铝合金CMT焊接性能的研究

发布时间：2018-06-25 06:08

本文选题：铝合金 + 冷金属过渡焊(CMT)　；参考：《沈阳工业大学》2017年硕士论文

【摘要】：由于铝及铝合金具有优异的性能,在多领域应用广泛,所以铝合金结构的高质量焊接具有重要的意义。铝合金常用的传统焊接方法有TIG焊及MIG焊等,这些焊接技术比较成熟。但是它们也存在各自的不足,如TIG焊生产效率较低、钨极承载电流能力差易造成焊缝金属夹钨,MIG焊存在裂纹、气孔、未熔合、未焊透及焊接变形等焊接缺陷。冷金属过渡焊(CMT焊)技术具有焊接热输入低,无飞溅等优点,适合铝合金焊接。但是CMT焊接技术是近几年面向市场,所以焊接工艺及焊接性能有待进一步研究。本文分别以2mm板厚的1060铝合金和6082-T6铝合金为试验材料,填充材料分别为直径1.2mm的ER1100纯铝焊丝和ER4043铝硅焊丝。通过优化工艺参数,确定了最佳工艺参数。利用金相显微镜(OM)、扫描电子显微镜(SEM)、能谱分析仪(EDS)和X射线衍射仪(XRD)对焊缝成形、显微组织、相组成进行了研究。利用显微维氏硬度计测量了焊接接头硬度分布;利用万能拉伸试验机测量焊接接头拉伸力学性能。试验结果表明,1060铝合金CMT焊接最佳工艺参数为焊接电流90A、焊接速度110cm/min、弧长修正系数0%。在最佳工艺参数下,焊缝成形美观。1060铝合金CMT焊缝金属组织主要由α-Al固溶体组成,结晶形态从熔合线到焊缝中心主要以柱状晶形态生长。焊缝金属硬度约为28-30HV,热影响区硬度约为27-32HV,母材金属硬度约为36-39HV。焊接接头抗拉强度约为64.45MPa,约是母材抗拉强度(87MPa)的70%,延伸率约为4.77%,断裂位置在热影响区,断口形貌表现为塑性断口。6082-T6铝合金CMT焊接最佳工艺参数为焊接电流105A、焊接速度110cm/min、弧长修正系数0%。在最佳工艺参数下,焊缝正面成形均匀,背面焊透,焊缝成形良好。6082-T6铝合金CMT焊缝金属组织主要由α-Al固溶体和少量Mg2Si金属间化合物组成,α-Al固溶体的结晶形态由熔合线到焊缝中心依次由胞状晶、柱状晶及等轴晶组成。焊缝金属硬度约为65-73HV,热影响区硬度约为60-95HV,母材金属硬度约为95-98HV。焊接接头抗拉强度约为188.52MPa,约是母材抗拉强度(310.24MPa)的61%,延伸率约为3.09%,断裂位置在热影响区,拉伸断口形貌表现为塑形断口。
[Abstract]:Because aluminum and aluminum alloys have excellent properties and are widely used in many fields, high quality welding of aluminum alloy structures is of great significance. TIG welding and MIG welding are common traditional welding methods for aluminum alloy. However, they also have their own shortcomings, such as low production efficiency of TIG welding and poor bearing current capacity of tungsten electrode, which can easily lead to welding defects such as cracks, porosity, non-fusion, failure to weld penetration and welding deformation in weld metal intercalated tungsten MIG welding. Cold metal transfer welding (CMT) technology has the advantages of low heat input and no spatter, so it is suitable for aluminum alloy welding. However, CMT welding technology is market-oriented in recent years, so welding process and welding performance need further study. In this paper, 1060 aluminum alloy and 6082-T6 aluminum alloy with thickness of 2mm plate were used as experimental materials, and the filling materials were ER1100 pure aluminum wire with diameter 1.2mm and ER4043 Al-Si wire with diameter respectively. The optimum process parameters are determined by optimizing the process parameters. Metallographic microscope (OM), scanning electron microscope (SEM), energy dispersive analyzer (EDS) and X-ray diffraction (XRD) were used to study the formation, microstructure and phase composition of the weld. Hardness distribution of welded joints was measured by microhardness tester and tensile mechanical properties of welded joints were measured by universal tensile testing machine. The experimental results show that the optimum welding parameters for CMT of 1060 aluminum alloy are welding current 90A, welding speed 110 cm / min, arc length correction coefficient 0. Under the optimum process parameters, the microstructure of CMT weld metal formed by beautiful. 1060 aluminum alloy is mainly composed of 伪 -Al solid solution, and the crystal morphology mainly grows in columnar form from the fusion line to the center of the weld. The hardness of weld metal is about 28-30HV. the hardness of heat-affected zone is about 27-32HV. the hardness of base metal is about 36-39HV. The tensile strength of the welded joint is about 64.45 MPA, which is about 70 of the base material tensile strength (87MPa), and the elongation is about 4.777.The fracture position is in the heat-affected zone. The fracture morphology is: plastic fracture. 6082-T6 aluminum alloy CMT welding parameters: welding current 105A, welding speed 110 cm / min, arc length correction coefficient 0. Under the optimum process parameters, the weld face is formed evenly, and the back side is fully welded. The microstructure of CMT weld metal is mainly composed of 伪 -Al solid solution and a small amount of mg _ 2Si intermetallic compound. The crystal morphology of 伪 -Al solid solution is composed of cellular crystal, columnar crystal and equiaxed crystal from fusion line to weld center. The hardness of weld metal is about 65-73HV. the hardness of heat-affected zone is about 60-95HV. the hardness of base metal is about 95-98HV. The tensile strength of the welded joint is about 188.52 MPa, which is about 61% of the base material tensile strength (310.24 MPA), and the elongation is about 3.09. The fracture position is in the heat-affected zone, and the tensile fracture appearance is shaped fracture.
【学位授予单位】：沈阳工业大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TG457.14

【参考文献】