What is the relationship between the impact energy and the c

What is the relationship between the impact energy and the change in cross-section for fractured metals? Mow about for polymers? What type of fracture do you think that you would get if you impact tested polycarbonate at -50C, at 100C, and at 200C? Why? Why do they use 316 stainless steel for cryogenic applications, and not 430? Mo, for example, has great high-temperature performance (e.g., potential use as a turbine blade material for aircraft engines). What is the problem with using it?

Solution

PART -- 1> The relationship is that of loss to impact energy to change the cross-section at the notch area of the metal specimen under fracture. Specimens of metals are usually square, and polymers are usually rectangular being struck perpendicular to the long axis of the rectangle.

PART -- 2> (At -50C --- Brittle fracture), (at 100C --- Ductile fracture) and (at 200C --- Ductile fracture). This is because as temperature increases, it shows good impact resistance.

PART – 3> The type 430 stainless steel has limited weldability and should not be used in the as welded condition for dynamic or impact loaded structures. Being a ferritic material, 430 is liable to brittle fracture at sub-zero temperatures, and cannot be used in cryogenic applications. The type 316 stainless steel shows good corrosion and pitting resistance. It has good weldability and hence is used in cryogenic applications and medical industry.

PART -- 4> Mo though having great high temperature performance has poor oxidation resistance and shows brittleness at such temperatures.