Evaluation of the Behaviour and Properties of a High-Si Steel Processed Using Direct Quenching and Partitioning

Abstract

An experimental steel containing in weight % 0.2C-2.0Mn-1.5Si-0.6Cr has been laboratory hot rolled, direct quenched into the Ms- Mfrange and partitioning annealed in order to explore new possibilities for making 1100 MPa yield strength structural steels with better combinations of strength, ductility and impact toughness. Two austenite states prior to quenching were investigated: recrystallized and strained. Gleeble simulations were used to determine appropriate cooling rates and cooling stop temperatures for obtaining martensite fractions in the range 70-90%. Desired martensite - austenite microstructures were achieved, and ductility and impact toughness were better than those obtained via the simple direct quenching of a lower carbon steel in the same strength class.