nickel, chromium, molybdenum

4100 4100 Chromium, molybdenum

The 8000, 8400, 2300, and 9500 alloy types are used extensively as cast steels. There are additional alloy types that are
infrequently specified as cast steels, that is, 3100 (nickel-chromium), 3300 (nickel-chromium), 4000 (molybdenum), 5100
(chromium), 6100 (chromium-vanadium), 4600 (nickel-molybdenum), and 9200 (silicon). Further information on the
elements used in alloy steel castings is provided in the section "Low-Alloy Cast Steels" of this article.
Specifications. Steel castings are usually purchased to meet specified mechanical properties, with some restrictions on
chemical composition. Tables 1 and 2 list the requirements given in various specifications of the American Society of
Testing and Materials (ASTM) and in SAE J435c. Table 1 primarily lists carbon steel castings (with some comparable
low-alloy types), while Table 2 lists several low-alloy cast steels and some cast steels with chromium contents up to
10.0%.
Table 1 Summary of specification requirements for various carbon steel castings
Unless otherwise noted, all the grades listed in this table are restricted to a phosphorus content of 0.40% max and a sulfur content of
0.045% max.
Tensile
strength
(a)

Yield
strength
(a)


Chemical
composition
(b)
, %
Class

or
grade
MPa ksi MPa

ksi

Minimum

elongation

in 50 mm

(2 in.), %
Minimum

reduction
in
area, %
C Mn Si
Other
requirements
Condition or specific
application
ASTM A 27: carbon steel castings for general applications
N-1 . . . . . . . . . . .
.
. . . . . . 0.25
(c)

0.75
(c)


0.80

0.06% S,
0.05% P
Chemical analysis only
N-2 . . . . . . . . . . .
.
. . . . . . 0.35
(c)


0.60
(c)


0.80

0.06% S,
0.05% P
Heat treated but not
mechanically tested
U60-30

415 60 205 30 22 30 0.25
(c)

0.75
(c)


0.80

0.06% S,
0.05% P
Mechanically tested but
not heat treated
60-30 415 60 205 30 24 35 0.30
(c)


0.60
(c)


0.80

0.06% S,
0.05% P
Heat treated and
mechanically tested
65-35 450 65 240 35 24 35 0.30
(c)


0.70

(c)


0.80

0.06% S,
0.05% P
Heat treated and
mechanically tested
70-36 485 70 250 36 22 30 0.35
(c)


0.70
(c)


0.80

0.06% S,
0.05% P
Heat treated and
mechanically tested
70-40 485 70 275 40 22 30 0.25
(c)


1.20
(c)

0.80

0.06% S,
0.05% P
Heat treated and
mechanically tested
ASTM A 148: carbon steel castings for structural applications
(d)

80-40 550 80 275 40 18 30
(e)

(e)

(e)
0.06% S,
0.05% P
Composition and heat
treatment necessary to
achieve specified
mechanical properties
80-50 550 80 345 50 22 35
(e)

(e)

(e)
0.06% S,
0.05% P

Composition and heat
treatment necessary to
achieve specified
mechanical properties
90-60 620 90 415 60 20 40
(e)

(e)

(e)
0.06% S,
0.05% P
Composition and heat
treatment necessary to
achieve specified
mechanical properties
105-85 725 105

585 85 17 35
(e)

(e)

(e)
0.06% S,
0.05% P
Composition and heat
treatment necessary to
achieve specified
mechanical properties

SAE J435c: see Table 2 for alloy steel castings specified in SAE J435c
0022 . . . . . . . . . . .
.
. . . . . . 0.12-
0.22
0.50-
0.90
0.60

187 HB max
Low carbon steel
suitable for carburizing
0025 415 60 207 30 22 30 0.25
(c)


0.75
(c)


0.80

187 HB max
Carbon steel welding
grade
0030 450 65 241 35 24 35 0.30
(c)


0.70

(c)


0.80

131-187 HB
Carbon steel welding
grade
0050A 585 85 310 45 16 24 0.40-
0.50
0.50-
0.90
0.80

170-229 HB
Carbon steel medium-
strength grade
0050B 690 100

485 70 10 15 0.40-
0.50
0.50-
0.90
0.80

207-225 HB
Carbon steel medium-
strength grade
080 550 80 345 50 22 35 . . . . . . . . . 163-207 HB
Medium-strength low-

alloy steel
090 620 90 415 60 20 40 . . . . . . . . . 187-241 HB
Medium-strength low-
alloy steel
HA,
HB,
HC
(f)

. . . . . . . . . . .
.
. . . . . . 0.25-
0.34
(f)

(f)
See Fig. 2.
Hardenability grades
(Fig. 2)
ASTM A 216: carbon steel castings suitable for fusion welding and high-temperature service
WCA 415-
585
60-
85
205 30 24 35 0.25 0.70
(c)


0.60

(g)

Pressure-containing
parts
WCB 485-
655
70-
95
250 36 22 35 0.30 1.00
(c)


0.60

(g)

Pressure-containing
parts
WCC 485-
655
70-
95
275 40 22 35 0.25 1.20
(c)


0.50

(g)

Pressure-containing
parts
Other ASTM cast steel specifications with carbon steel grades
(h)

A 352-
LCA
415-
585
60-
85
205 30 24 35 0.25 0.70
(c)


0.60

(g)(i)(j)

Low-temperature
applications
A 352-
LCB
450-
620
65-
90
240 35 24 35 0.30 1.00 0.60

(g)

,
(j)
,
(k)

Low-temperature
applications
A 356-
grade 1

485 70 250 36 20 35 0.35 0.70
(c)


0.60

0.035% P max,
0.030 S max
Castings for valve
chests, throttle valves,
and other heavy-walled
components for steam
turbines
A 757-
A1Q
450 65 240 35 24 35 0.30 1.00 0.60

(j)
,
(k)

,
(l)
Castings for pressure-
containing applications
at low temperatures

(a)
Where a single value is shown, it is a minimum.
(b)
Where a single value is shown, it is a maximum.
(c)
For each reduction of 0.01% C below the maximum specified, an increase of 0.04% Mn above the maximum specified is permitted up to the
maximums given in the applicable ASTM specifications.
(d)
Grades may also include low-alloy steels; see Table 2 for the stronger grades of ASTM A 148.
(e)
Unless specified by purchaser, the compositions of cast steels in ASTM A 148 are selected by the producer in order to achieve the specified
mechanical properties.
(f)
Purchased on the basis of hardenability, with manganese and other elements added as required.
(g)
Specified residual elements include 0.30% Cu max, 0.50% Ni max, 0.50% Cr max, 0.20% Mo max, and 0.03% V max, with the total residual
elements not exceeding 1.00%.
(h)
These ASTM specifications also include alloy steel castings for the general type of applications listed in the Table.
(i)
Testing temperature of -32 °C (-25 °F).
(j)
Charpy V-notch impact testing at the specified test temperature with an energy value of 18 J (13 ft · lbf) min for two specimens and an average
of three.

(k)
Testing temperature of -46 °C (-50 °F).
(l)
Specified residual elements of 0.03% V, 0.50% Cu, 0.50% Ni, 0.40% Cr, and 0.25% Mo, with total amount not exceeding 1.00%. Sulfur and
phosphorus content, each 0.025% max

Table 2 Summary of specification requirements for various alloy steel castings with chromium contents up
to 10%
Tensile
strength
(b)

Yield
strength
(b)

Composition
(c)
,%
Material
class
(a)

MPa ksi MPa

ksi
Minimum

elongation

in 50 mm

(2 in.), %
Minimum

reduction

in area,
%
C Mn Si Cr Ni Mo
Other
ASTM A 148: steel castings for structural applications
(d)

115-95 795 115 655 95 14 30 . . . . . . . . . . . . . . . . . .
(e)

135-125 930 135 860 125

9 22 . . . . . . . . . . . . . . . . . .
(e)

150-135 1035 150 930 135

7 18 . . . . . . . . . . . . . . . . . .
(e)

160-145 1105 160 1000

145

6 12 . . . . . . . . . . . . . . . . . .
(e)

165-150 1140 165 1035

150

5 20 . . . . . . . . . . . . . . . . . .
(f)

165-150L

1140 165 1035

150

5 20 . . . . . . . . . . . . . . . . . .
(f)

210-180 1450 210 1240

180

4 15 . . . . . . . . . . . . . . . . . .
(f)

210-180L

1450 210 1240

180

4 15 . . . . . . . . . . . . . . . . . .
(f)

260-210 1795 260 1450

210

3 6 . . . . . . . . . . . . . . . . . .
(f)

260-210L

1795 260 1450

210

3 6 . . . . . . . . . . . . . . . . . .
(f)

SAE J435c: see Table 1 for the carbon steel castings specified in SAE J435c
(g)

0105 725 105 586 85 17 35 . . . . . . . . . . . . . . . . . .
(h)

0120 827 120 655 95 14 30 . . . . . . . . . . . . . . . . . .
(h)

0150 1035 150 862 125

9 22 . . . . . . . . . . . . . . . . . .
(h)

0175 1207 175 1000

145

6 12 . . . . . . . . . . . . . . . . . .
(h)

ASTM A 217: alloy steel castings for pressure-containing parts and high-temperature service
WC1 450-
620
65-
90
240 35 24 35 0.25 0.50-
0.80
0.60 0.35
(i)
0.50
(i)
0.45-
0.65
(i)(j)

WC4 485-
655

70-
95
275 40 20 35 0.20 0.50-
0.80
0.60 0.50-
0.80
0.70-
1.10
0.45-
0.65
(j)
,
(k)

WC5 485-
655
70-
95
275 40 20 35 0.20 0.40-
0.70
0.60 0.50-
0.90
0.60-
1.00
0.90-
1.20
(j)
,
(k)

WC6 485-
655
70-
95
275 40 20 35 0.20 0.50-
0.80
0.60 1.00-
1.50
0.50
(i)
0.45-
0.65
(i)
,
(j)

WC9 485-
655
70-
95
275 40 20 35 0.18 0.40-
0.70
0.60 2.00-
2.75
0.50
(i)
0.9-
1.20
(i)
,

(j)

WC11 550-
725
80-
105
345 50 18 45 0.15-
0.21
0.50-
0.80
0.30-
0.60
1.00-
1.75
0.50
(i)
0.45-
0.65
(i)
,
(l)

C5 620-
795
90-
115
415 60 18 35 0.20 0.40-
0.70
0.75 4.00-
6.50

0.50
(i)
0.45-
0.65
(i)
,
(j)

C12 620-
795
90-
115
415 60 18 35 0.20 0.35-
0.65
1.00 8.00-
10.00
0.50
(i)
0.90-
1.20
(i)
,
(j)

ASTM A 389: alloy steel castings (NT) suitable for fusion welding and pressure-containing parts at high temperatures
C23 485 70 275 40 18 35 0.20 0.30-
0.80
0.60 1.00-
1.50
. . . 0.45-

0.65
(h)
,
(m)

C24 550 80 345 50 15 35 0.20 0.30-
0.80
0.60 1.00-
1.25
. . . 0.90-
1.20
(h)
,
(m)

ASTM A 487: alloy steel castings (NT or QT) for pressure-containing parts at high temperatures
1A (NT) 585-
760
85-
110
380 55 22 40 0.30 1.00 0.80 0.35
(n)
0.50
(n)
0.25
(n)
,
(o)

0.5Cu

(h)
,
(n)

2B (QT) 620-
795
90-
115
450 65 22 45 0.30 1.00 0.80 0.35
(n)
0.50
(n)
0.25
(n)
,
(o)

0.5Cu
(h)
,
(n)

1C (NT
or QT)
620 90 450 65 22 45 0.30 1.00 0.80 0.35
(n)
0.50
(n)
0.25
(n)

,
(o)

0.5Cu
(h)
,
(n)

2A (NT) 585-
760
85-
110
365 53 22 35 0.30 1.10-
1.40
0.80 0.35
(i)
0.50
(i)
0.10-
0.30
(i)
,
(p)

2B (QT) 620-
795
90-
115
450 65 22 40 0.30 1.10-
1.40

0.80 0.35
(i)
0.50
(i)
0.10-
0.30
(i)
,
(p)

2C (NT
or QT)
620 90 450 65 22 40 0.30 1.10-
1.40
0.80 0.35
(i)
0.50
(i)
0.10-
0.30
(i)
,
(p)

4A (NT
or QT)
620-
795
90-
115

415 60 20 40 0.30 1.00 0.80 0.40-
0.80
0.40-
0.80
0.15-
0.30
(k)
,
(p)

4B (QT) 725-
895
105-
130
585 85 17 35 0.30 1.00 0.80 0.40-
0.80
0.40-
0.80
0.15-
0.30
(k)
,
(p)

4C (NT
or QT)
620 90 415 60 20 40 0.30 1.00 0.80 0.40-
0.80
0.40-
0.80

0.15-
0.30
(k)
,
(p)

4D (QT) 690 100 515 75 17 35 0.30 1.00 0.80 0.40-
0.80
0.40-
0.80
0.15-
0.30
(k)
,
(p)

4E (QT) 795 115 655 95 15 35 0.30 1.00 0.80 0.40-
0.80
0.40-
0.80
0.15-
0.30
(k)
,
(p)

6A (NT) 795 115 550 80 18 30 0.38 1.30-
1.70
0.80 0.40-
0.80

0.40-
0.80
0.30-
0.40
(k)
,
(p)

6B (QT) 825 120 655 95 15 35 0.38 1.30-
1.70
0.80 0.40-
0.80
0.40-
0.80
0.30-
0.40
(k)
,
(p)

7A
(QT)
(q)

795 115 690 100

15 30 0.20 0.60-
1.00
0.80 0.40-
0.80

0.70-
1.00
0.40-
0.60
(k)
,
(p)
,
(r)

8A (NT) 585-
760
85-
110
380 55 20 35 0.20 0.50-
0.90
0.80 2.00-
2.75
. . . 0.90-
1.10
(k)
,
(p)

8B (QT) 725 105 585 85 17 30 0.20 0.50-
0.90
0.80 2.00-
2.75
. . . 0.90-
1.10

(k)
,
(p)

8C (QT) 690 100 515 75 17 35 0.20 0.50-
0.90
0.80 2.00-
2.75
. . . 0.90-
1.10
(k)
,
(p)

9A (NT
or QT)
620 90 415 60 18 35 0.33 0.60-
1.00
0.80 0.75-
1.10
0.50
(i)
0.15-
0.30
(i)
,
(p)

9B (QT) 725 105 585 85 16 35 0.33 0.60-
1.00

0.80 0.75-
1.10
0.50
(i)
0.15-
0.30
(i)
,
(p)

9C (NT
or QT)
620 90 415 60 18 35
Composition same as 9A (NT or QT) but with a slightly higher
tempering temperature
9D (QT) 690 100 515 75 17 35 0.33 0.60-
1.00
0.80 0.75-
1.10
0.50
(i)
0.15-
0.30
(i)
,
(p)

10A (NT)

690 100 485 70 18 35 0.30 0.60-

1.00
0.80 0.55-
0.90
1.40-
2.00
0.20-
0.40
(k)
,
(p)

10B (QT) 860 125 690 100

15 35 0.30 0.60-
1.00
0.80 0.55-
0.90
1.40-
2.00
0.20-
0.40
(k)
,
(p)

11A (NT)

485-
655
70-

95
275 40 20 35 0.20 0.50-
0.80
0.60 0.50-
0.80
0.70-
1.10
0.45-
0.65
(p)
,
(s)

11B (QT) 725-
895
105-
130
585 85 17 35 0.20 0.50-
0.80
0.60 0.50-
0.80
0.70-
1.10
0.45-
0.65
(p)
,
(s)

12A (NT)

485-
655
70-
95
275 40 20 35 0.20 0.40-
0.70
0.60 0.50-
0.90
0.60-
1.00
0.90-
1.20
(p)
,
(s)

12B (QT) 725-
895
105-
130
585 85 17 35 0.20 0.40-
0.70
0.60 0.50-
0.90
0.60-
1.00
0.90-
1.20
(p)

,
(s)

13A (NT)

620-
795
90-
115
415 60 18 35 0.30 0.80-
1.10
0.60 0.40
(t)
1.40-
1.75
0.20-
0.30
(p)
,
(t)

13B (QT) 725-
895
105-
130
585 85 17 35 0.30 0.80-
1.10
0.60 0.40
(t)
1.40-

1.75
0.20-
0.30
(p)
,
(t)

14A (QT)

825-
1000
120-
145
655 95 14 30 0.55 0.80-
1.10
0.60 0.40
(t)
1.40-
1.75
0.20-
0.30
(p)
,
(t)

16A
(NT)
(u)

485-

655
70-
95
275 40 22 35 0.12
(v)
2.10
(v)
0.50 0.20
(s)
1.00-
1.40
0.10
(s)

(s)
,
(w)


(a)
NT, normalized and tempered; QT, quenched and tempered.
(b)
When a single value is shown, it is a minimum.
(c)
When a single value is shown, it is a maximum.
(d)
Unless specified by the purchaser, the compositions of cast steels in ASTM A 148 are selected by the producer and therefore may include
either carbon or alloy steels; see Table 1 for the lower-grade steels specified in ASTM A 148.
(e)
0.06% S (max), 0.05% P (max).

(f)
0.020% S (max, 0.020% P (max).
(g)
Similar to the cast steel in ASTM A 148.
(h)
0.045% S (max), 0.040% P (max).
(i)
When residual maximums are specified for copper, nickel, nickel, chromium, tungsten, and vanadium, their total content shall not exceed
1.00%.
(j)
0.050% Cu (max), 0.10% W (max), 0.045% S(max), 0.04% P (max).
(k)
When residual maximums are specified for copper, nickel, chromium, tungsten, and vanadium, their total residual content shall not exceed
0.60%.
(l)
0.35% Cu (max), 0.03% V (max), 0.015% S (max), 0.020% P (max).
(m)
0.15-0.25% V.
(n)
The specified residuals of copper, nickel, chromium, and molybdenum (plus tungsten), shall not exceed a total content of 1.00%.
(o)
Includes the residual content of tungsten.
(p)
0.50% Cu (max), 0.10% W (max), 0.03% V (max), 0.045% S (max), 0.04% P (max).
(q)
Material class 7A is a proprietary steel and has a maximum thickness of 63.5 mm (2
1
2
in.).
(r)

Specified elements include 0.15-0.50% Cu, 0.03-0.10% V, and 0.002-0.006% B.
(s)
When residual maximums are specified for copper, nickel, chromium, tungsten, molybdenum, and vanadium, their total content shall not
exceed 0.50%.
(t)
When residual maximums are specified for copper, nickel, chromium, tungsten, and vanadium, their total content shall not exceed 0.75%.
(u)
Low-carbon grade with double austenitization.
(v)
For each reduction of 0.01% C below the maximum, an increase of 0.04% Mn is permitted up to a maximum of 2.30%.
(w)
0.20% Cu (max), 0.10% W (max), 0.02% V (max), 0.02% S (max), 0.02% P (max)

In the low-strength ranges, some specifications limit carbon and manganese content, usually to ensure satisfactory
weldability. In SAE J435c, carbon and manganese are specified to ensure that the minimum desired hardness and strength
are obtained after heat treatment. For special applications, other elements may be specified either as maximum or
minimum, depending on the characteristics desired.
The ASTM specifications that include carbon and low-alloy grades of steel castings are A 216, A 217, A 352, A 356, A
389, A 487, and A 757. The ASTM specifications with grades of carbon steel castings are listed in Table 1. Table 2 lists
the requirements for the low-alloy classes of steel castings given in some of the ASTM specifications mentioned above. In
addition, ASTM specifications may address common requirements of all steel castings for a particular type of application.
For example, ASTM A 703 specifies the general requirements of steel castings for pressure-containing parts.
If only mechanical properties are specified, the chemical composition of castings for general engineering applications is
usually left to the discretion of the casting supplier. For specific applications, however, certain chemical composition
limits have been established to ensure the development of specified mechanical properties after proper heat treatment, as
well as to facilitate welding, uniform response to heat treatment, or other requirements. Hardness is specified for most
grades of SAE J435c to ensure machinability, ease of inspection for high production rate items, or certain characteristics
pertaining to wear.
SAE J435c includes three grades, HA, HB, and HC, with specified hardenability requirements. Figure 2 plots
hardenability requirements, both minimum and maximum, for these steels. Hardenability is determined by the end-quench

hardenability test described in the article "Hardenability of Carbon and Low-Alloy Steels" in this Volume. Other
specifications require minimum hardness at one or two locations on the end-quench specimen. In general, hardenability is
specified to ensure a predetermined degree of transformation from austenite to martensite during quenching, in the
thickness required. This is important in critical parts requiring toughness and optimum resistance to fatigue.

Fig. 2 End-
quench hardenability limits for the hardenability grades of cast steel specified in SAE J435c. The
nominal carbon content of these steels is 0.30% C (see Table 1
). Manganese and other alloying elements are
added as required to produce castings that meet these limits.
Among the most commonly selected grades of steel castings are, first, a medium-carbon steel corresponding to ASTM A
27 65-35 or SAE 0030 and second, a higher-strength steel, often alloyed and fully heat treated, similar to ASTM A 148
105-85 or SAE 0105.
Particularly when the purchaser heat treats a part after other processing, a casting will be ordered to compositional limits
closely equivalent to the AISI-SAE wrought steel compositions, with somewhat higher silicon permitted. As in other steel
castings, it is best not to specify a range of silicon, but to permit the foundry to utilize the silicon and manganese
combination needed to achieve required soundness in the shape being cast. The silicon content is frequently higher in cast
steels than for the same nominal composition in wrought steel. Silicon above 0.80% is considered an alloy addition
because it contributes significantly to resistance to tempering.
Railroad equipment manufacturers and other major users of steel castings may prefer their own or industry association
specifications. Users of steel castings for extremely critical applications, such as aircraft, may use their own, industry
association, or special-purpose military specifications. Foundries frequently make nonstandard grades for special
applications or have their own specification system to meet the needs of the purchaser. Savings may be realized by using
a grade that is standard with a foundry, especially for small quantities.
Low-Carbon Cast Steels
Low-carbon cast steels are those with a carbon content of less than 0.20%. Most of the tonnage produced in the low-
carbon classification contains between 0.16 and 0.19% C, with 0.50 to 0.80% Mn, 0.05% P (max), 0.06% S (max), and
0.35 to 0.70% Si. In order to obtain high magnetic properties in electrical equipment, the manganese content is usually
held between 0.10 and 0.20%. The properties of these dynamo steels may be slightly below those of typical low-carbon
cast steels because of their manganese content.

Figure 1 includes the mechanical properties of carbon cast steels with low-carbon contents within the range of about 0.10
to 0.20%. There is very little difference between the properties of the low-carbon steels resulting from the use of
normalizing heat treatments, and the properties of those that are fully annealed. In cast steels, as in rolled steels of this
composition, increasing the carbon content increases strength and decreases ductility. Although the mechanical properties
of low-carbon cast steels are nearly the same in the as-cast condition as they are after annealing, low-carbon steel castings
are often annealed or normalized to relieve stresses and refine the structure.
Low-carbon steel castings are made in two important classes. One may be termed railroad castings, and the other
miscellaneous jobbing castings. The railroad castings consist mainly of comparatively symmetrical and well-designed
castings for which adverse stress conditions have been carefully studied and avoided.
Miscellaneous jobbing castings present a wide variation in design and frequently involve the joining of light and heavy
sections. Varying sections make it more difficult to avoid high residual stress in the as-cast shape. Because residual
stresses of large magnitude cannot be tolerated in many service applications, stress relieving becomes necessary.
Therefore, the annealing of those castings is decidedly beneficial even though it may cause little improvement of
mechanical properties. Castings for electrical or magnetic equipment are usually fully annealed because this improves the
electrical and magnetic properties.
An increase in mechanical properties can be obtained by quenching and tempering, provided the design of the casting is
such that it can be liquid quenched without cracking. Impact resistance is improved by quenching and tempering,
especially if a high tempering temperature is employed.
Uses. As has been mentioned, important castings for the railroads are produced from low-carbon cast steels. Some
castings for the automotive industry are produced from this class of steel, as are annealing boxes, annealing bottoms, and
hot-metal ladles. Low-carbon steel castings are also produced for case carburizing, by which process the castings are
given a hard, wear-resistant exterior while retaining a tough, ductile core. The magnetic properties of this class of steel
make it useful in the manufacture of electrical equipment. Free-machining cast steels containing 0.08 to 0.30% sulfur are
also produced in low-carbon grades.
Medium-Carbon Cast Steels
The medium-carbon grades of cast steel contain 0.20 to 0.50% C and represent the bulk of steel casting production. In
addition to carbon, they contain 0.50 to 1.50% Mn, 0.05% P (max), 0.06% S (max), and 0.35 to 0.80% Si. The
mechanical properties at room temperature of cast steels containing from 0.20 to 0.50% C are included in Fig. 1. Steels in
this carbon range are always heat treated, which relieves casting strains, refines the as-cast structure, and improves the
ductility of the steel.

Unlike low-carbon castings, when medium-carbon steel castings are fully annealed, it is possible to increase the yield
strength, the reduction of area, and the elongation over the entire range, compared to as-cast properties (Fig. 14). This
increase is pronounced for steel with a carbon content between 0.25 and 0.50%. The hardness and tensile strength can be
expected to fall off slightly following full annealing.

Fig. 14 Effect of annealing on the mechanical properties of medium-carbon steel castings

A very large proportion of steel castings of this grade are given a normalizing treatment, following by a tempering
treatment. The improvement in mechanical properties of medium-carbon cast steel that may be expected after normalizing
or normalizing and tempering is shown in Fig. 1.
If the design of a casting is suitable for liquid quenching, further improvements are possible in the mechanical properties.
In fact, to develop mechanical properties to the fullest degree, steel castings should be heat treated by liquid quenching
and tempering. Commercial procedure calls for tempering to obtain the desired strength level. Tempering temperatures of
650 to 705 °C (1200 to 1300 °F) are usually used to obtain higher ductility and impact properties.
High-Carbon Cast Steels
Cast steels containing more than 0.50% C are classified as high-carbon steels. This grade also contains 0.50 to 1.50% Mn,
0.05% P (max), 0.05% S (max), and 0.35 to 0.70% Si. The mechanical properties of high-carbon steels at room
temperature are shown in Fig. 1. High-carbon cast steels are often fully annealed. Occasionally, a normalizing and
tempering treatment is given, and for certain applications an oil quenching and tempering treatment may be used.
The microstructure of high-carbon steel is controlled by the heat treatment. Carbon also has a marked influence, for
example, giving 100% pearlitic structure at eutectoid composition (~0.83% carbon). Higher proportions of carbon than
eutectoid composition will increase the proeutectoid cementite, which is detrimental to the casting if it forms a network at
the grain boundaries because of improper heat treatment (for example, slow cooling from above the A
cm
temperature).
Faster cooling will prevent the formation of this network and, hence, improve the properties.
Low-Alloy Cast Steels
Low-alloy cast steels contain a total alloy content of less than 8%. These steels have been developed and used extensively
for meeting special requirements that cannot be met by ordinary plain carbon steels with low hardenability. The addition
of alloys to plain carbon steel castings may be made for any of several reasons, such as to provide higher hardenability,

increased wear resistance, higher impact resistance at increased strength, good machinability even at higher hardness,
higher strength at elevated and low temperatures, and better resistance to corrosion and oxidation than the plain carbon
steel castings. These materials are produced to meet tensile strength requirements of 485 to 1380 MPa (70 to 200 ksi),
together with some of the above special requirements.
Alloy cast steels are used in machine tools; high-speed transportation units; steam turbines; valves and fittings; railway,
automotive, excavating, and chemical processing equipment; pulp and paper machinery; refinery equipment; rayon
machinery; and various types of marine equipment. They are also used in the aeronautics field.
Low-alloy cast steels may be divided into two classes according to use: those used for structural parts of increased
strength, hardenability, and toughness, and those resistant to wear, abrasion, or corrosive attack under low- or high-
temperature service conditions. There can be no sharp distinction between the two classes because many steels serve in
both fields.
The present trend toward decreasing weight through the use of high-strength materials in lighter sections has had a
marked effect on the development of low-alloy cast steels. Low-alloys grades, such as those in the 86xx, 41xx, and 43xx
families, are capable of producing mechanical properties with a yield strength 50% higher and a tensile strength 40%
higher than carbon steels, with a ductility and impact resistance at least equal to unalloyed steels. Some 75 to 100
combinations of the available alloying materials have been regularly or occasionally used. It is doubtful that this many
variations in composition are necessary or economical.
Alloying Elements. The compositions of low-alloy cast steels are primarily characterized by carbon contents under
0.45% and by small amounts of alloying elements, which are added to produce certain specific properties. Low-alloy
steels are applied when strength requirements are higher than those obtainable with carbon steels. Low-alloy steels also
have better toughness and hardenability than do carbon steels.
Carbon-Manganese Cast Steels. Manganese is the cheapest of the alloying elements and has an important effect in
increasing the hardenability of steel. For this reason, many of the low-alloy cast steels now contain between 1 and 2%
manganese. In the normalized steels in which grain refinement is also needed, vanadium, titanium, or aluminum is often
added.
Carbon-manganese steels containing 1.00 to 1.75% Mn and 0.20 to 0.50% C have received considerable attention from
engineers in the past because of the excellent properties that can be developed with a single, relatively inexpensive
alloying element and by a single normalizing or normalizing and tempering heat treatment. Carbon-manganese steels are
also referred to as medium-manganese steels and are represented by the cast 1300 series of steels (1.60 to 1.90% Mn).
Manganese-molybdenum cast steels are very similar to the medium-manganese steels with the added

characteristics of high yield strength at elevated temperatures, higher ratio of yield strength to tensile strength at room
temperature, greater freedom from temper embrittlement, and greater hardenability. Therefore, these steels have replaced
medium-manganese steel for certain applications.
There are two general grades of manganese-molybdenum cast steels:
• 8000 series (1.0 to 1.35% Mn, 0.10 to 0.30% Mo)
• 8400 series (1.35 to 1.75% Mn, 0.25 to 0.55% Mo)
For both of these alloy types, the selected carbon content is frequently between 0.20 and 0.35%, depending on the heat
treatment employed and the strength characteristics desired.
Manganese-Nickel-Chromium-Molybdenum Cast Steels. The cast 9500 series low-alloy steels are primarily
produced for their high hardenability. Sections exceeding 125 mm (5 in.) in thickness can be quenched and tempered to
obtain a fully tempered martensitic structure. The composition range employed for the 9500 series is:
Nickel or molybdenum with manganese refines the grain structure to a lesser extent
than does vanadium, titanium, or aluminum, but each is important for increasing the
ability of the steel to air harden. Chromium and vanadium impart considerable
hardenability. Vanadium-containing steels are sometimes precipitation hardening and,
therefore, may have higher tensile and yield strengths.
Nickel Cast Steels. Among the oldest alloy cast steels are those containing nickel.
Nickel and nickel-vanadium steels are used for parts exposed to subzero conditions
(such as return headers, valves, and pump castings in oil-refinery dewaxing processes)
because of good notch toughness at lower temperatures. These steels are characterized
by high tensile strength and elastic limit, good ductility, and excellent resistance to
impact. The cast steels of the 2300 series contain 2.0 to 4.0% Ni, depending on the
grade required.
Nickel-vanadium and nickel-manganese cast steels are used for structural
purposes requiring wear resistance and high strength. The manganese-molybdenum cast
steels are also used in these applications.
Nickel-Chromium-Molybdenum Cast Steels. The addition of molybdenum to nickel-chromium steel significantly
improves hardenability and makes the steel relatively immune to temper embrittlement. Nickel-chromium-molybdenum
cast steel is particularly well suited to the production of large castings because of its deep-hardening properties. In
addition, the ability of these steels to retain strength at elevated temperatures extends their usefulness in many industrial

applications.
Chromium-Molybdenum Cast Steels. Chromium contents of about 1.00% or more provide a nominal improvement
in elevated-temperature properties. Cast steels containing chromium, molybdenum, vanadium and tungsten have given
good service in valves, fittings, turbines, and oil refinery parts, all of which are subjected to steam temperatures up to 650
°C (1200 °F).

Element
Composition, %

Manganese
1.30-1.60
Nickel
0.40-0.70
Chromium
0.55-0.75
Molybdenum

0.30-0.40

The chromium cast steels (5100 series, 0.70 to 1.10% Cr) are not in common use in the steel casting industry. Although
chromium leads the field as an alloying element for wear-resistant steels, it is seldom used alone. For example, the
chromium-molybdenum steels are widely used.
Copper-Bearing Cast Steels. There are several types of copper-containing steels. Selection among these various
types is primarily based on either their atmospheric-corrosion resistance (weathering steels) or the age-hardening
characteristics that copper adds to steel.
High-strength cast steels cover the tensile strength range of 1200 to 2070 MPa (175 to 300 ksi). Cast steels with
these strength levels and with considerable toughness and weldability were originally developed for ordnance
applications. These cast steels can be produced from any of the above medium-alloy compositions by heat treating with
liquid-quenching techniques and low tempering temperatures. Cast 4300 series steels or modifications thereof are usually
employed.

Mechanical Properties. Figure 4 shows typical room-temperature mechanical properties of low-alloy steels plotted
against yield strength. These properties are, of course, a function of alloy content, heat treatment, and section size.
Figure 15 shows the wide range of properties obtainable through changes in carbon and alloy content and heat treatment
(note the properties for 0.30% C, 1.50% Mn, and 0.35% Mo steel). Figure 16 shows the variations in mechanical
properties of a water-quenched cast 8630 steel as a function of tempering temperature. Section size effects were discussed
in the section "Mechanical Properties" of this article.

Fig. 15 Distribution of mechanical properties and carbon and alloy contents for alloy steel castings. (a) Cr-Mo-
V
steel, 1.00Cr-1.00Mo-0.25V, normalized and tempered; 25 heats. (b) Cr-Mo steel, 1.00Cr-
1.00Mo, normalized
and tempered; 25 heats. (c) Nickel steel, 0.20C-2.25Ni, normalized and tempered; 200 heats. (d) Mn-
Mo steel,
0.30C-1.50Mn-0.35Mo, normalized and tempered; 40 heats. (e) Mn-Mo steel, 0.30C-1.50Mn-
0.35Mo, quenched
and tempered; 268 to 302 HB; 50 heats. (f) Mn-Mo steel, 0.30C-1.50Mn-
0.35Mo, quenched and tempered; 300
to 321 HB; 50 heats
Physical Properties
The physical properties of cast steel are generally similar
to those of wrought steel.
Elastic constants of carbon and low-alloy cast steels
as determined at room temperature are only slightly
affected by changes in composition and structure. The
modulus of elasticity, E, is about 200 GPa (30 × 10
6
psi),
Poisson's ratio is 0.3, and the modulus of rigidity is 77.2
GPa (11.2 × 10
6

psi). Increasing temperature has a
marked effect on the modulus of elasticity and the
modulus of rigidity. A typical value of the modulus of
elasticity at 200 °C (400 °F) is about 193 GPa (28 × 10
6

psi); at 360 °C (680 °F), 179 GPa (26 × 10
6
psi); at 445
°C (830 °F), 165 GPa (24 × 10
6
psi); and at 490 °C (910
°F), 152 GPa (22 × 10
6
psi). Above 480 °C (900 °F), the
value of the modulus of elasticity decreases rapidly.
Density of cast steel is sensitive to changes in
composition, structure, and temperature. The density of
medium-carbon cast steel is about 7.8 Mg/m
3
(490
lb/ft
3
). The density of cast steel is also affected
somewhat by mass or size of section (Fig. 13d).
Electrical properties of carbon and low-alloy steel castings do not significantly affect usage. The only electrical
property that may be regarded as having any importance is resistivity, which, for various annealed carbon steel castings
with 0.07 to 0.20% C, is 0.13 to 0.14 μΩ· m. Resistivity increases with carbon content and is about 0.20 μΩ· m at 1.0% C.
Magnetic Properties. Steel castings from the housings for electrical machinery and magnetic equipment and carry
only stray fluxes around the machines; hence, the magnetic properties of steel castings are less important than they were

formerly when core material was manufactured from commercial cast iron and steel. Low-carbon cast dynamo steel has
supplanted other cast metals for housings and frames for magnetic circuits.
The carbon content of the steel is very important in determining the magnetic properties. The maximum permeability and
the saturation magnetization decrease, and the coercive force increases, as the carbon content increases. Manganese,
phosphorus, sulfur, and silicon also increase the magnetic hysteresis loss in cast steels. This loss is equal to about 10 J/m
3

per cycle for B = 1 T for each 0.10% Mn, 0.01% S, and 0.01% P. Other factors being equal, the magnetic hysteresis loss
is unaffected by more than 0.02% P. Magnetic properties change considerably, depending on the mechanical treatment
and heat treatment of the steel.
Cast dynamo steels contain about 0.10% C, with other alloying elements held to a minimum; the castings are furnished in
the annealed condition. Specifications require 0.05 to 0.15% C, 0.20% Mn, and 0.35 to 0.60 or 1.50 to 2.00% Si.
The magnetic properties of annealed cast dynamo steel that may normally be expected are:

Property

Maximum permeability, mH/m

18.6

Hysteresis loss (induction for H

1.91


Fig. 16 Mechanical properties of water-
quenched cast
8630 steel
= 11.9 kA/m), T
Saturation magnetization, T

2.14

Residual induction, T
1.10

Coercive force, A/m 29

As the carbon content is increased, maximum permeability and saturation magnetization decrease, and coercive force
increases. Also, an increase in manganese and sulfur content increase the magnetic hysteresis loss.
Silicon and aluminum eliminate the allotropic transformation in iron and permit annealing at high temperature without
recrystallization during cooling; thus, large grains can be obtained. These elements can be added in large quantities
without affecting magnetic properties, but they do reduce the saturation value and increase the brittleness of the metal.
Hysteresis loss varies directly with grain size number; therefore, the larger the grain size, the better the properties.
Residual alloy content should be low because it lowers saturation value.
The factors that improve the machinability of dynamo steel decrease the magnetic properties. A disadvantage in the use of
pure iron for dynamo steel is low resistivity. The iron must be rolled thin to keep eddy currents down; otherwise, the
magnetic properties will be poor.
Volumetric Changes. In the foundry, all volume changes of a metal are pertinent, whether they occur in the liquid
state, during solidification, or in the solid state. Of particular interest is the contraction that results when molten steel
solidifies.
Volume changes that occur in the liquid state as the cast metal cools affect the planning for adequate metal to fill the
mold. Contraction is of the order of 0.9% per 100 °C (180 °F) for a 0.30% C steel. The exact amount of contraction will
vary with the chemical composition, but it is usually within the range of 0.8 to 1.0% per 100 °C (180 °F) for carbon and
low-alloy steels. A larger contraction occurs upon solidification (2.2% for nearly pure iron to 4% for a 1.00% C steel).
For cast carbon and low-alloy steels, a solidification contraction of 3.0% is generally assumed.
The greatest amount of contraction occurs as the solidified metal cools to room temperature. Solid-state contraction from
the solidus to room temperature varies between 6.9 and 7.4% as a function of carbon content. Alloying elements have no
significant effect on the amount of this contraction. The rigid form of the mold hinders contraction and results in the
formation of stresses within the cooling casting that may be great enough to cause fracture or hot tears in the casting. The
hot metal has low strength just after solidification. The rigidity of the mold makes the proper relation of casting

configuration to accommodate this contraction one of the most important factors in producing a successful casting.
In commercial production, a combination of all three contraction components may operate simultaneously. Molten metal
in contact with the mold wall solidifies quickly and proceeds to solidify toward the center of the casting. The solid
envelope undergoes contraction in the solid state, while a portion of the still-molten metal is solidifying. The remaining
molten metal contracts as its temperature decreases toward the freezing point. Because of contraction factors, many
casting designs require considerable development to produce a sound casting.
Engineering Properties
Wear Resistance. Cast steels have wear resistance comparable to that of wrought steel of similar composition and
condition. Chromium leads the field as an alloying element for wear-resistant steels but is seldom used alone. Nickel-
vanadium, manganese-molybdenum, and nickel-manganese cast steels are used for numerous structural purposes
requiring wear resistance and high strength.
Corrosion resistance of cast steel is similar to that of wrought steel of equivalent composition. Data published on the
corrosion resistance of wrought carbon and low-alloy steels under various conditions may be applied to cast steels.
Low-alloy steels are generally not considered corrosion resistant, and casting compositions are not normally selected on
the basis of corrosion resistance. In some environments, however, significant differences are observed in corrosion
behavior such that the corrosion rate of one steel may be half that of another grade. In general, steels alloyed with small
amounts of copper tend to have somewhat lower corrosion rates than copper-free alloys. As little as 0.05% Cu has been
shown to exert a significant effect. In some environments, nominal levels of nickel, chromium, phosphorus, and silicon
may also bring about modest improvements, but when these four elements are present, the addition of copper holds little
if any advantage. Detailed information on the corrosion resistance of steels is available in the articles "Corrosion of
Carbon Steels," "Corrosion of Alloy Steels," and "Corrosion of Cast Steels" in Corrosion, Volume 13 of ASM Handbook,
formerly 9th Edition Metals Handbook.
Soil Corrosion. Cast steel pipe has been tested for various periods up to 14 years in different types of soil. The results
of these tests were compared directly with results from tests on wrought steel pipe of similar composition, and no
significant difference in the corrosion of the two materials could be detected. However, the actual corrosion rate and rate
of pitting of the cast pipe varied widely, depending on the soil and aeration conditions.
Elevated-Temperature Properties. Steels operating at temperatures above ambient are subject to failure by a
number of mechanisms other than mechanical stress or impact. These include oxidation, hydrogen damage, sulfide
scaling, and carbide instability, which manifests itself as graphitization.
The environmental factors involved in elevated-temperature service (370 to 650 °C, or 700 to 1200 °F) require that steels

used in this temperature range be carefully characterized. As a consequence, four ASTM specifications have been
developed for cast carbon and low-alloy steels for elevated-temperature service. One of these specifications, ASTM A
216, describes carbon steels; the other three, A 217, A 356, and A 389, cover low-alloy steels.
The two alloying elements common to nearly all the steel compositions used at elevated temperatures are molybdenum
and chromium. Molybdenum contributes greatly to creep resistance. Depending on microstructure, it has been shown that
0.5% Mo reduces the creep rate of steels by a factor of at least 10
3
at 600 °C (1110 °F).
Chromium also reduces the creep rate, although modestly, at levels to approximately 2.25%. At higher chromium levels,
creep resistance is somewhat reduced. Vanadium improves creep strength and is indicated in some specifications. Other
elements that improve creep resistance include tungsten, titanium, and niobium. The effect of tungsten is similar to that of
molybdenum, but on a weight percent basis more tungsten is required in order to be equally beneficial. Titanium and
niobium have been shown to improve the creep properties of carbon-free alloys, but because they remove carbon from
solid solution, their effect tends to be variable. None of the latter three elements appears in U.S. specifications for cast
steels for elevated-temperature service.
Low-Temperature Toughness. In addition to the soundness, strength, and microstructure of a metal, toughness, too,
is strongly affected by temperature. Steel castings suitable for low-temperature service are specified in ASTM A 352 and
A 757. Figure 17 shows the effect of temperature on the impact resistance of three grades of cast steels conforming to
ASTM A 352. Figure 17(b) also shows the effect of heat treatment on the impact resistance of grade LC2-1.

Fig. 17 Effect of temperature on the Charpy V-notch energy of a carbon steel and two low-alloy c
ast steels
specified in ASTM A 352 for low-temperature service. (a) Charpy V-
notch energies for a carbon cast steel,
0.30% C (max) with 1.00% Mn (max), quenched, tempered, and stress relieved, taken from a 50 × 230 × 210
mm (2 × 9 × 8
1
4
in.) test block and from a 75 × 230 × 283 mm (3 × 9 × 11
1

8
in.) test block. (b) Charpy V-
notch energies for nickel-chromium-
molybdenum cast steel specimens (taken from 50 × 230 × 210 mm, or 2 ×
9 × 8
1
4
in., test block) from steel with two different tempering and aging treatments after being air cooled
from 955 °C (1750 °F), reheated to 900 °C (1650 °F), and then water quenched. (c) Charpy V-
notch energies
for 2
1
2
% Ni cast steel specimens (taken from 75 × 230 × 283 mm, or 3 × 9 × 11
1
8
in., test block) after being
air cooled (normalized, N) from 900 °C (1650 °F) and either tempered (T) at 620 °C (1150 °F) or reheated to
900 °C (1650 °F), water quenched (Q) a
nd then tempered at 620 °C (1150 °F). All specimens were taken at
locations greater than one-
fourth the thickness in from the surface of test blocks having an ASTM grain size of 6
to 8. The curves represent average values for several tests at each test temperature.
Fracture Toughness. Figure 18 shows the effect of temperature on the fracture toughness of a carbon (0.25% C, max)
cast steel specified in ASTM A 216. Table 7 shows the effect of lower temperatures on the fracture toughness of five cast
steels. As described below, the fracture toughness values in Table 7 are reported in terms of either J
Ic
or J
c
when

circumstances prevented the direct determination of K
Ic
.

Fig. 18 Temperature dependence of plane-strain fracture toug
hness of a carbon steel casting (grade WCC of
ASTM A 216). Test blocks were 508 × 508 × 1219 mm (20 × 20 × 48 in.), annealed 8 h at 900 °C (1650 °F),
furnace cooled to 315 °C (600 °F), tempered 8 h at 605 °C (1125 °F), furnace cooled to 315 °C (600 °F),
re
heated to 955 °C (1750 °F) and held 8 h, furnace cooled to 900 °C (1650 °F), equalized, accelerated cooled
to 95 °C (200 °F), final tempered 8 h at 650 °C (1200 °F), and air cooled. Compact tension specimens of three
thicknesses as indicated were used. The
open data points are the only symbols that indicate valid test results.
Source: Ref 4
Table 7 Fracture toughness values for five cast steels at room temperature and -45 °C (-50 °F)
Steel
Room temperature
J
Ic
J
c
K
Ic

K
c


kJ/m
2

in. · lbf/in
2


kJ/m
2


in. · lbf/in
2


MPa
m
ksi
in
MPa
m
ksi
in

0030 73 415 . . . . . . 130 118 . . .
. . .
. . . . . . 37
(a)
209 . . . . . . 92
(a)

84
0050A
. . . . . . 25
(b)
145 . . . . . . 77
(b)

70
C-Mn 84 479 . . . . . . 138 126 . . .
. . .
Mn-Mo

139 794 . . . . . . 179 163 . . .
. . .
8630 80 456 . . . . . . 135 123 . . . . . .
-45 °C (-50 °F)
J
Ic
J
c
K
Ic
K
c

Steel
kJ/m
2

in. · lbf/in
2


kJ/m
2


in. · lbf/in
2


MPa
m
ksi
in
MPa
m
ksi
in

Percent decrease

. . . . . . 49
(a)
282 . . . . . . 108
(a)
98
32
0030

. . . . . . . . . . . . 93
(b)
85
40
. . . . . . 17
(a)
95 . . . . . . 61
(a)
56
55
0050A
14
(b)
78 . . . . . . 56
(b)
51
46
C-Mn 75 428 . . . . . . 132 120 . . . . . .
11
Mn-Mo

118 674 . . . . . . 166 151 . . . . . .
15
. . . . . . 38
(a)
218 . . . . . . 94
(a)
86
52
8630

. . . . . . 30
(b)
174 . . . . . . 85
(b)
77 62
Source: Ref 3
(a)

Average value.
(b)

Lowest value.

For cost-effective testing, the J-integral approach was used to estimate the fracture toughness of some of the steels in
Table 7. The J-integral approach can be used to estimate the fracture toughness of steels having considerable elastic-
plastic behavior (Ref 5) without using large specimens. Four of the steels exhibited appreciable ductility and low yield
strength in smooth-specimen tensile tests, which could require that specimen thickness and crack length range from about
50 to 500 mm (2 to 20 in.) for valid K
Ic
determinations. The larger dimensions are unreasonable for cost-effective testing.
Therefore, the J-integral used to estimate fracture toughness characteristics without the use of large specimens. For linear
elastic plane strain, J
Ic
is related to K
Ic
for linear elastic plane strain:
2
(1²)
IC
ICIC

K
JGv
E
==−


(Eq 3)
where G is the strain energy release rate per unit crack extension, E is Young's modulus, and ν is Poisson's ratio.
Valid values of J
Ic
, and hence conservative estimates of K
Ic
, were obtained for four of the cast steels at room temperature
and two cast steels at -45 °C (-50 °F) (Table 7). Only J
c
, and hence estimates of K
c
, were obtained for the other material
and temperature conditions. The tests that did not produce valid J
Ic
value were in the Charpy V-notch transition
temperature energy region. Landes et al., using A 471 wrought steel, showed that J
c
fracture toughness values obtained in
this region from small J-integral specimens had substantial scatter and that the lower limit of this J
c
scatter band was
similar to that of equivalent toughness measured on larger specimens (Ref 6). Landes et al. suggested that the lower
boundary value of the J
c

scatter may be reasonable to use for conservative-design criteria in the Charpy V-notch transition
temperature region.
As shown in Table 7, Mn-Mo cast steel exhibited the highest fracture toughness (J
Ic
or K
Ic
) at both room temperature and
-45 °C (-50 °F), while the 0050A cast steel showed the lowest fracture toughness (J
c
or K
c
) at both temperatures. The
three martensitic cast steels (C-Mn, Mn-Mo, and 8630) had better fracture toughness at room temperature than the two
ferritic-pearlitic cast steels (0030 and 0050A). The 8630 cast steel had the largest decrease in fracture toughness at -45 °C
(-50 °F) compared to room temperature. The C-Mn and Mn-Mo steels had ductile stable crack growth and the highest J
values at both room temperature and -45 °C (-50 °F). Based on J-integral tests, they were the best steels at both
temperatures.
Machinability. Extensive lathe and drilling tests on steel castings have not revealed significant differences in the
machinability of steels made by different melting processes, nor of wrought and cast steel, provided strength, hardness,
and microstructure are equivalent. The skin or surface on a sand mold casting often wears down cutting tools rapidly,
possibly because of adherence of abrasive mold materials to the casting. Therefore, the initial cut should be deep enough
to penetrate below the skin, or the cutting speed may be reduced to 50% of that recommended for the base metal.
Microstructure has considerable effect on the machinability of cast steels. It is sometimes possible to improve the
machining characteristics of a steel castings by 100% through normalizing, normalizing and tempering, or annealing.
Weldability. Steel castings have welding characteristics comparable to those of wrought steel of the same composition,
and welding these castings involves the same considerations.
The severe quenching effect produced when using a small welding rod to weld a large section results in the formation of
martensite in the base metal area immediately adjacent to the weld (in the heat-affected zone). This can happen even in
low-carbon steel, causing loss of ductility in the heat-affected zone. Usually cast steels with a maximum of 0.20% C and
0.50% Mn present fewer problems from this effect. However, it is essential that all of the carbon steels (with more than

0.20% C) and the air-hardening alloyed steels be preheated before welding at the standard recommended temperatures,
maintaining a proper interpass temperature, and then postweld heat treated to produce sufficient ductility.
To prevent cracking in carbon and low-alloy cast steels, the hardness of the weld bead should not exceed 350 HV, except
where conditions are such that only compressive forces result from the welding. This value may not be low enough in
configurations in which extreme restraint is involved.
Virtually all castings receive a stress-relief heat treatment after welding, even composite fabrications in which steel
castings are welded to wrought steel shapes.
The maximum compositional limits that have been placed by the industry on readily weldable grades of castings are
0.35% C, 0.70% Mn, 0.30% Cr, and 0.25% Mo (max) plus W, with a total of 1.00% undesirable elements, predicated on
the widespread use of stress-relief heat treatment in the steel casting industry. For each 0.01% decrease in the specified
maximum carbon content, most specifications permit an increase of 0.04% Mn above the maximum specified, up to a
maximum of 1.00% (ASTM A 27, grade 70-40, and A 216, grade WCC, allow up to a maximum of 1.40% Mn).
Specifications for weldable grades of cast steel are ASTM A 27, A 216, A 217, A 352, A 487, and A 757. Specifications
covering control of weld quality are ASTM E 164 and E 390.
Many welds that fail do not fail in the weld but in the zone immediately adjacent to the weld. While the weld is being
made, this zone is heated momentarily to a melting temperature. The temperature decreases as the distance from the weld
increases. Such heating induces structural changes, specifically the development of hard, brittle areas adjacent to the weld
deposits, which reduce the toughness of the area and frequently cause cracking during and after cooling. Likewise, certain
alloying elements other than carbon, such as nickel, molybdenum, and chromium, bring about air hardening of the base
metal. For these reasons, the quantity of alloying elements to be used must be limited unless special precautions are taken,
such as the preheating of the base metal to 150 to 315 °C (300 to 600 °F). Increased hardness in the heat-affected zone of
the base metal can be removed by postweld heat treating the welded casting or by heating it for definite periods at 650 to
675 °C (1200 to 1250 °F). This also relieves stresses from welding.
For the arc welding of steel castings, a high-grade heavily coated electrode (AWS E7018 type), granular flux, or CO
2

atmosphere is generally desirable. These coatings contain little or no combustible material. Mineral coatings are often
used to keep hydrogen absorption at a minimum and thereby limit underbead cracking. Selection of the number of passes
and of welding conditions is similar to welding practice for wrought steels.
Welds in castings may be radiographed by gamma- or x-ray methods to ascertain the degree of homogeneity of the

welded section. The most common imperfections are incomplete fusion, slag inclusions, and gas bubbles. Magnetic
particle inspection is also useful in the detection of surface and near-surface cracks.
The mechanical properties of welds joining cast steel to cast steel and of welds joining cast steel to wrought steel are of
the same order as similar welds joining wrought steel to wrought steel. Most tensile specimens machined across the weld
break outside the weld, in the heat-affected zone. This does not mean that the weld is stronger than the casting base metal.
Closely controlled welding techniques and stress relieving are necessary to prevent brittleness in the heat-affected zone.

References cited in this section
3.

"Fatigue and Fracture Toughness of Five Carbon or Low-
Alloy Steels at Room or Low Climatic
Temperatures," Research Report 9A, Steel Founders' Society of America, Oct 1982
4.

H.D.
Greenberg and W.G. Clark, Jr., A Fracture Mechanics Approach to the Development of Realistic
Acceptance Standards for Heavy Walled Steel Castings, Met. Eng. Q., Vol 9 (No. 3), Aug 1969, p 30-39
5.

J.R. Rice, A Path Independent Integral and the Approximate
Analysis of Strain Concentration by Notches
and Cracks, J. Appl. Mech., Vol 35, June 1968, p 379
6.

J.D. Landes and D.H. Shaffer, Statistical Characteristics of Fracture in the Transition Region, in
Fracture
Mechanics, STP 700, American Society for Testing and Materials, 1980, p 368
Nondestructive Inspection
Highly stresses steel castings for aircraft and for high-pressure or high-temperature service must pass rigid nondestructive

inspection. ASTM specifications E 186, E 280, and E446 cover radiographic standards for steel castings; E 94 covers
ASTM recommended practice for radiographic testing; and E 142 covers the quality control of radiographic testing.