ACICULAR MARTENSTTE IN LASER TREATED GREY CAST IRON

Laser quenched microstructure of HT 21-40 grey cast iron Was studied by transmission electron microscopy. Results indicated that the structure is consisted of fine acicular martensite and ultrafine grained austenite. The carbon content of austenite is about 1.8%, that can also be transformed into fine acicular martensite when cooled in liquid nitrogen.