超细晶Q460高强钢焊接接头组织与韧性研究

Investigation on Microstructure and Toughness of Ultrafine-grained Q460 High Strength Steel Welded Joint

采用手工焊条电弧焊和熔化极活性气体保护焊对超细晶Q460钢进行了焊接,分析表征了焊接接头的组织结构、显微硬度和冲击韧性的变化规律。研究结果表明,采用E5515焊条焊接,焊缝金属主要为先共析铁素体、多边形铁素体与少量珠光体。采用ER55-G焊丝,熔化极活性气体保护焊,焊缝金属主要由针状铁素体和少量多边形铁素体组成,焊丝中Ti元素的添加有利于获得针状铁素体组织。采用较小的焊接线能量,超细晶Q460钢热影响区粗晶区组织为粒状贝氏体组织。焊缝金属的显微硬度高于热影响区和母材的显微硬度,热影响区未出现软化现象。冲击试验表明,焊缝金属和热影响区均具有较高的冲击韧性,而且热影响区的韧性高于焊缝金属的韧性。

Shielded metal arc welding and gas metal arc welding were used to weld ultrafine-grained Q460 steel. The evolution of mierostructure, microhardness and impact toughness were analyzed. The results show that using E5515 electrode, weld metal consists of proeutectoid ferrite, idiomorphic ferrite and minor pearlite. Weld metal obtained by gas metal arc welding using ER55-G electrode rod is made up of acicular ferrite and idiomorphic ferrite with small amount. The addition of Ti is beneficial for obtaining acicular ferrite. When low heat input is employed, granular bainite presents in the coarse grained region in the heat affected zone. Microhardness of the weld metal is higher than that of the heat affected zone and base metal. Softening phenomena was not observed in the heat affected zone. Impact toughness test shows that both the weld metal and heat affected zone exhibit good impact toughness and the toughness of heat affected zone is superior to that of the weld metal.