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

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

LUBRICATION SCIENCE

JOHN WILEY & SONS LTD

Lugar: Londres; Año: 2013 vol. 25 p. 139 - 151

0954-0075

This paper analyzes the effects of post welding heat treatment on the tribological response of weld metals for hardfacing. Applied load in wear tests was also studied. The deposit was a martensitic steel obtained with a GMAW 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. On the contrary, the wearing mechanism of the samples tested at 2000 N was severe wear; being the heat treated ones more wear resistant with a higher friction coefficient 2 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. On the contrary, the wearing mechanism of the samples tested at 2000 N was severe wear; being the heat treated ones more wear resistant with a higher friction coefficient