热输入对E36钢SAW焊缝组织及韧性的影响

Effects of large heat input on microstructure and toughness of E36 steel weld metals with submerged arc welding

为提高建造海洋采油平台的效率、减少生产周期,进而为实际生产提供数据支持,采用3种不同热输入对海洋采油平台用E36钢进行埋弧焊焊接,通过光学显微镜(OM)、透射电镜(TEM)、扫描电镜(SEM)和电子背散射衍射技术(EBSD)对焊缝微观组织及夹杂物形貌进行了观察,研究了不同热输入对焊缝组织及韧性的影响,并分析了不同热输入对焊缝夹杂物尺寸分布和成分的影响.结果表明:热输入为50 k J/cm时,焊缝金属韧性较好;随着焊接热输入的增加,焊缝的冲击韧性降低,但仍能满足性能指标,焊缝金属中夹杂物成分相差较大,有效夹杂物数量减少,焊缝金属中大角度晶界比例减少;对于E36钢,热输入为160 k J/cm时不仅能使韧性符合要求还能提高生产效率.

E36 steel for offshore drilling platform was welded with submerged arc welding （SAW） in three different heat inputs, aiming to improve the efficiency of constructing offshore drilling platform and to reduce production cycle, and thus to provide data support for practical production. The mierostructures of weld metals and the morphology of inclusions were analyzed by means of OM, TEM, SEM and EBSD. The effects of heat input on the microstructure and impact toughness of the weld metals and the size, distribution, compositions of inclusions were investigated. The results show that the impact toughness of weld metal is the best with heat input of 50 kJ/cm. With the increase of welding heat input, the impact toughness of weld metals decreases yet it still can satisfy the performance index, and the compositions of inclusions in weld metal vary widely, and the number of valid inclusions reduce, the proportion of large angle grain boundary in weld metal reduce. When the heat input is 160 kJ/cm, the welding process not only can make toughness meet the requirement also can improve the production efficiency.