Explain why martensitic steels are usually tempered and desc

Explain why martensitic steels are usually tempered and describe what structures steel marten site evolve to during tempering.

Solution

Martensite is a very strong phase but it is normally very brittle so it is necessary to modify the mechanical properties by heat treatment in the range 150-700°C, This process is called Tempering.

Martensite is a highly supersaturated solid solution of carbon in iron, which, during tempering, rejects carbon in the form of finely divided carbide phases. The end result of tempering is a fine dispersion of carbides in an -iron matrix, which often bears little structural similarity to the original as-quenched martensite.