Tempered martensite

A microstructure produced by tempering brittle martensite, causing carbon to precipitate as ultra-fine carbides. It relieves internal stresses and achieves a favorable strength-to-toughness ratio.

Tempering after welding is important to transform the hard, brittle martensite back into a tougher structure. You heat the part to a moderate temperature and hold it there for a while so the carbon can distribute evenly in the lattice. The result is tougher and less prone to cracking. If you cool too quickly or quench it directly in water, you'll make the structure hard and brittle again.

MetallurgieSchweißtechnik