Efecto del tratamiento térmico posterior sobre la resistencia al desgaste de depósitos de soldadura martensíticos para recargue

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

Belo Horizonte, Brasil

Congreso; XXXII CONSOLDA; 2006

Asociación Brasilera de Soldadura

  The effect of different post weld heat treatments on mechanical properties and microstructure of martensítica MCAW deposits was studied. The deposits were welded in the flat welding position, on 375x75x19 mm SAE 1010 plates, 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. Tempering of examined steels in the temperature range analyzed resulted in carbides precipitation and austenite to martensite transformation. A secondary hardness effect was detected. Maximum hardness of 710 HV was found at 550ºC of heat treatment temperature. Waste rates for the different conditions were determined.