Effect of heat treatment condition on microstructure and mechanical properties of2.5 Ni cast steels

摘要

The effect of the cooling rate (WQ:Water-Quenching, AC: Air-Cooling and FC: Furnace-Cooling) after austenization on the microstructure and mechanical properties of 2.5%Ni cast steels was investigated. The WQ sample exhibited a fully bainite microstructure, while the AC and the FC samples exhibited a ferrite-bainite microstructure and ferrite-pearlite microstructure, respectively. The mechanical properties were significantly improved with increasing cooling rate after austenization. SEM fractography and EBSD measurement results showed that this improvement in mechanical properties was caused by grain refinement of the bainite microstructure.