Austempering of DIN CK50 and DIN 62SiMnCr4 In Molten Lead Bath

Abstract

This work aims to study the ability of austempering DIN CK50 and DIN 62SiMnCr4 steels. Both steels were heated to austenitising temperature and then quenched in a molten metal bath (pure lead) at temperature below the nose of the TTT curves for both steels. Results showed that austempering at 350oC and 400oC for 30 and 15 minutes are the best for above steels respectively, where strength was increased. It was also shown that increasing holding (soaking) time decreases both hardness and strength and increasing elongation percentage. Microstructure examination showed that the majority of microstructures obtained from austempering vary from bainite and pearlite and ferrite for carbon steel to a mixture of bainite, retained austenite and martensite for the alloy steel.