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

A. GUALCO, H. G. SVOBODA, E. S. SURIAN, L. A. DE VEDIA

Welding International

Taylor & Francis

Lugar: Londres; Año: 2010 vol. 24 p. 258 - 265

0950-7116

The effect of different post weld heat treatments on mechanical properties and microstructure of martensítica MCAW deposits was studied. The deposit was welded in the flat welding position, on 375x75x19 mm 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 to 680ºC for two hours. Chemical composition, Vickers microhardness and wear properties with AMSLER tests (measuring the weight loss at different traveled distances up to 5000 m, with 1250 N load) were determined. The microstructure was studied with both optical and electron microscopy and X ray diffraction. In the as welded condition the microstructure was principally composed by 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 decomposition of retained austenite to martensite and carbide precipitation associated to the tempering of martensite A secondary hardness effect was detected with maximum hardness of 710 HV for 550ºC heat treatment temperature. Wear rates for the different conditions were obtained and mathematical expressions were developed. For each case wear mechanisms were analyzed.