硼对低焊接裂纹敏感性高强钢组织性能的影响

 分析了在控轧、控轧加回火、调质等不同工艺条件下，硼对低焊接裂纹敏感性钢显微组织和力学性能的影响。结果表明，硼抑制先共析铁素体形成，提高淬透性，在控轧工艺下含硼钢形成粗大的贝氏体和马氏体组织，并保留了原始奥氏体晶界；调质工艺得到回火索氏体组织，但含硼钢的大角度晶界比例与无硼钢相比较低。硼在强度上的作用显著，上述3种工艺下含硼钢的抗拉强度分别比无硼钢高300, 214, 101MPa，屈服强度分别高320，259，144MPa，但伸长率和冲击韧性均有所降低。无硼钢在调质工艺下、含硼钢在控轧加回火工艺下具有较好的强韧性匹配。

Effect of Boron on the Microstructure and Properties of High Strength Steels With Low Susceptibility to Weld Cracking

The effect of boron on the microstructure and mechanical properties of high strength steels with low welding crack sensitivity, in the conditions of TMCP, TMCP+T and QT, respectively, were investigated. The result shows that boron improves the hardenability by suppressing the formation of proeutectoid ferrite. The microstructure of the boron-bearing steel, in the state of TMCP, consists of coarse bainite and martensite, and the prior austenite grain boundaries are retained. The QT process leads to a microstructure of tempered sorbite, but the boron-bearing steel exhibits lower fraction of high angle grain boundaries than the boron-free steel. A significant increase in strength, namely tensile strength by 300, 214 and 101MPa and yield strength by 320, 259 and 144MPa, respectively, for the above mentioned three conditions, but decrease in elongation and impact toughness, by the addition of boron, is observed. The best combination of strength and toughness is found to be achieved by QT process for the boron-free steel and TMCP+T process for the boron-bearing steel.