Question

Please answer 5 questions from below:

Q1-Chromium electroplate needs to be at least 50 microns thick, OR have an underlayer, to from corrosion. Why is thati protect the substrate

Q2-Name the strongest copper alloy

Q3-. Can the austenite (FCC) or the ferrite (BCC) structure of iron dissolve more carbon? Why?

Q4. Why should gray cast iron NOT be used to cast church bells?

Q5-Give me three differences between carburizing and nitriding

Q6 -What is the difference between ASTM and 15O?

Q7 -Properly heat treated, which of the five generally recognized families of stainless steel are hardest?

Q8 -In fatigue nomenclature, what is meant by "R ratio

Q9. I can mix in reinforcement like silicon carbide powder when 'm electroplating with chromium or nickel, but I cannot when I am anodizing aluminum. Why is that?

Q10. Why are castings more commonly measured using Brinell hardness than Rockwell hardness?

Q11. What is the difference between a direct, an indirect, and a derived material property?

Q12. Fracture toughness testing is more complicated and more expensive than Charpy testing. What does fracture toughness testing give us that makes it worth the added cost? Q13. In a precipitation hardening material, it's softest right after the quench. Yet a quench and temper steel is hardest right after the quench. Why so for each?

Q14. Comparing the naming systems for steel, copper, aluminum, titanium, and nickel alloys, which one is the most controlled?

Q15. Look at the two 8-H curves on the back page. Would you use Adamantium or Carbonite for a refrigerator magnet? Why?

Answer 1

Ans. 2] Beryllium-Copper Alloy is the strongest copper alloy.

Ans. 3] The austenite (FCC) structure can dissolve more carbon than the ferrite structure because in austenite, octahedral interstitial sites are much greater than the tetrahedral interstitial sites while in the ferrite structure, they are nearly equal to each other. More number of sites share the total open space. Thus, interstitial space in FCC is much greater than in BCC.

Ans. 5] Difference between Carburizing and Nitriding:

1. Carburizing is a process of heat treatment in which carbon gets diffused into the metal surface to form a hardened surface while Nitriding is a heat treatment process in which nitrogen gets diffused into the metal surface to form a hardened surface.
2. In carburizing, a carbonaceous environment is used while in nitriding environment containing nitrogen is used.
3. Carburizing requires very high temperatures while nitriding requires low temperatures.

Ans. 6] The ISO 10350:1993 mechanical test standards cannot be relied upon when it comes to providing uniform mechanical test standards at a global scale because ISO has changed many procedures to conduct mechanical tests. It has also changed the specimen geometries and the equipment used for testing. Also, not all mechanical characteristics are described for polymeric materials by the ISO 10350:1993 method.

On the other hand, the mechanical properties provided by ASTM are more realistic to the applications, are described in more detail and are in alignment with the requirements of the industry. In addition, the mechanical test standards provided by ASTM have given good results much longer than those provided by ISO.

Ans. 8] In fatigue nomenclature, the R-ratio is defined as the minimum peak stress divided by the maximum peak stress. The equation for the same has been given below: