Study on microstructure and microhardness in surface layer of 20CrMnTi steel carburised at 880 degrees C with and without RE

This paper deals with the effect of adding rare earth (RE) in 880 degreesC drip-feed carburising atmosphere on the microstructure and microhardness pr ofiles in carburised layer, carbon potential and kinetics of weight gain of 20CrMnTi steel. The results show that the incorporation of RE increases th e carbon potential, flux of carbon and layer thickness. It is also found th at compared with 880 degreesC carburising, a good microstructure with a sup er fine martensite and less residual austenite were formed based on a lot o f dispersed granular carbide precipitates in the surface layer during RE ca rburising, which resulted in a remarkable increase in microhardness. (C) 20 01 Elsevier Science B.V. All rights reserved.