焊接工艺对50CrVA弹簧钢焊接接头组织及性能的影响

采用ER50-6焊丝对50CrVA弹簧钢进行熔化极气体保护焊焊接试验，研究了不同焊接工艺对50CrVA弹簧钢焊接接头组织及性能的影响。结果表明，焊接电流为90 A、 100 A时，焊接接头组织主要由针状铁素体和先共析铁素体构成；焊接电流增大到110 A时，先共析铁素体消失。焊接电流为90 A时，焊接热影响区粗晶区主要由粗大的马氏体组织和带状组织构成；焊接电流为100 A时，高碳马氏体组织及带状组织消失，粗晶区组织由板条马氏体组织构成；焊接电流为110 A时，粗晶区马氏体组织长大，硬度显著下降。细晶区主要由细小的板条马氏体组织构成，不完全淬火区主要为马氏体、铁素体、贝氏体及索氏体构成的混合组织。随着焊接热输入的增大，50CrVA弹簧钢接头的抗拉强度和伸长率呈先上升后下降的趋势，断裂位置均在母材；焊接电流为90 A时，一个面弯试样出现断裂，其余均未出现裂纹；室温冲击功随焊接电流的增大逐渐增大，当焊接电流为110 A时，冲击功达到最大值35.67 J。

Effect of Welding Process on the Microstructure and Properties of 50CrVA Spring Steel Joint

The effects of different welding processes on the microstructure and properties of 50CrVA spring steel joints were studied by using ER50-6 welding wire. The results show that when the welding current is 90 A and 100 A, the microstructure of the welded joint is mainly composed of acicular ferrite and proeutectoid ferrite. When the welding current increases to 110 A, the proeutectoid ferrite disappears. When the welding current is 90 A, the coarse grained zone is mainly composed of coarse martensite and banded structure. When the welding current is 100 A, the high carbon martensite and banded structure disappear, and the coarse grained zone is composed of lath martensite. When the welding current is 110 A, the martensite structure in the coarse grain region grows up and the hardness decreases significantly. The fine grain zone is mainly composed of fine lath martensite, and the incomplete quenching zone is mainly composed of martensite, ferrite, bainite and sorbite. With the increase of welding heat input, the tensile strength and elongation of 50CrVA spring steel joint increases first and then decreases, and the fracture position is in the base metal. When the welding current is 90 A, a surface bending specimen fractures, and no cracks are found. The room temperature impact energy increases with the increase of welding current, and the maximum value is 35.67 J when the welding current is 110 A.