焊接电流对AZ31B镁合金MIG焊接接头组织与性能的影响  

Effect of welding current on microstructure and properties of AZ31 B magnesium alloy MIG welded joint

作　　者：金煜庭 林光磊 林茂春 纪联珍 张富辉 JIN Yu-ting;LIN Guang-lei;LIN Mao-chun;JI Lian-zhen;ZHANG Fu-hui(School of Materials Science and Engineering,Fujian University of Technology,Fuzhou 350118,China;Fujian Key Laboratory of New Material Preparation and Forming Technology,Fuzhou 350118,China;Fujian Kunfu Co.,Ltd.,Longyan 364302,China)

机构地区：[1]福建工程学院材料科学与工程学院,福建福州350118 [2]福建省新材料制备与成形技术重点实验室,福建福州350118 [3]福建坤孚股份有限公司,福建龙岩364302

出　　处：《轻合金加工技术》2020年第8期54-60,共7页Light Alloy Fabrication Technology

基　　金：福建省高校产学合作项目(2019H6021)。

摘　　要：针对在轻量化结构件中应用广泛的AZ31B镁合金,研究了熔化极氩弧焊(MIG)焊接过程中焊接电流对焊件组织、性能的影响,以及与其连接可靠性的对应关系。通过显微维氏硬度计、万能拉伸试验机、金相显微镜、扫描电镜等检测结果表明:焊接电流介于70 A^100 A范围内,随着焊接电流增加,其焊缝熔宽增加不明显,焊缝处的余高呈降低趋势,有利于焊丝与母材之间的相互融合连接,提高焊件的连接可靠性。采用AZ61A镁合金焊丝使焊接熔化后的焊缝区域晶粒内部拥有更多β-Mg17Al12强化相,明显提高了焊缝区强度和硬度,有利于增强其焊接头的连接可靠性。其中焊接电流80 A的焊件接头综合性能最好,其抗拉强度达到227.5 N/mm2,焊后抗拉强度损失小,可满足GB/T 5156对其抗拉强度的规定要求,其伸长率也是最高的(达5.5%),但与母材相比损失仍较明显。因此,对塑性要求不高的非刚性碰撞类镁合金构件之间的连接可采用MIG焊接,能够确保其连接强度足够的前提下,有效提高其连接工序效率。Aiming at AZ31 B magnesium alloy,which is widely used in lightweight structural parts,the influence of welding current on the structure and properties of weldment during fusion arc welding(MIG)was studied,and the corresponding relationship with its connection reliability.The micro Vickers hardness tester,universal tensile tester,metallographic microscope,scanning electron microscope and other testing results show that the welding current is in the range of 70 A-100 A.As the welding current increases,the increase of the weld width is not obvious.The residual height at the weld seam is reduced in a trend,which is conducive to the fusion and connection between the welding wire and the base material,and improves the connection reliability of the weldment.The use of AZ61A magnesium alloy welding wire makes more p-Mg17Al12 strengthening phase inside the grain of the welded area after welding,which significantly improves strength and hardness of the welded area and is conducive to enhancing the connection reliability of its welding head.Among them,the welding joint with the welding current of 80 A has the best comprehensive performance.Its tensile strength reaches 227.5 N/mm2,and the loss of tensile strength after welding is small.It can meet the requirements of GB/T 5156 for its tensile strength,and the elongation is highest,up to 5.5%,but the loss is still significant compared to the base material.Therefore,MIG welding can be used for the connection between non-rigid collision magnesium alloy members with low plasticity requirements,which can effectively improve the efficiency of the connection process on the premise of ensuring the sufficient connection strength.

关 键 词：AZ31B镁合金 熔化极氩弧焊 焊接电流 焊缝区域微观组织 焊后抗拉强度 

分 类 号：TB331[一般工业技术—材料科学与工程]