Q13. The wear resistance of a steel gear is to be improved by hardening its surface. This is to be accomplished by increasing the carbon content within an outer surface layer as a result of carbon diffusion into the steel; the carbon is to be supplied from an external carbon-rich gaseous atmosphere at an elevated and constant temperature. The initial carbon content of the steel is 0.20 wt%, whereas the surface concentration is to be maintained at 1.00 wt%. For this treatment to be effective, a carbon content of 0.60 wt% must be established at a position 0.75 mm below the surface. Specify an appropriate heat treatment in terms of temperature and time for temperatures between 900 °C and 1050 °C (you may select any 3 temperatures). For the diffusion of carbon in steel, Do = 2.3 x 10 m²/s, Q = 148 kJ/mol. (The error function values are given below) erfl2) erfl:) erf(2) 0.55 0.5633 1.3 1.4 0.9340 0.025 0.05 0.0282 0.60 0.6039 0.9523 0.65 0.70 0.0564 0.6420 1.5 0.9661 0.10 0.1125 0.6778 1.6 0.9763 0.15 0.20 0.75 0.1680 0.2227 0.2763 0.7112 0.7421 0.7707 1.7 1.8 1.9 0.9838 0.25 0.30 0.35 0.80 0.85 0.90 0.9891 0.9928 0.9953 0.3286 0.7970 2.0 0.3794 2.2 2.4 2.6 2.8 0.95 0.8209 0.9981 0.40 0.4284 1.0 0.8427 0.9993 0.45 0.50 0.4755 0.5205 0.8802 0.9103 1.1 0.9998 1.2 0.9999
Q13. The wear resistance of a steel gear is to be improved by hardening its surface. This is to be accomplished by increasing the carbon content within an outer surface layer as a result of carbon diffusion into the steel; the carbon is to be supplied from an external carbon-rich gaseous atmosphere at an elevated and constant temperature. The initial carbon content of the steel is 0.20 wt%, whereas the surface concentration is to be maintained at 1.00 wt%. For this treatment to be effective, a carbon content of 0.60 wt% must be established at a position 0.75 mm below the surface. Specify an appropriate heat treatment in terms of temperature and time for temperatures between 900 °C and 1050 °C (you may select any 3 temperatures). For the diffusion of carbon in steel, Do = 2.3 x 10 m²/s, Q = 148 kJ/mol. (The error function values are given below) erfl2) erfl:) erf(2) 0.55 0.5633 1.3 1.4 0.9340 0.025 0.05 0.0282 0.60 0.6039 0.9523 0.65 0.70 0.0564 0.6420 1.5 0.9661 0.10 0.1125 0.6778 1.6 0.9763 0.15 0.20 0.75 0.1680 0.2227 0.2763 0.7112 0.7421 0.7707 1.7 1.8 1.9 0.9838 0.25 0.30 0.35 0.80 0.85 0.90 0.9891 0.9928 0.9953 0.3286 0.7970 2.0 0.3794 2.2 2.4 2.6 2.8 0.95 0.8209 0.9981 0.40 0.4284 1.0 0.8427 0.9993 0.45 0.50 0.4755 0.5205 0.8802 0.9103 1.1 0.9998 1.2 0.9999
Introduction to Chemical Engineering Thermodynamics
8th Edition
ISBN:9781259696527
Author:J.M. Smith Termodinamica en ingenieria quimica, Hendrick C Van Ness, Michael Abbott, Mark Swihart
Publisher:J.M. Smith Termodinamica en ingenieria quimica, Hendrick C Van Ness, Michael Abbott, Mark Swihart
Chapter1: Introduction
Section: Chapter Questions
Problem 1.1P
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Transcribed Image Text:Q13. The wear resistance of a steel gear is to be improved by hardening its surface. This is to
be accomplished by increasing the carbon content within an outer surface layer as a result of
carbon diffusion into the steel; the carbon is to be supplied from an external carbon-rich gaseous
atmosphere at an elevated and constant temperature. The initial carbon content of the steel is
0.20 wt%, whereas the surface concentration is to be maintained at 1.00 wt%. For this treatment
to be effective, a carbon content of 0.60 wt% must be established at a position 0.75 mm below
the surface.
Specify an appropriate heat treatment in terms of temperature and time for temperatures
between 900 °C and 1050 °C (you may select any 3 temperatures). For the diffusion of carbon
in steel, Do = 2.3 x 10 m/s, Q = 148 kJ/mol. (The error function values are given below)
erf(2)
erf(z)
0.55
0.60
1.3
1.4
0.5633
0.9340
0.025
0.0282
0.6039
0.9523
0.05
0.0564
0.65
0.6420
1.5
0.9661
0.10
0.1125
0.70
0.6778
1.6
0.9763
0.15
0.20
0.25
0.30
0.35
0.1680
0.2227
0.2763
0.75
0.80
0.85
0.7112
0.7421
0.7707
1.7
1.8
1.9
2.0
0.9838
0.9891
0.9928
0.3286
0.90
0.7970
0.9953
0.95
2.2
0.9981
0.9993
0.3794
0.8209
0.40
0.4284
1.0
0.8427
2.4
0.45
0.50
0.4755
0.5205
1.1
1.2
0.8802
0.9103
2.6
2.8
0.9998
0.9999
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