found that the dissolved carbon content first decreases,reach a minimum value, then increase to a saturation limit.Explain this behavior,discuss the suitability of magnesia as a container,and suggest alternative approaches. (b)What factors determine the minimum coke rate(KgC per Kg Fe)required in blast furnace?Present a simplified model of the system(consider Fe,C and O only)and show the importance o f temperature profiles and relative coke reactivity. 34.Illustrate the phenomenon of latent hardening (overshoot)on a unit stereographic triangle for a tensile specimen of a fec single crystal. 35. Sketch stress-strain curves for brittle and ductile materials.Identify the elastic and plastic zones and briefly discuss the mechanisms by which fractures can occur in these regions.Your answer should discuss the meaning of terms such as "yield strength","ultimate tensile strength",ETC,which are frequently used to characterize the mechanical properties of materials. 36.List and discuss the various parameters that can influence the degree of strengthening attainable by precipitation hardening.What combination of parameters would you desire for optimum strengthening? 37.(a)Define hardness (b)Describe how one obtains hardness values using Rockwell,Brinell,and Vickers hardness testing equipment. (c)How does one determine which of the preceding methods to use? (d)What other methods of hardness testing are commonly used,and what are their advantages or disadvantages? 38.List some of the factors leading to a concern for brittle fracture of a metal engineering structure.What tests would you conduct to assure that the alloy had sufficient toughness?What are some of the limitations of these methods? 39.Give an explanation for aging and overaging for a precipitation-hardening alloy where the precipitate is never coherent with the matrix.Sketch a schematic phase diagram and indicate solution treating and aging ranges.Plot temperature versus time for the full heat treatment process.Sketch hardness versus time for a variety of different aging temperatures and explain the shape of curves. 40.a)What is the purpose of the following constituents of alloy steels? (i)Nickel (ii)Manganese (iii)Carbon (iv)Aluminumfound that the dissolved carbon content first decreases, reach a minimum value, then increase to a saturation limit. Explain this behavior, discuss the suitability of magnesia as a container, and suggest alternative approaches. (b) What factors determine the minimum coke rate (KgC per Kg Fe) required in blast furnace? Present a simplified model of the system (consider Fe, C and O only) and show the importance o f temperature profiles and relative coke reactivity. 34. Illustrate the phenomenon of latent hardening (overshoot) on a unit stereographic triangle for a tensile specimen of a fcc single crystal. 35. Sketch stress-strain curves for brittle and ductile materials. Identify the elastic and plastic zones and briefly discuss the mechanisms by which fractures can occur in these regions. Your answer should discuss the meaning of terms such as “yield strength”, ”ultimate tensile strength”, ETC, which are frequently used to characterize the mechanical properties of materials. 36. List and discuss the various parameters that can influence the degree of strengthening attainable by precipitation hardening. What combination of parameters would you desire for optimum strengthening? 37. (a) Define hardness (b) Describe how one obtains hardness values using Rockwell, Brinell, and Vickers hardness testing equipment. (c) How does one determine which of the preceding methods to use? (d) What other methods of hardness testing are commonly used, and what are their advantages or disadvantages? 38. List some of the factors leading to a concern for brittle fracture of a metal engineering structure. What tests would you conduct to assure that the alloy had sufficient toughness? What are some of the limitations of these methods? 39. Give an explanation for aging and overaging for a precipitation-hardening alloy where the precipitate is never coherent with the matrix. Sketch a schematic phase diagram and indicate solution treating and aging ranges. Plot temperature versus time for the full heat treatment process. Sketch hardness versus time for a variety of different aging temperatures and explain the shape of curves. 40. a) What is the purpose of the following constituents of alloy steels? ( ) Nickel ⅰ ( ) Manganese ⅱ ( ) Carbon ⅲ ( ) Aluminum ⅳ