补焊工艺对30CrMnSiA接头微观组织及性能的影响研究

Research on the Influence of Repair Welding Process on Microstructure and Properties Around 30CrMnSiA Welded Joint

为了降低企业成本、避免检修过程中大型结构件直接更换造成的资源浪费,针对30CrMnSiA焊接件服役过程中出现的裂纹缺陷开展了补焊试验。试验过程中的焊缝填充金属分别选用HTJ-3、HTG-1焊条,并采用金相、扫描电镜、电子背散射衍射、拉伸、冲击、弯曲等试验对补焊前后接头的组织和性能进行表征分析,建立微观组织与力学性能之间的依存关系,为结构钢钢补焊工艺的优化提供一定的理论支撑。结果表明:补焊前后焊缝底部区域的组织均以马氏体+铁素体为主。补焊过程采用HTG-1作为填充金属,使得补焊区沿垂直于熔合线方向形成了粗大的柱状晶。另外,补焊前后接头原始焊缝区均以大角度晶界为主,使得该区域金属对裂纹扩展的阻碍能力增强。补焊后,焊接接头的抗拉强度及塑性指标都有明显的下降,但冲击韧性有所提高。

Repair welding experiment was carried out for cracks that produced in the service process around 30CrMnSiA welding parts,which purpose of this was to reduce the enterprises􀆳cost and avoid the waste of resources caused by the direct replacement of large structural parts in the maintenance process.The dependence relationship was established by comparison analysis with before and after repair welding around microstructure and properties that were characterized and analyzed with metallography,scanning electron microscopy(SEM),electron backscatter diffraction(EBSD),tensile,and impact and bending tests,which provided some theoretical support for the optimization of repair welding process around structural steel.Among them,HTJ⁃3 and HTG⁃1 electrodes were used to filling material during the test.The results showed that the martensitic and ferrite was found in the bottom welding layer before and after repair welding.And the coarse columnar crystals were formed along the direction perpendicular to the fusion line in the repair welding zone,which resulted from HTG⁃1 electrodes as the filler metal in repair welding process.In addition,the original welding zone of the joints before and after repair welding was dominated by high angle grain boundary,which can enhance the hindrance ability of metal in this area to crack propagation.Moreover,the tensile strength and plasticity indicator of the welded joints have been significantly declined after repairing welding,but the impact toughness has been improved.