Laser surface treatment of AiSi 416 machinable martensitic stainless steels

Laser surface treatment was carried out on AISI 416 machinable martensitic stainless steel containing 0.225 wt.% sulfur. Nd:YAG laser of a 2.2-KW continuous wave was used. The aim was to compare the physical properties achieved by this type of selective surface treatment and the conventional heat treatment. Laser power of different values (700 and 1000 watt) with corresponding four different laser scanning speeds (50,100,200 and 300 cm/min) was adopted to reach the optimum condition for impact toughness and wear resistance for laser heat treated (LHT) samples. The 0 °C-impact energy of LHT samples indicated higher values compared to the conventionally heat treated (CHT) samples. This was accompanied by the formation of a hard surface layer and a soft interior base metal. Microhardness was studied to determine the variation of hardness values with respect to the depth under the treated surface. The wear resistance at the surface was enhanced considerably. Also, microstructure examination was carried on using optical and scanning electron microscopes.