Investigations on microstructures and properties of B containing cast steel for wear resistance applications

Abstract

The microstructures of B bearing cast steel (B steel) containing 0·8–1·2 wt-%B, 0·8–1·2 wt-%Cr, 1·0–1·5 wt-%Mn, 0·6–1·0 wt-%Si and 0·10–0·25 wt-%C have been characterised by means of optical microscopy, scanning electron microscopy, electron probe microanalyser and X-ray diffraction. The solidification structure of B steel consists of pearlite, ferrite, martensite and boride (Fe₂B), while the hardness is 1430–1480 HV. Borides distribute along the grain boundary in the form of eutectic. Fine lath martensite and eutectic Fe₂B can be obtained by water quenching at 1223–1273 K. The hardness and impact toughness of the B steel exceed 55 HRC and 150 kJ m⁻²respectively. The abrasion resistance determined using a pin abrasion tester is obviously higher than that of the martensitic cast steel and nears to the high chromium white cast iron.