通过拉伸、冲击、弯曲、硬度和金相等试验对S355J2G3低合金钢MAG焊焊接接头的力学性能与显微组织进行了研究。结果表明: 采用G38 3 G3Si1焊丝对S355J2G3低合金钢进行焊接时, 可获得拉伸、弯曲和冲击性能均良好的焊接接头; 接头硬度的分布较均匀, 最高不大于380 HV; 焊缝组织为沿柱状晶晶界析出的块状先共析铁素体, 晶内为细小密集的针状铁素体和少量珠光体; 热影响区组织主要为先共析铁素体、针状铁素体、珠光体和少量的粒状贝氏体; 母材为均匀细小分布的铁素体和珠光体。

Mechanical properties and microstructure of S355J2G3 low-alloy steel MAG welded joints were studied through tensile test, bending test, impact test, hardness examination as well as microstructure analysis. The results showed that tensile, bending and impact properties of the welded joint were all good in case which was welded with G38 3 G3Si; and hardness of the welded joints distributed uniformly, while the highest value of hardness was below 380 HV. The microstructure of the weld seam contained block-shaped pro-eutectoid ferrite that located at the columnar grain boundaries, while fine and dense acicular ferrite and pearlite presented in the grains; the heat-affected zone mainly consisted of pro-eutectoid ferrite, acicular ferrite, pearlite, and a little granular bainite; the base metal contained fine ferrite and pearlite.