Ni元素对高碳纳米结构贝氏体钢组织和性能的影响

Effects of Ni on microstructures and properties of high carbon nano-structured bainite steels

设计了含Ni和无Ni两种纳米结构贝氏体钢种,进行了不同温度下等温淬火热处理实验,目的是研究Ni对等温淬火纳米结构贝氏体钢相变、组织和性能的影响。结果表明,与连续冷却工艺不同,在等温淬火过程中,Ni元素的添加降低了贝氏体相变驱动力,减少贝氏体体积分数,同时使TTT曲线右移,减慢等温贝氏体相变动力学。此外,在等温淬火后,Ni元素的添加提高钢的冲击性能,但由于贝氏体量的减少和残余奥氏体的增多,使钢的拉伸性能降低。其次,随着相变温度的升高,含Ni钢和无Ni钢的强塑积略有增加。

Two bainite steels with and without Ni were designed and austempering treatments at different temperatures were conducted.The purpose is to study the effects of Ni on the transformation behavior,microstructure and properties of austempered nano-structured bainite steels.The results show that Ni addition decreases the bainite transformation driving force during austempering treatment,and consequently decreases the bainite amount.Besides,Ni addition moves the TTT curve towards right and decreases the transformation kinetics of isothermal bainite transformation.This is different from the effect of Ni during continuous cooling.In addition,Ni addition increases the impact property after austempering treatment,but the tensile property decreases with Ni addition due to the decrease in bainite amount and the increase in retained austenite amount.Moreover,the product of strength and elongation increases slightly with the increase in transformation temperature in both Ni free and Ni added steels.