二次正火温度对B+级钢低温韧性的影响

Effect of Second Normalizing Temperatures on Low-temperature Toughness of B+Grade Cast Steel

用金相显微镜、扫描电镜、低温冲击及拉伸试验等方法,研究了二次正火温度对B+级钢显微组织和低温冲击性能的影响。结果表明:较之一次正火,二次正火后组织明显细化,强度有所提高,塑性变化不大,低温冲击功明显提高,增加幅度为30%以上;二次正火温度不宜过高,否则将导致低温冲击功降低;亚温二次正火对提高低温冲击功作用不大;在870℃二次正火,可获得优良的强韧性配合。

The influences of the second normalizing temperatures on the microstructure and low temperature impact properties of B＋grade steel were studied by microscope,SEM,low temperature impact and tensile tests.The results indicate that,after the second normalizing,compared with the first normalizing,the microstructure is obviously refined,the strength increases to some extent,the ductility changes little,the low-temperature impact energy improves obviously,above 30%.The second normalizing temperature should not be too high,otherwise the low temperature impact energy decreases;the effect of the second normalizing on improving low-temperature impact energy is not obvious;the good matching between strength and toughness can be achieved after the second normalizing at 870 ℃.