Effect of post-weld heat treatment on the wear resistance of hardfacing martensitic steel deposits

Abstract

The effect of different post-weld heat treatments on the microstructure and wear resistance of martensitic deposits were studied. The deposit was welded using a metal-cored tubular wire, in the flat welding position, on a 375 × 75 × 19mm SAE 1010 plate, using 98% Ar-2% CO2 shielding gas mixture and with an average heat input of 2.8 kJ/mm. The samples were heat treated at temperatures between 500 and 6808C for 2 h. Chemical composition, Vicker's microhardness and wear properties with AMSLER tests in a sliding condition were determined. In the as welded condition, the microstructure was principally composed of martensite and retained austenite. Significant variations in wear resistance and hardness were measured for different tempering temperatures. For the different heat-treated conditions, it was observed that the decomposition of retained austenite to martensite and carbide precipitation was associated with the tempering of martensite. A secondary hardness effect was detected with maximum hardness of 710HV for 550°C heat treatment temperature. The best performance in wear test was obtained for this condition. Wear rates for the different conditions were obtained and mathematical expressions were developed. For each case, wear mechanisms were analyzed.