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为了改善超高强度钢40CrNi2Si2MoVA的焊接性能,采用CO2激光对其进行了焊接处理。利用光学显微镜、显微硬度仪、电子万能试验机、电子扫描显微镜和X射线应力测定仪等对焊接接头的显微组织、硬度、拉伸强度、拉伸断口和残余应力进行了研究。结果表明,焊缝中心区组织为等轴晶,近中心区为小柱状晶,边缘区为柱状树枝晶与粗大柱状晶,熔合区为柱状晶、胞状晶。热影响区(HAZ)主要组织为板条马氏体、岛状马氏体、贝氏体及少量残余奥氏体;焊缝区平均硬度595HV,硬度最大值在HAZ,其值为637HV;从HAZ到基材硬度值下降显著;接头拉伸断裂部位发生在靠近焊缝基材区,拉伸断口为韧窝断口,其抗拉强度值和母材拉伸强度值相当,平均值为1607.8MPa,接头冲击韧度为54.5J/cm2;从焊缝中心区到基材区,焊接残余应力先增大,后减小,变化显著。
In order to improve the welding performance of ultra high strength steel 40CrNi2Si2MoVA, CO2 laser was used to weld it. The microstructure, hardness, tensile strength, tensile fracture and residual stress of welded joints were studied by using optical microscope, microhardness tester, electronic universal testing machine, electronic scanning microscope and X-ray stress analyzer. The results show that the central zone of weld is equiaxed, the near center is small columnar, and the marginal zone is column dendrite and coarse columnar. The fusion zone is columnar and cellular. Heat affected zone (HAZ) mainly lath martensite, island martensite, bainite and a small amount of retained austenite; weld zone average hardness of 595HV, the maximum hardness in the HAZ, the value of 637HV; from HAZ to the substrate hardness decreased significantly; joint tensile fracture occurred near the base area of the weld, the tensile fracture is dimple fracture, the tensile strength value and the tensile strength of the parent material value is equivalent to an average of 1607.8MPa , The impact toughness of the joint is 54.5J / cm2; from the weld center area to the substrate area, the welding residual stress first increases, then decreases, the change is remarkable.