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The Science and Engineering of Materials (MindTap Course List)
7th Edition
ISBN: 9781305076761
Author: Donald R. Askeland, Wendelin J. Wright
Publisher: Cengage Learning
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Textbook Question
Chapter 5, Problem 5.31P
A 1-mm-thick BCC iron foil is used to separate a region of high nitrogen gas concentration of
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A BCC iron alloy containing 0.05 wt% C is carburized at 1050°C such that the carbon concentration is 0.5 wt% at a distance
2mm from the surface. Meanwhile, the carbon concentration at the surface is kept constant at 1.5 wt% C.
a. What is the value of the diffusion constant for carbon diffusing into BCC Fe at 1050 °C? Show all work.
Write the relevant equation for the diffusivity within this box:
Write the values of all of the parameters in the equation above within the box below:
Write your final answer for the diffusivity within this box:
b. Determine the diffusion time required to achieve the carbon profile described above. Show all work.
Write the relevant equation needed to
solve this problem within this box:
Write the values of all of the given parameters in the equation above within the box below:
Write the value for erf(z) within this box:
A mechanism for hardening steel is called carburization. To achieve this process, the piece of steel is exposed to an atmosphere rich in hydrocarbon such as methane (CH4). Consider a steel with a carbide concentration of 0.25wt%, which must be treated at 950˚C. If the carbon concentration at the surface is suddenly increased to 1.20wt%, how long does it take for a penetration of 0.5mm from the surface to reach a concentration of 0.80wt%? . The diffusion coefficient for carbon in iron at this temperature is 1.6 x 10-11 m2s-1. Assume that the piece of steel is semi-finite. Use the table below.
You wish to carburize 0.2 wt% C steel ball bearings. The balls have a
diameter of 2.5 mm. You anneal them at 930 °C in an atmosphere
which fixes the surface carbon concentration at 1 wt% C.
(a) How long will it take to raise the average C concentration to
0.6 wt% ?
(b) What is the concentration at the centre of each ball at this time?
Chapter 5 Solutions
The Science and Engineering of Materials (MindTap Course List)
Ch. 5 - What is the driving force for diffusion?Ch. 5 - Give three examples of materials processes that...Ch. 5 - In the carburization treatment of steels, what are...Ch. 5 - Prob. 5.4PCh. 5 - Prob. 5.5PCh. 5 - Prob. 5.6PCh. 5 - Prob. 5.7PCh. 5 - A certain mechanical component is heat treated...Ch. 5 - Prob. 5.9PCh. 5 - Prob. 5.10P
Ch. 5 - Prob. 5.11PCh. 5 - Prob. 5.12PCh. 5 - Prob. 5.13PCh. 5 - Prob. 5.14PCh. 5 - Prob. 5.15PCh. 5 - Prob. 5.16PCh. 5 - Compare the diffusion coefficients of carb on in...Ch. 5 - Prob. 5.18PCh. 5 - Activation energy is sometimes expressed as...Ch. 5 - Prob. 5.20PCh. 5 - The activation energy for the diffusion of copper...Ch. 5 - Prob. 5.22PCh. 5 - Prob. 5.23PCh. 5 - Prob. 5.24PCh. 5 - Prob. 5.25PCh. 5 - Write down Fick’s first law of diffusion. Clearly...Ch. 5 - Prob. 5.27PCh. 5 - Prob. 5.28PCh. 5 - Prob. 5.29PCh. 5 - Prob. 5.30PCh. 5 - A 1-mm-thick BCC iron foil is used to separate a...Ch. 5 - Prob. 5.32PCh. 5 - Prob. 5.33PCh. 5 - A 0.001 in. BCC iron foil is used to separate a...Ch. 5 - Prob. 5.35PCh. 5 - Prob. 5.36PCh. 5 - Prob. 5.37PCh. 5 - Prob. 5.38PCh. 5 - Prob. 5.39PCh. 5 - Prob. 5.40PCh. 5 - Prob. 5.41PCh. 5 - Prob. 5.42PCh. 5 - Prob. 5.43PCh. 5 - Prob. 5.44PCh. 5 - Prob. 5.45PCh. 5 - Prob. 5.46PCh. 5 - Prob. 5.47PCh. 5 - Prob. 5.48PCh. 5 - Pure zinc is to be diffused into copper by dipping...Ch. 5 - Nitriding is a process in which nitrogen is...Ch. 5 - Determine the carburizing time necessary to...Ch. 5 - Prob. 5.52PCh. 5 - Prob. 5.53PCh. 5 - Prob. 5.54PCh. 5 - Prob. 5.55PCh. 5 - Prob. 5.56PCh. 5 - Prob. 5.57PCh. 5 - Prob. 5.58PCh. 5 - Compare the rate at which oxygen ions diffuse in...Ch. 5 - Prob. 5.60PCh. 5 - Prob. 5.61PCh. 5 - Prob. 5.62PCh. 5 - Prob. 5.63PCh. 5 - Prob. 5.64PCh. 5 - Prob. 5.65PCh. 5 - A 0.80% C steel must operate at 950°C in an...Ch. 5 - Prob. 5.67PCh. 5 - Prob. 5.68PCh. 5 - Prob. 5.69PCh. 5 - Prob. 5.70PCh. 5 - Prob. 5.71PCh. 5 - Prob. 5.72PCh. 5 - Most metals and alloys can be processed using the...Ch. 5 - Prob. 5.74PCh. 5 - Prob. 5.75PCh. 5 - Prob. 5.76PCh. 5 - A ceramic part made from MgO is sintered...Ch. 5 - Prob. 5.78PCh. 5 - What are the advantages of using hot pressing and...Ch. 5 - Prob. 5.80PCh. 5 - Prob. 5.81DPCh. 5 - Design a spherical tank, with a will thickness of...Ch. 5 - Prob. 5.83DPCh. 5 - Prob. 5.84DPCh. 5 - Prob. 5.85DPCh. 5 - Prob. 5.86CPCh. 5 - Prob. 5.87CPCh. 5 - Prob. 5.88CPCh. 5 - Prob. 5.1KP
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Need a deep-dive on the concept behind this application? Look no further. Learn more about this topic, mechanical-engineering and related others by exploring similar questions and additional content below.Similar questions
- Diffusion of carbon into BCC iron for 12 hours at a temperature of 500 °C results in a carbon concentration of 0.2 wt% at a depth 2 mm from the surface. How long would it take to get a concentration of 0.2 wt% at a depth 3 mm from the surface at 500 °C?arrow_forward(c) Consider an alloy that is undergoing carburizing process, initially has a uniform carbon concentration of 0.27 wt% and is to be treated at 950oC (1750oF). If the concentration of carbon at the surface is suddenly brought to and maintained at 1.32 wt%, how long will it take to achieve a carbon content of 0.85% at a position 0.7 mm below the surface? The diffusion coefficient for carbon in iron at this temperature is 1.6 x 10-11 m2/s; assume that the steel piece is semi-finite.arrow_forwardThe outer surface of a steel alloy is to be hardened by increasing its carbon content. The carbon is to be supplied from an external carbon-rich atmosphere, which is maintained at an elevated temperature. A diffusion heat treatment at 837°C for 11 min increases the carbon concentration to 0.79 wt% at a position 1.9 mm below the surface. Estimate the diffusion time required at 680°C to achieve this same concentration also at a 1.9 mm position. Assume that the surface carbon content is the same for both heat treatments, which is maintained constant. The preexponential and activation energy values for the diffusion of carbon in the iron are 8.1 x 108 m²/s and 75.9 kJ/mol, respectively. i minarrow_forward
- why diffusion coefficient of caarbon inBCC and FCC iron at temperature 912 is different?arrow_forwardThe outer surface of a steel gear is to be hardened by increasing its carbon content. The carbon is to be supplied from an external carbon-rich atmosphere, which is maintained at an elevated temperature. A diffusion heat treatment at 850 °C (1123 K) for 30 min increases the carbon concentration to 0.90 wt% at a position 1.0 mm below the surface. Estimate the diffusion time required at 700 °C (973 K) to achieve this same concentration also at a 1.0-mm position. Assume that the surface carbon content is the same for both heat treatments, which is maintained constant. Use the diffusion data in Table 5.2 for C diffusion in -Fe. Hint: before trying to solve this using brute force, consider what is changing from the first process to the second process and how that impacts the equation for diffusion.arrow_forward6. (20%) Pure zinc is to be diffused into the copper by dipping copper into molten zinc at 450°C. Calculate how long would take to obtain 10wt% zinc at a depth of 0.5 mm beneath the copper surface. Is this commercially feasible? What practical problems might arise if we raise the temperature to 1000°C ? Use Table below for error function values as needed. At 450°C, the diffusion coefficient D = 6.3 10-17 m²/s.arrow_forward
- (c) A 1020 steel gear is carburized at 927°C and gives the surface carbon concentration maintained at 1.2 wt%. After 8 hours, the concentration of carbon is 0.4 wt%. Note: D (C in y iron) at 927°C = 1.28 × 10*1" m²/s. Determine the depth of the carbon diffuse to the gear steel after 8 hours. (d) State the importance of case hardening in gear steel components in the steel metal industry.arrow_forwardThe figure below shows five different steady-state concentration profiles from five separate tests, which had the same gas across identical membranes at the same temperature. Rank the diffusion flux of the five concentration profiles from lowest to highest. Using bullet points explain your answer. C(x)' (a) (b) (c) (d) (e) Membrane Thicknessarrow_forwardCompare the diffusion coefficients (in cm²/s) of nitrogen in BCC and FCC iron at the allotropic transformation temperature of 912°C. Decc -153606 X Your response differs from the correct answer by more than 10%. Double check your calculations, cm²/s -1976-7 Dicc x Your response differs significantly from the correct answer. Rework your solution from the beginning and check each step carefully. cm2/sarrow_forward
- Consider an alloy that is undergoing carburizing process, initially has a uniform carbon concentration of 0.27 wt% and is to be treated at 950°C (1750°F). If the concentration of carbon at the surface is suddenly brought to and maintained at 1.32 (c) wt%, how long will it take to achieve a carbon content of 0.85% at a position 0.7 mm below the surface? The diffusion coefficient for carbon in iron at this temperature is 1.6 x 10-11 m2/s; assume that the steel piece is semi-finite.arrow_forwardCompute diffusion coefficients for the interdiffusion of carbon in both (a) α-iron (BCC) and (b) γ-iron (FCC) at 1000˚C. Assume that D0 for the interdiffusion of carbon in α-iron and in γ-iron are 1.1 × 10-6 and 2.3 × 10-5 m2/s, respectively, and that Qd are 80 and 148 kJ/mol, respectively.arrow_forwardWhat temperature is required to obtain 0.4%C at a distance of 0.3 mm beneath the surface of a 0.22% C steel in 2h, when 1.1% C is present at the surface? Assume that the iron is FCC. (Please see figure 5.12 below for diffusion coefficient data. Please use your notes for a table of erf() function values table of erf() fun Diffusion coefficient D (cm²/s) 10-3 !! ! ! ! ! 10- 10-5 10-9 10-10 10-11 10-12 10-13 10-14 Temperature (°C) 2000 1500 1200 1000 900 800 700 600 wwwwwwwwwwwwwww in graphite Mg in MgO Ca in CaO H in FCC iron Cin FCC iron Fe in FCC iron Fe in BCC iron H in BCC iron 104 T(K) C in BCC iron Fe in FeO 500 10-15 4 5 6 7 8 9 10 11 12 13 Figure 5-12 The diffusion coefficient D as a function of reciprocal temperature for some metals and ceramics. In this Arrhenius plot, D represents the rate of the diffusion process. A steep slope denotes a high activation energy.arrow_forward
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Introduction to Diffusion in Solids; Author: Engineering and Design Solutions;https://www.youtube.com/watch?v=K_1QmKJvNjc;License: Standard youtube license