Question

Problem: Utilize the Tabulation Error Function Value Table from your Examination Booklet.

--Given Values--
Concentration of Nitrogen (wt%): = 0.38
Position in mm = 8.5
Diffusion Coefficient for Nitrogen in Iron at 700℃ = 9.70E-10
Nitrogen in Iron Heat Treatment Time (hours): = 13
Carburizing Time (hrs): = 10
Steel Alloy Case Depth (mm): = 3
Steel Alloy New Case Depth (mm) = 8.8
Activation Energy kJ/mol: = 107
Temperature for Problem 3 (Celsius): = 821
- = Data for Problem 4
Temperature in C: = 604
Diffusivity (m²/s) = 5.73E-14
Temperature in C: = 698
Diffusivity (m²/s) = 3.64E-13

Problem 1:

Nitrogen from a gaseous phase is to be diffused into pure iron at 700℃. If the surface concentration is maintained at the level listed above, what will be the concentration (in weight percent) with the given case and heat treatment time? The diffusion coefficient for nitrogen in iron at 700℃ is given above. (Round your answer to the ten thousandths place, 0.0000)

        Your Answer =

Problem 2:

For a steel alloy it has been determined that a carburizing heat treatment for the time, given above, will raise the carbon concentration to 0.42 wt% to the depth given from the surface. Estimate the time necessary to achieve the same concentration at the new position stated above for an identical steel and at the same carburizing temperature (in hours).

        Your Answer =

Problem 3:

The activation energy for the diffusion of species A in metal B is listed above. Calculate the diffusion coefficient at the temperature listed, given that the value of D at 1110 C is 6.2 x 10 ^-11 m²/s. Write your answer in scientific notation.

        Your Answer =

Problem 4: Part A

The diffusion coefficients for carbon in nickel are given at two temperatures above. Find the value of Do (m²/s):

        Your Answer =

Problem 4: Part B

The diffusion coefficients for carbon in nickel are given at two temperatures above. Find the value of Qd (kJ/mol):

        Your Answer =

Problem 4: Part C

What is the diffusivity, D, at 820 C?

        Your Answer =

Answer 1