热输入对Q890高强钢焊缝组织及性能的影响

针对国内某钢厂最新研制的Q890高强钢,采用三种不同的热输入对其进行气体保护焊接,研究了不同热输入对焊缝金属组织、硬度及冲击韧性的影响.结果表明,3种热输入下,焊缝组织主要以板条贝氏体为主,并含有粒状贝氏体、少量的板条马氏体和残余奥氏体.随着热输入的增大,焊缝组织中贝氏体铁素体板条粗化,板条马氏体逐渐减少,而粒状贝氏体逐渐增多,部分残余奥氏体由薄膜状向块状转变；焊缝金属硬度随着热输入的增大而下降；焊缝金属的冲击韧性亦呈逐渐下降的趋势.

Effect of heat input on microstructure and performance of weld metal for Q890 high strength steel

Welding tests were carried on the newly developed Q890 high strength steel with three different heat inputs, adopting gas shielded welding method. This paper mainly investigated the effect of different heat inputs on microstructure, hardness and impact toughness of weld metal. The results reveal that microstructure of weld metal mainly consists of lath bainite, as well as granular bainite, a small amount of lath martensite and retained austenite for three kinds of heat input. With the increasing of heat input, the lath of bainite ferritic in weld metal is coarsened, lath martensite decreases gradually, while the number of granular bainite increases, and topographies of retained austenite is changed from thin film to block. With the increasing of heat input, hardness of weld metal is reduced gradually. With the increasing of heat input, there seems to be a downward trend for impact toughness.