Abstract: Cobalt-based Stellite 6B is a wrought alloy with excellent wear resistance combined with guaranteed mechanical properties such as tensile plasticity and impact toughness. Considering that there is a certain risk of radioactive contamination from the cobalt bearing debris in the nuclear reactors, the design of the grippers requires that the wear loss of the grippers made of the cobalt-based stellite alloys should be controlled to a critical mass during the srvice life-time, and also requires to ensure the material with tolerable mechanical properties simultaneously. Many studies haved shown that under determined frictional conditions, the wear resistance and mechanical properties of stellite alloys highly depend on their microstructures. Therefore, it s necessary to investigate the microstructure variations and subsequently wearing resistance and mechanical properties of the employed Stellite 6B after solution treatments at different elevated temperatures. In this paper, the microstructure details of the Stellite 6B alloy solution treated at temperatures ranging from 1 000 ℃ to 1 200 ℃ were observed by SEM back-scattered electron images and electron back scatter diffractions in scanning electron microscope and TEM techniques. Then, the alloy’s hardness and impact toughness were evaluated, and at meanwhile, 107 whirl wear loss of the friction pair of the studied alloy against to GH5605 alloy were measured by block on ring sliding wear test method. The microstructure observation and mechanical tests indicate that the Stellite 6B alloy presents an uniform and fine grain matrix and equiaxed primary M7C3-type carbides after solid solution treatment at 1 200 ℃~1 150 ℃ and exhibited favorable impact toughness. While, as the solid solution temperature decreased, increasing amount of secondary M23C6 carbides precipitated mostly along the grain boundaries and consequently increased the hardness slightly but depressed the impact toughness sensibly. The fracture surface observation confirmed that the continuity of grain boundary carbides was the main microstructural factor leading to the decrease in impact toughness. Wearing test results showed that the average friction coefficient gradually decreased as the solution temperature decreased. Meanwhile, 107 whirl wear loss of the studied alloy decreases a little when lowering the solution temperature from 1 200 ℃ to 1 150 ℃ and notablely droped by more significantl amount as reducing the solution temperature further. Then, it was good to identify that the solid solution treatment at 1 100 ℃ can endow the Stellite 6B alloy with excellent wear resistance and tolerable impact toughness. The back-scattered electron images and EDS analysis of the worn surface indicate that after the wearing test, the surfaces of the friction pair alloy GH5605 were covered with a large amount of Stellite 6B alloy debris, demonstrating that the major wearing mechanism of the two cobalt based alloy mating pairs was adhesive wear. The electron back scatter diffraction patterns of the worn samples showed high density dislocations in the outer layer that induced certain amount of hcp structure ε phase in the metastable fcc structured matrix. It was noteworthy that the amount of ε phase was rather significant in the worn samples solution-treated at 1 100 ℃ or lower temperatures but only minute quantity of ε phase was visible in TEM observation. This suggest that the cumulative strain could induce the martensitic transformation in the metastable fcc structured matrix of lower temperature solution-treated samples, so that the improved anti-adhesive wear performance of the Stallite 6B alloy could be attributed to the increased amont of hcp structure ε phase in the matrix ever solution treated at lower temperatures.