Classification of microstructural changes in laser hardened steel surfaces

Three different steels with C contents of ∼0.2 wt.% and different contents of chromium, molybdenum and vanadium were similarly laser hardened after different preceding heat treatments. The laser-affected zones beneath the surface were characterised by microhardness, dislocation density, carbide type, size and distribution as well as grain size of the austenite. By a systematic study of the changes in microstructure of these laser-affected zones, the effective hardening mechanisms were separated and their influence on the material strength or the microhardness was classified.