Foundations of Materials Science and Engineering
6th Edition
ISBN: 9781259696558
Author: SMITH
Publisher: MCG
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Chapter 9.13, Problem 79AAP
(a)
To determine
Express the Rockwell C hardness of the 5140 steel bar at
(b)
To determine
Express the Rockwell C hardness of the 5140 steel bar at the center.
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Check out a sample textbook solutionStudents have asked these similar questions
Q1: Austenitized 40 mm diameter 5140 alloy steel bar is quenched in agitated oil. Predict what is the
Rockwell hardness of this bar will be at (a) its surface and (b) its center (c) What do you think about
the difference in hardness number between the center and surface (d) Differentiate between hardness
and hardenability (e) Rank the steels in the figure below from lowest to highest hardenability and
explain why.
Cooling rate at 700°C (°C/sec)
300
150
011/3 55
100
600
Bar diameter (mm)
80
60
40
20
0
OLL
0
0
ww
25 12.5 8
5
S
--------------
M-R
10
3/4-R
Agitated oil
15 20
1/4
3/4
Distance from quenched end. De
(Jominy distance)
5.5
4
3
Bar diameter (in.)
0
25 mm
1 in.
Hardness (Rockwell C)
Where (C = center, S = surface, M-R mid-radius)
65
60
55
50
45
40
35
30
25
20
15
10
0
10
1
20
Distance from quenched end (mm)
5140
1
30
L
2 4 6 8 10 12 14 16 18 20 22 24 26 28 30 32
Distance from quenched end (sixteenths of an inch)
4340
40
9840
4140
8640
50
Q3: With a moderately agitated water, a cylindrical piece of steel with 80 mm diameter is to be quenched. The
hardnesses of the surface and center must be at least 55 and 40 HRC, respectively. Which of these alloys will
satisfy the following requirements: 1040, 5140, 4340, 4140, 8620, 8630, 8640, and 8660?
Cooling rate at 700c
Cooling rate at 700°c
170 70 31 18
5.6
3.9 "C
270 170 70 31 18 9
60
2 "Os
5.6
3.9
2.8
100
100
50
4340
80
75
3
Surface
40
4140
Center
8640
30
5140
25
1040
20
10
20
30
40
50 mm
10
20
30 mm
Distance from quenched end
Equivalent distance from quenched end
Figure 3
Figure 4
Hardness, HRC
Percent martensite
Diameter of bar (mm)
A nitriding heat treatment of a BCC steel normally requires 2 h at 600 °C. What temperature would be required to reduce the heat treatment time to 1 h?(Q =76570 J/mol, Do =0.0047x10- 4 m2/s)
and the last one. thanks for ur helping.
Chapter 9 Solutions
Foundations of Materials Science and Engineering
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