Investigation and Application of Air-Hardening Bainitic Cast Steel Free from Molybdenum and Nickel

Air-hardening bainitic cast steel free from molybdenum and nickel was successfully developed whose main alloy elements were silicon,manganese,chromium and boron.Moreover,there were a few titanium,nitrogen,calcium and rare earth elements in the cast steel that could refine and purify the structure of steel.The effect of temper temperature on the structure and property of cast steel was also studied.The results show that the microstructure of the cast steel quenched at 920 ℃ and cooled by air is fine bainite.The toughness of cast steel increases when the temper temperature increase.The temper brittleness appears and the toughness decreases while tempering at 450 ℃.Since then,the toughness increases continuously while increasing the temper temperature.The hardness decreases along with the increase of temper temperature.The decrease of hardness is slow and it exceeds HRC55 when the temperature is lower than 300 ℃.The wear resistance decreases along with the increase of temper temperature under the condition of two-body pin-on-disc wear.In the condition of impact wear,cast steel tempering at 300 ℃ has excellent wear resistance.The liner,hammer and bucket tooth made of air-hardening bainitic cast steel free from molybdenum and nickel have good service effect,whose life-span is higher than that of high manganese steel by 100%~300%.