Posted: September 13th, 2017

Material and Processes

Paper, Order, or Assignment Requirements

 

 

Can you please answer all the question shown on the paper attached
and make sure its been answer on your own word. you can use every source to answer such as online sources,books ..
the books been used in course are :
Course Material
Book
Author
Kalpakjian, S.
Publishing Year
2003
Title
Manufacturing Processes for Engineering Materials
Subtitle
Edition
4th
Publisher
Addison Wesley
ISBN
0-201-50806-0

———————–
Course Material
Book
Author
Malkin, S.
Publishing Year
1991
Title
Grinding Technology
Subtitle
Edition
Publisher
Ellis Horwood
ISBN
0-853-12756-5

———————
Course Material
Book
Author
Degarmo E.P., Black J.T. and Kohser R.A.
Publishing Year
2000
Title
Materials and Processes in Manufacturing
Subtitle
Edition
8th
Publisher
Wiley
ISBN
0-471-36679-X

5119ENG VLE Test

Module Name: MATERIALS AND PROCESSES

Module Code: 6161ENG

Weighting: 15% of Final Module Mark

Lecturer: Dr Lisa B Li

Issue Date: 30/10/2014

Hand-in Date: 27/11/2014 (to be submitted as a pdf file via TurnItIn)

Feedback: Feedback will be given when your coursework is returned to you.

1. Iron transform from BCC (α, low temperature form) to FCC (γ, high temperature form) at

912°C. Calculate the percent density change associated with this transformation. Use

atomic radius of Fe = 0.124 nm. (5Marks)

2. What are dislocations? What do dislocations do? Describe edge dislocation and screw

dislocation. (6 Marks)

3. Do the explanations of these experimental observations involve the concept of

dislocations? Explain. (6 Marks)

1. A) The yield stress of a material is lower than that calculated from assuming a perfect

lattice

1. B) In some cases, the stress required to continue plastic deformation increases as

deformation proceeds

4. What is work hardening? The effects of cold work (strain hardening) on the properties of

an aluminium alloy are shown in Figure Q4. Assuming this alloy has a single phase

microstructure (aluminium solid solution, or Al). Sketch a schematic stress-strain

diagram for the alloy at 0, 40 and 80 percent cold work.(10 Marks)

5. For a carbon steel and an aluminium alloy, the data in the table gives grain size and yield

strength:

Carbon steel Aluminium alloy

d(μm) σy(MPa) d(μm) σy(MPa)

406 93 42 223

106 129 16 225

75 145 11 225

43 158 8.5 226

30 189 5.0 231

16 233 3.1 238

1. a) Show that the yield strengths of this steel and aluminium alloy obey the Hall-Petch

relationship. Determine o and ky for each material. (4 Marks)

1. b) Certain micro-alloyed steels contain small additions of vanadium or niobium that

permit the grain size to be reduced to about 2μm if the processing of the steel is

carefully controlled. Likewise, advanced aluminium alloys containing special types of

particles can be processed to yield a grain size of about 2μm. Suppose we reduce the grain size of steel and aluminium from 150μm to 2μm by such processing. What is the

relative increase in strength in each material? Comment on the significance of your

answer. (6 Marks)

6. Explain the following definitions: phase, binary phase diagram, metal alloy. (3 Marks)
7. What is eutectic reaction? What is eutectoid reaction? Give examples. (6 Marks)
8. Use the Pb–Sn diagram in figure Q8 to answer the following questions.

(a) What are the values of the two state variables at point 1? (2 Marks)

Composition: _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _

Temperature: _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ __ _ _ _ _ _

(b) Mark the constitution points for Pb–70 wt% Sn and Pb–20 wt% Sn alloys at 200°C.

What does the alloy consist of in each case? (2 Marks)

Pb–70wt%Sn: _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _

Pb–20wt%Sn: _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ __ _ _ _ _

(c) The alloy corresponding initially to the constitution point 1 is cooled very slowly to

room temperature. (3 Marks)

At which temperatures do changes in the number or type of phases occur?

_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _

What phases are present at point 2? _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _

What phases are present at point 3? _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _

(d) Similarly, the alloy corresponding to the constitution point 4 is cooled to room

temperature. Identify the following: (4 Marks)

Initial composition and temperature: _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _

Initial phase(s): _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _

Temperature at which change of phase occurs: _ _ _ _ _ _ _ _ _ _ _ _ _ _

Final phase(s): _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _

9. Using the following data, calculate the volume fraction of the pro-eutectic beta phase

and eutectic (α+β) at the eutectic temperature, for an alloy of composition 75 wt% Ag.

Assume equilibrium conditions. (8 Marks)

At eutectic temp: eutectic composition = 71.9 wt% Ag, maximum solid solubility of Cu in

Ag = 8.8 wt% Cu, density Ag = 10490 kg/m3

, density Cu = 8920 kg/m3

1. What phases can be found in Fe-Fe3C phase diagram? (2 Marks)
2. a) α-Ferrite
3. b) Perlite
4. c) Cementite
5. d) Martensite
6. e) δ-Ferrite
7. f) Austenite
8. Describe and draw the microstructure components in steels that are hypoeutectoid,

eutectoid and hypereutectoid.(8 Marks)12. A) On the basis of microstructure, briefly explain why gray iron is brittle and weak in

tension. (2 Marks)

1. B) Brief microstructure of different type of cast iron and their applications. (12 Marks)
2. Give the temperature range over which it is possible to austenitize each of the following

iron-carbon alloys during a normalizing heat treatment: (a) 0.20wt%C, (b) 0.76wt%C, and

(c) 0.95wt%C. (3points)

4. Figure shows the isothermal transformation diagram for an iron-carbon alloy of eutectoid

composition, specify the nature of the final microstructure (in terms of microconstituents

present and approximate percentages of each) of a small specimen that has been subjected

to the following time-temperature treatments. In each case assume that the specimen

begins at 760°C and that it has been held at this temperature long enough to have achieved

a complete and homogeneous austenitic structure. (8 Marks)

(a) Rapidly cool to590°C, hold for 3 s, rapidly cool to 450°C, hold for 10 s, then quench to

room temperature.

(b) Cool rapidly to 400°C, hold for 2 s, and then quench to room temperature.

(c) Cool rapidly to 400°C, hold for 180 s, and then quench to room temperature.