微量硼对热轧低焊接裂纹敏感性钢力学性能的影响

Effect of Microelement Boron on Mechanical Properties of Low Welding Crack Susceptibility Steels

采用相同轧制工艺试制低焊接裂纹敏感性钢,对比分析了微量硼元素对显微组织和力学性能的影响。结果表明:含硼钢的屈服强度和抗拉强度比无硼钢分别要高150和105 MPa,但冲击韧性明显低于无硼钢。显微组织分析可知,硼的偏聚机制使组织中保留了明显的原始奥氏体晶界,并获得具有较大有效晶粒尺寸的板条贝氏体束,同时在贝氏体板条晶界上分布着一类长棒状含硼的碳化物析出相,这些因素均降低了含硼钢的冲击韧性。

Under the condition of the same rolling process for low welding crack susceptibility steels with boron bearing and boron free,the effect of microelement boron on the mechanical properties was investigated.The results present that the yield strength and tensile strength of boron bearing steel are 150 and 105MPa more than that of boron free steel,but the toughness is obviously inferior to boron free steel.The important factors of poor toughness of boron bearing steel by means of microstructure observation were that the boron segregation effect kept primitive austenite grain boundary,obtained lath bainite with large effective grain size and dispersed a kind of rod-like precipitates at the boundary of lath bainite.