MET assignment 2

Spring 2020

MET 180

Structure and Properties of Materials

TAP 5

Date: Section:

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Grade: /100

1. Part 1: Structure, Properties of Materials and Phase Diagrams

(Type your answers in blue color)

Question 1: (16 points: 4 pts each)

A copper–nickel alloy of composition 40 wt % Ni – 60 wt % Cu is slowly heated from a temperature of 1100 °C.

Show your calculation details in your answer and draw lines on the phase diagram to label the phases and compositions.

a) At what temperature does the first liquid phase form?

b) What is the composition of this liquid phase (first liquid phase form)?

c) At what temperature does complete melting of the alloy occur?

d) What is the composition of the last solid remaining prior to complete melting?

Question 2: (12 points: 4 pts each)

For a copper–silver alloy of composition 30 wt % Ag – 70 wt % Cu and at 777 °C determine the followings:

Show your calculation details in your answer and draw lines on the phase diagram to label the phases and compositions.

a) Determine the mass fractions of α and β phases.

b) Determine the mass fractions of primary α and eutectic microconstituents.

c) Determine the mass fraction of eutectic α.

Question 3: (10 points: 5 pts each)

a) What is a Binary Eutectic System? Explain in detail and give an example eutectic reaction.

b) What are the eutectoid and the peritectic reactions? Explain and give example reaction for each one.

c)

Question 4: (12 points: 4 pts each)

Consider 4.0 kg of a 99.55 wt % Fe – 0.45 wt % C alloy that is cooled to a temperature just below the eutectoid.

Show your calculation details in your answer and draw lines on the phase diagram to label the phases and compositions.

a) How many kilograms of proeutectoid ferrite form?

b) How many kilograms of eutectoid ferrite form?

c) How many kilograms of cementite form?

Question 5: (10 points: 2 pts each)

State whether the following questions are True or False.

Type your answer (True or False) inside the box below for each question:

a) Ductility is a solid material's ability to deform under tensile stress; this is often characterized by the material's ability to be stretched into a wire.

Answer:

b) The ratio of the shear stress to the shear strain in the elastic range of torsion test is known as the Young’s Modulus or Modulus of Elasticity, E.

Answer:

c) The Engineering Stress, σ is defined as the ratio of the applied load to the instantaneous cross-sectional area of the test specimen.

Answer:

d) The area under the true stress–true strain curve up to fracture is known as the material’s toughness.

Answer:

e) The melting point of a solid is the temperature at which it changes state from liquid to gas at atmospheric pressure.

Answer:

f)

2. Part 2: Tensile and Hardness Testing of Metal Specimens

You will study different type of materials, testing methods and write a report about materials testing. You will analyze the tensile and hardness testing results of the selected materials. You will compare the initial hardness values of specimens before the tensile test to the ones after the tensile test in order to observe strain hardening behaviors of metals.

Figure 1: Tensile Test Machine

Figure 2. Hardness test machine.

You will study different type of materials, testing methods and write a report about materials testing.

1. You will read lab manual for the assigned test and summarize the experimental procedure.

2. You will find datasheets for the assigned materials and tabulate density, elastic modulus, yield strength, UTS, Poisson’s ratio and thermal conductivity

3. You can refer to the materials handbook to find more information about the materials properties. You may access the handbook at ACM library:

Cardarelli, F. (2008). Materials handbook: a concise desktop reference. Springer Science & Business Media.

a) Test Specimen Materials (8 Points)

(You will search for density, elastic modulus, yield strength, UTS, Poisson’s ratio and thermal conductivity for the below specimen materials and complete Table 1.)

Table 1 lists the physical and mechanical properties of specimen materials.

Table 1. Test specimens physical and mechanical properties

Specimen Material	Density (kg/m3)	Elastic Modulus (GPa)	Yield Strength (MPa)	Ultimate Tensile Strength (MPa)	Poisson’s Ratio (ν)	Thermal Conductivity (W/mK)
Aluminum
Brass
Copper
Steel

b) Experimental Procedure (8 Points)

(Read your TAP 2 report manual about the Vickers hardness test and briefly write down experimental procedure.).) (1 page)

c) Mechanical Properties (8 Points)

(Explain briefly all the mechanical properties measured using the tensile and hardness test methods. Write down the property and provide an explanation below) (1 page)

d) Experimental Results (8 Points)

The hardness test results for brass and aluminum before and after tensile testing is given in Table 2.

Table 2: Experimental results

Specimen	Hardness Before Tensile Test (HRA)	Hardness After Tensile Test (HRA)
Aluminum	38	46
Brass	44	52

Explain in detail why the hardness of the materials increase after the tensile test?

e) Analysis (8 Points)

Plot experimental hardness values before and after the tensile test, HRA versus materials bar diagram. Show the experimental results and specimen materials on the diagram. Label x and y axes.

Use MS Excel Bar chart to plot your diagram and copy the diagram here.

f) Tensile Test with a Factor of Safety (Bonus: 10 Points)

Calculate a diameter, D, to ensure that yield does not occur in the 1045 carbon steel rod below.

1045 carbon steel

σ

y

= 360 MPa

UTS = 565 MPa

F = 250 kN

D

L

o

· The factor of safety of N = 2.5.

· Yield strength is σy = 360 MPa

· Applied force F = 250 kN

σallowable

Type your answer below:

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Page 11 of 13

σworking = σ y N

σworking = σ y N