Question

(a) Explain why a stainless steel containing 18wt % Cr is magnetic and is often used for knife blades, while a stainless steel containing 18 wt % Cr and 8 wt% Ni is not magnetic and is often used for stainless steel parts that need to be forged. (Pure Ni has an f.c.c. structure.)(b)Mo, W, and V all readily form small stable carbides. Explain why these elements can be used to produce tool steels thatretain their hardness at temperatures well above the temperature at which martensite would become over-tempered.(c)* A teaspoon is made of a single piece of stainless steel containing nickel. It is observed that the bowl of the spoon is not magnetic, but the handle is. Assume that all parts of the spoon are always at the same temperature, and that plastic deformation is used to form both the bowl and the handle. Explain the difference in properties(why is the crystal structure different).

Answer 1

Answer:

A stainless steel containing 18wt% of Chromium are magnetic and often used for knifes and blade because of the lattice structure of the stainless steel. The stainless steel are hard, due to the molecules in chromium are smaller and which makes them look like the molecules in wrought iron.

A stainless steel which contains 18wt%Cr and 8wt%Ni are not magnetic because of the lattice structure of the metal stainless steel. This steel are not very hard, due to the molecules of larger and looks like the molecules of a cast iron.

Tool steel that are mixed with small stable carbide retains their temperature when heated above the the normal temperature that can melt steel, because the steel has been mixed with carbide. Carbide is rich in carbon, and has a very high temperature which makes it able to retain heat. When carbides mixes with metal, it boiling point increase to a very high temperature.

The teaspoon that is made up of a single piece of stainless steel that contains only Nickel is made of two parts, the handle and the bowl. The bowl part are not magnetic because it is curved and very smooth, which changes the lattice structure of that part to become FCC. The handle part are magnetic because they are plain and are not very smooth, which makes the lattice structure to be BCC.