22) What type of abrasives are used in honing cast iron and non-ferrous materials?

23) Which method of surface hardening, the surface remains free from scales?

24) What is the process if the steel is heated above critical temperature and soaking it for sufficient time and cooling it very slowly within furnace?

25) What is the process to refine the structure of steel component?

26) Which method of surface hardening is done in a heated salt bath?