Abrasive Materials for Grinding Hardened Tool Steel

Which abrasive material is most appropriate for grinding hardened tool steel?

(a) aluminum oxide
(b) cubic boron nitride
(c) diamond
(d) silicon carbide

Answer:

The most suitable abrasive material for grinding hardened tool steel is cubic boron nitride.

In the context of grinding hardened tool steel, the most suitable abrasive material is cubic boron nitride (option b). Cubic boron nitride has a hardness rating that is second only to that of diamond, but unlike diamond, it does not chemically react with iron group metals (like steel), rendering it more effective for this specific purpose.

Aluminum oxide and silicon carbide are more appropriate for softer materials, while diamond, although extremely hard, can carbonize with steel, leading to reduced tool life.