Effect of tempering on microstructure and mechanical properties of cast iron rolls laser alloyed with C-B-W-Cr

Abstract

Laser alloyed layer with C-B-W-Cr powders on high-Ni-Cr infinite chilled cast iron roll was tempered at 500 °C for 60 mins and cooled to room temperature in the furnace. Optical scanning microscopy and X-ray diffractometer were used to investigate the microstructure and phases of the layer. A microhardness tester and wear tester were used to test the microhardness distribution, friction and wear behavior. Ferrite was formed in the tempered layer. Metastable carbides changed to stoichiometric carbides after tempering. FWHM (full width at half maximum) of the first primary peak was decreased by tempering. Microhardness decreased by 44%. Friction coefficient of the tempered layer exhibited gentle increase and a stable value of 0.6 was achieved for both the tempered layer and substrate. Relative wear resistance of the tempered layer was 1.11 times that of the tempered roll substrate. Mechanism of the effect of tempering on microstructure, FWHM, microhardness and wear properties were discussed.