True-False Questions T/F 1. Dislocations can be seen with the naked eye. ___ 2.

Question

True-False Questions T/F

1. Dislocations can be seen with the naked eye. ___

2. Slip occurs along the planes of maximum atomic density. ___

3. Increasing the temperature of a metal lowers its elastic modulus ___

4. Decreasing the temperature of a metal increases it yield strength. ___

5. A direct correlation exists between the UTS and elastic modulus. ___

6. Increasing the molecular weight of a polymer increases its strength. ___

7. Metal alloys can melt at one discrete temperature. ___

8. Crystalline polymers are transparent. ___

9. Ceramics are tougher than metals. ___

10. The cope of a sand casting mold is traditionally placed under the drag. ___

11. Investment casting produces a better surface finish than sand casting. ___

12. It is easier to cast steel than aluminum. ___

13. The cost of labor for sand casting is lower than that of an investment casting. ___

14. Forming the head of a bolt is a forging operation. ___

15. Sand casting of a connecting rod is cheaper than forging it. ___

16. Metal spheres can be produced by extrusion. ___

17. Sheets of glass are formed by floating the glass on molten tin. ___

18. Stereolilthographic parts are formed from a UV curable liquid. ___

19. It is not possible to integrate rapid prototypes into other manufacturing processes. ___

20. Injection molding is cheaper than rotational molding. ___

Multiple Choice Questions (Circle your answers)

1. Which answer describes how dislocations affect the theoretical strength of a perfect material?

a. Lowers the theoretical strength

b. Raises the theoretical strength

c. No change in the theoretical strength

2. What effect does increasing strain rate have on the tensile strength of a material?

a. Decreases the tensile strength

b. Increases the tensile strength

c. No change in the tensile strength

3. What is the hardest material on the earth?

a. Cobalt

b. Nanocrystalline Au

c. Boron Nitride

d. Diamond

4. A material is subjected to the same alternating loading for many cycles. After the 100,00th cycle the piece breaks by fracturing. This piece failed in a manner consistent with a

a. Creep failure

b. Fatigue failure

c. Thermal shock failure

d. Impact failure

5. Ductile-to-brittle transitions are typically seen in metals with an:

a. FCC crystal structure

b. HCP crystal structure

c. BCC crystal structure

d. BCT crystal structure

6. Which type of material has the highest thermal conductivity on average?

a. Composites

b. Ceramics

c. Plastics

d. Metals

7. The primary bonds of a polymer are:

a. Covalent

b. Metallic

c. van der Waals

d. Hydrogen

8. Which part defines the hollow cavity of a casting?

a. Sprue

b. Gate

c. Core

d. Cope

9. Plastic soda bottles are made from a

a. Ingot

b. Parison

c. Bloom

d. Core

10. Most thermoplastic products are made by

a. Injection molding

b. Casting

c. Rotational molding

d. Polymer extrusion

Qualitative Problems (Note: Actual exam may have more or less problems in this section)

1. Considering the three major types of materials (ceramics, plastics, and metals) rank them in order of decreasing stiffness.

2. Why are titanium and aluminum common materials used in aircraft?

3. Name 6 products that are made from stainless steel. Why are these products made of stainless steel and not a plain carbon steel?

4. Why are networked polymers so much stronger than branched polymers?

5. Name two attractive material properties of composites. Why are composites not used in more manufactured products?

6. Name two methods of decreasing the grain size in a casting. Why are smaller grains typically desired?

7. Name six casting defects.

Quantitative Problems (Note: Actual exam may have more problems in this section)

1. A rectangular bar of Al, 1 m long, is subjected to a compressive load of 20 kN. If its cross sectional dimensions are 1 in. by 2 in. what is the engineering stress and engineering strain?

2. An open die forging process is used to compress a cylinder of 6061-O Al. The cylinderâs initial height is 125 mm and final height will be 70 mm. If the initial diameter of the cylinder is 100 mm and the coefficient of friction for the process is 0.3, calculate the forging force necessary to compress the cylinder.

Explanation / Answer

You have indeed asked a very very long question for 1500 point, still, i am answering it one by one, i am a metallurgical enginner.

First True and false:

F,T,T,F,F,T,F,T,T,T,T,F,T,T,F,F,F,T,T,T(i have doubt in 2-3 answers but rest is completly fine)

MCQ

1a,2b,3d,4b,5bc,6d,7a,8c,9d,10a.

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