Steel Heat Treatment - Metallurgy and Technologies 2nd ed - G. Totten (CRC_ 2010) WW Part 7 pdf

For medium-alloy steels up to 6308C (11668F), with a cooling rate of 15–20 K/h (furnace
cooling)
For high-alloy steels up to 6008C(11128F), with a cooling rate of 10–15 K/h (furnace cooling)
Further cooling below the temperatures indicated is usually performed in air
6.2.5 RECRYSTALLIZATION ANNEALING
Recrystallization annealing is an annealing process at temperatures above the recrystalliza-
tion temperature of the cold-worked material, without phase transformation, that aims at
regeneration of properties and changes in the structure that exists after a cold-forming process
600ЊC
130
110
90
70
0 50 100 150 200
Time, h
Hardness, HRB
625ЊC
650ЊC
675ЊC
700ЊC
FIGURE 6.78 Hardness of an unalloyed steel with 0.89% C after soft annealing, depending on the
spheroidization time and temperature. (From H.J. Eckstein (Ed.), Technologie der Wa
¨
rmebehandlung
von Stahl, 2nd ed., VEB Deutscher Verlag fu
¨
r Grundstoffindustrie, Leipzig, 1987.)
a
b
200
Turning speed (v

60
), m/min
Tensile strength R
m
, N/mm
2

150
100
50
500 600 700 900800 1000
c
FIGURE 6.79 Influence of the ultimate tensile strength and degree of spheroidization on machinability
of steels for carburizing and structural steels for hardening and tempering, expressed as 1 h turning
speed (v
60
) in m/min. (a) Spheroidization degree less than 30%; (b) spheroidization degree between 40
and 60%; (c) spheroidization degree greater than 70%. (From G. Spur and T. Sto
¨
ferle (Eds.), Handbuch
der Fertigungstechnik, Vol. 4/2, Wa
¨
rmebehandeln, Carl Hanser, Munich, 1987.)
ß 2006 by Taylor & Francis Group, LLC.
For medium-alloy steels up to 6308C (11668F), with a cooling rate of 15–20 K/h (furnace
cooling)
For high-alloy steels up to 6008C(11128F), with a cooling rate of 10–15 K/h (furnace cooling)
Further cooling below the temperatures indicated is usually performed in air
6.2.5 RECRYSTALLIZATION ANNEALING
Recrystallization annealing is an annealing process at temperatures above the recrystalliza-

tion temperature of the cold-worked material, without phase transformation, that aims at
regeneration of properties and changes in the structure that exists after a cold-forming process
600ЊC
130
110
90
70
0 50 100 150 200
Time, h
Hardness, HRB
625ЊC
650ЊC
675ЊC
700ЊC
FIGURE 6.78 Hardness of an unalloyed steel with 0.89% C after soft annealing, depending on the
spheroidization time and temperature. (From H.J. Eckstein (Ed.), Technologie der Wa
¨
rmebehandlung
von Stahl, 2nd ed., VEB Deutscher Verlag fu
¨
r Grundstoffindustrie, Leipzig, 1987.)
a
b
200
Turning speed (v
60
), m/min
Tensile strength R
m
, N/mm

2

150
100
50
500 600 700 900800 1000
c
FIGURE 6.79 Influence of the ultimate tensile strength and degree of spheroidization on machinability
of steels for carburizing and structural steels for hardening and tempering, expressed as 1 h turning
speed (v
60
) in m/min. (a) Spheroidization degree less than 30%; (b) spheroidization degree between 40
and 60%; (c) spheroidization degree greater than 70%. (From G. Spur and T. Sto
¨
ferle (Eds.), Handbuch
der Fertigungstechnik, Vol. 4/2, Wa
¨
rmebehandeln, Carl Hanser, Munich, 1987.)
ß 2006 by Taylor & Francis Group, LLC.
100
0
(a)
Temperature, 8C
200
300
400
500
600
700
800

900
0.01 0.1 1
Time, s
10 100 1000
100
0
(b)
Temperature, ЊC
200
300
400
500
600
700
800
900
0.01 0.1 1
Time, s
10 100 1000
FIGURE 6.117 Comparison of measured (- - -) and calculated (—) cooling curves for the center of a
50-mm diameter bar quenched in (a) mineral oil at 208C, without agitation and (b) 25% PAG polymer
solution, 408C bath temperature, and 0.8 m/s agitation rate.
1
0
100
200
300
400
500
600

700
800
900
1000
AISI 4140
Chemical
composition
Austenitizing temp. 850 ЊC
Time, s
10
Temperature, ЊC
10
2
10
3
10
4
10
5
10
6
C
0.38 0.23 0.64 0.019 0.013 0.99 0.17 0.16 0.08 <0.01
Si Mn P S Cr Cu Mo Ni V
58
2
3
85
75
B

A
M
M
s
S
3/4 R
2
7
30
70
60
40
60
40
A
c3
A
c1
F
P
C
10
5
12
75
53
52 34 28 27 230 220
200
FIGURE 6.118 CCT diagram of AISI 4140 steel with superimposed calculated cooling curves for
surface (S), three-quarter radius (3/4R) and center (C) of a round bar of 50-mm diameter.

ß 2006 by Taylor & Francis Group, LLC.
ASTM 3
100
50
20
0
−50
−100
−150
200 400 600 800
Yield strength R
p,
N/mm
2
Transition temperature, ЊC
1000 1200 1400
RT
ASTM 7
ISO-V longitudinal
100% F + P
50% F + P/50% B
30% F/70% B
10% F/90% B
100% B
u
100% B
l
25% M/75% B
50% M/50% B
75% M/25% B

GS
GS
GS
F−P
B
M
FIGURE 6.133 Transition temperature as a function of yield strength and microstructure. F, Ferrite;
P, pearlite; B, bainite; B
u
, upper bainite; B
1
, lower bainite; M, martensite; GS, grain size (ASTM). (From
G. Spur and T. Sto
¨
ferle (Eds.), Handbuch der Fertigungstechnik, Vol. 4/2, Wa
¨
rmebehandeln, Carl Hanser,
Munich, 1987.)
M
M
(a)
(b)
(c)
25
20
15
70
50
60
40

30
20
10
0
250
200
150
100
50
0
300 500 700
Yield strength R
p
,

N/mm
2
900 1100 1300
10
5
Elongation, %
Contraction Z, %
0
B
B
F + P
F + P
M
B
F + P

Impact energy (20ЊC)
FIGURE 6.134 (a) Elongation; (b) reduction of area; and (c) impact toughness of hardened and
tempered steels having about 0.4% C, as a function of structure constituents and yield strength. F,
Ferrite; P, pearlite; B, bainite; M, martensite. Grain size: ASTM 6–7. Impact toughness: ISO notch
specimens. Testing direction: longitudinal. (From G. Spur and T. Sto
¨
ferle (Eds.), Handbuch der Ferti-
gungstechnik, Vol. 4/2, Wa
¨
rmebehandeln, Carl Hanser, Munich, 1987.)
ß 2006 by Taylor & Francis Group, LLC.