EFFECT OF HEAT TREATMENT AND LOADING ON TRIBOLOGIC BEHAVIOR OF WELDING DEPOSITS FOR HARDFACING

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

Río de Janeiro

Conferencia; First International Brazilian Conference on Tribology; 2010

ABM

This paper analyzes the effects of post welding heat treatment and applied load in wear tests on the tribological response of hard weld surfacing. The deposit was a martensitic steel obtained with a FCAW metal-cored wire under gas shielding of Ar-2%CO2 and 2 kJ/mm of heat input. Cross sections were obtained from the welded coupon and subjected at 550°C during 2 hours. These samples, together with the as welded specimens, constituted the system under study. Cross sections were also extracted for both conditions to determine chemical composition, microstructure characterization, micro-hardness measurements in addition to friction and metal-metal wear tests in pure sliding at 500, 1250 and 2000 N of applied load. A microstructure composed of martensite and retained austenite was observed for both conditions. The as welded sample presented 16% of retained austenite whereas the heat treated one 8%. Heat treated coupons showed secondary hardening associated with precipitation phenomena. In the specimens tested at 500 and 1250 N the wear mechanism was oxidative and the as welded specimens presented higher wear resistance and a higher friction coefficient. Regarding the tested samples at 2000 N, wearing mechanism was delamination and heat treated samples resulted more resistant with a higher friction coefficient.