Temper-Resistance of Cr-W-Mo-V High Carbon Medium Alloy Steel and its Hardness Forecast

Abstract

The temper-resistance temperature of Cr-W-Mo-V high carbon medium alloy steels is in a range at 200°C-300°C. Along with increasing C and alloy contents in particular Cr content of the steels, the temper-resistance is boost up gradually and maximal hardness arrives to 63-64HRC at temperature 200°C-250°C. When budget for quenching matrix composition and undissolved carbides, the actual quenching temperature TH is corresponding to the calculational temperature TC by phase-equilibrium thermodynamics as TH=TC + (1000°C－TC)/6.5, and roughly, the calculational temperature is less 20°C than actual temperature when quenching at 800°C-890°C. The carbides precipitation during tempering is agreement with phase equilibrium thermodynamic calculation incompletely, thereinto (Fe,Cr)3C carbide precipitation is leading at 200°C-250°C.The higher hardness at temper-resistance temperature is corresponding to tempering temperature of remnant austenitic decomposing acutely.The tempering hardness can be estimated on the basis of quenching hardness calculation. The quenching hardness value can be obtained from HC=α（1+β）/(0.00915α+0.00527), in which α is the square root of carbon content in the matrix and β is correction coefficient of solid solution strengthening.