Effect of Heat Treatment on Microstructure and Mechanical Properties of Cr31 Hypereutectic Cast Iron

The effect of destabilization at (960°C,1000°C,1050°C) followed by sub-critical heat treatment (SCHT) at (260°C, 450°C, 550°C) on microstructure and mechanical properties of a hypereutectic chromium cast iron containing 31 wt.% Cr was investigated. The response of the microstructure of the specimens differed significantly to heat treatment. With increasing destabilization temperature, the amount of retained austenite increased and it became more stable during following SCHT. The peak values of bulk hardness deceased with increasing destabilization temperature, while higher SCHT was needed to reach the hardness maximum. The hardness and erosion wear property of the specimens destabilization at 960°C or 1000°C deteriorated after SCHT at 550°C due to the formation of ferrite/carbide product, which was not found in the specimens destabilization at 1050°C followed by SCHT at 550°C. The specimen destabilization at 960°C + SCHT at 260°C performed best erosion wear resistance with matrix of martensite containing little austenite.