稀土对B450NbRE钢热模拟组织的影响

Effects of Rare Earth Elements on Thermal Simulation Microstructure of B450NbRE Steel

工业生产中B450NbRE钢冲击韧性不稳定,分析原因在于轧制组织异常,而冶炼时存在稀土收得率不稳定现象,为了研究微量稀土对B450NbRE钢组织和相变的影响,使用真空感应炉冶炼了不同稀土质量分数(0.0010%,0.0046%和0.0160%)的B450NbRE钢,并采用Gleeble-1500热模拟实验机在950℃进行20%和40%的应变,通过对连续冷却过程膨胀数据的测量绘制CCT曲线,结合金相分析研究了稀土对B450NbRE钢组织和相变的影响作用。结果表明,冷却速率小于1℃.s-1时,B450NbRE钢组织以多边形铁素体和贝氏体为主,随着稀土含量的增加,铁素体含量先增加后降低,稀土具有促进多边形铁素体向针状铁素体转变的作用。

Studies of B450NbRE steels industrial production suggested that the abnormal microstructure after hot rolled caused the impact toughness of B450NbRE unstable,and it showed that the recovery of rare earth elements was unstable in steel making.The effect of rare earth elements on microstructure and phase transition of B450NbRE steels was discussed.Via vacuum induction furnace produced B450NbRE steels with different rare earth contents（0.0010%,0.0046% and 0.0160%）,the CCT curve were tested with Gleeble-1500 simulator at 950 ℃ and the strain degree was 20% and 40% respectively.Combined with the detection of microstructure,the effects of rare earth elements on transformation of B450NbRE steels were studied.The results indicated that the main microstructure of B450NbRE steels were ferrite and bainite at cooling rate less than 1 ℃·s-1,the content of ferrite first increased and then decreased with rare earth contents increasing.And it induced that the polygonal ferrite transformed to acicular ferrite with the increased rare earth elements contents.