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?

27) Which key has rectangular cross section is fit into keyway cut on both shaft and hub?

28) Which key is useful for fitting on tapered shafts?