特厚正火钢板的大线能量焊接性能

Extra-thick normalizingsteel plate research on welding performance of high wire energy

针对日钢营口中板120 mm厚度AH36大线能焊接用正火钢板,通过实际大热输入气电立焊和埋弧焊相结合的方法研究了焊接接头热影响区的显微组织和力学性能。结果表明,采用气电立焊双丝焊接,热输入为656.4 kJ/cm时,焊接接头的拉伸强度达到母材标准要求,但余量偏小。焊接接头的0℃KV_(2)韧性指标可达到对母材的标准要求,但1/2厚度位置冲击韧性值要低于表层。采用埋弧焊焊接,热输入为41.5~65.7 kJ/cm时,焊接接头的强韧性指标稳定达到母材标准要求。气电立焊焊接接头存在明显的粗晶区,其宽度在2 mm左右,距熔合线1200μm以内,过热奥氏体粗晶特征尤为明显,粗晶区的显微组织由晶界铁素体+针状铁素体+粒状贝氏体组成,Al-Ca-Si-Ti-Mg复合氧化物夹杂促进了针状铁素体形核。

Microstructure and mechanical properties of the heat affected zone(HAZ)of welded AH36normalizing steel plate that manufactured by Rizhao Steel Yingkou Medium Plate Co.,Ltd.,and the thickness is 120mm were studied by the combination of actual high heat input gas vertical welding and submerged arc welding.The results show that when the heat input is 656.4kJ/cm,the tensile strength of the welded joint meets the standard requirement of the base metal,but the margin is small.The 0℃KV_(2)toughness index of the welded joint can meet the standard requirements for the base material,but the impact toughness value at 1/2thickness is lower than that of the surface.When the submerged arc welding is used and the heat input is 41.5-65.7kJ/cm,the strength and toughness index of the welded joint can meet the standard requirements of the base material stably.There is an obvious coarse-grained zone in the welded joint with a width of about 2mm and a distance of less than 1200μm from the fusion line.The coarse-grained characteristics of superheated austenite are particularly obvious.The microstructure of the coarse-grained austenite consists of grain boundary ferrite+acicular ferrite+granular bainite,and the acicular ferrite core is promoted by the inclusion of Al-Ca-Si-Ti-Mg composite oxides.