工程科学学报，第38卷，第7期：979985,2016年7月 Chinese Journal of Engineering,Vol.38,No.7:979-985,July 2016 DOI:10.13374/j.issn2095-9389.2016.07.013:http://journals.ustb.edu.cn 焊接电流对镁/镀锌钢TG熔一钎焊接头显微组织与 力学性能的影响 洪 淼，袁新建区，梁雪波 重庆大学材料科学与工程学院，重庆400045 ☒通信作者，E-mail:xinjianyuan@cu.cdu.cn 摘要采用TG熔一钎焊焊接方法，以镁合金焊丝为填充材料，对镁合金与镀锌钢进行连接实验，并分析热输入量对接头显 微组织和力学性能的影响.热输入量过小会阻碍镁/钢界面反应层的形成而使得焊缝难以焊合，热输入量过大又会促进焊缝 内部脆性第二相的长大，降低接头力学性能.接头强度随着焊接电流和焊接速度的增大都呈现先上升后下降的趋势，电流为 70A时强度达到最大，该值接近AZ31B母材的88.7%.此时断裂发生于焊缝熔焊区，断面出现大量韧窝和撕裂棱，呈现出塑 性断裂特征 关键词镁合金：钢：TG熔焊；钎焊；显微组织：力学性能 分类号TC457 Effect of heat input on the microstructure and mechanical properties of TIG welded-brazed magnesium/steel joints HONG Miao,YUAN Xin-jian,LINAG Xue-bo College of Materials Science and Engineering,Chongqing University,Chongqing 400045,China Corresponding author,E-mail:xinjianyuan@cqu.edu.cn ABSTRACT A tungsten inert gas (TIG)welding-brazing technology using an Mg-based filler was developed for joining Mg alloys to steel.The effects of heat input on the microstructure and mechanical properties of Mg/steel joints were investigated.The results indi- cate that the joining strength of the joints is poor with low heat input,owing to insufficient metallurgical reaction between the Mg alloy and steel.But with excessive heat input,the growth of the brittle second phase in the seam occurs,resulting in the decrease of me- chanical properties.The joining strength of the joints increases first and then decreases with the increase of welding current and weld- ing speed.An acceptable joint is obtained with a welding current of 70 A,representing 88.7%joint efficiency relative to AZ31B base material.With this parameter,fracture occurs at the fusion zone and the fracture surface is characterized by equiaxed dimple patterns accompanied with lamellar tearing.The fracture surface embodies the characteristics of plastic fracture. KEY WORDS magnesium alloys:steel:TIG welding:brazing;microstructure:mechanical properties 金属镁及其合金是最轻的金属结构材料，其密度为异质金属连接的热点问题，实现镁/钢异质金属的高 仅为1.74gcm3,且比强度高，尺寸稳定，导热导电性 效连接具有重大工程意义四.但是，由于镁和钢之间 好，易于加工成形m,因而被广泛应用于航空航天、军巨大的物理化学性质差异，如熔点差异大、共熔性小且 工产业等领域.钢因其良好的力学性能可满足不同的 治金不相熔，使得传统的熔焊方法难以实现其可靠 生产要求而成为工业生产中使用最广泛结构材料.作 连接回. 收稿日期：2015-07-10 基金项目：国家自然科学基金资助项目(51205428)：中央高校基本科研业务费资助项目(CDJZR13130040,CDJZR12130047)工程科学学报，第 38 卷，第 7 期: 979--985，2016 年 7 月 Chinese Journal of Engineering，Vol． 38，No． 7: 979--985，July 2016 DOI: 10． 13374 /j． issn2095--9389． 2016． 07． 013; http: / /journals． ustb． edu． cn 焊接电流对镁 /镀锌钢 TIG 熔--钎焊接头显微组织与 力学性能的影响 洪 淼，袁新建，梁雪波 重庆大学材料科学与工程学院，重庆 400045  通信作者，E-mail: xinjianyuan@ cqu． edu． cn 摘 要 采用 TIG 熔--钎焊焊接方法，以镁合金焊丝为填充材料，对镁合金与镀锌钢进行连接实验，并分析热输入量对接头显 微组织和力学性能的影响． 热输入量过小会阻碍镁/钢界面反应层的形成而使得焊缝难以焊合，热输入量过大又会促进焊缝 内部脆性第二相的长大，降低接头力学性能． 接头强度随着焊接电流和焊接速度的增大都呈现先上升后下降的趋势，电流为 70 A 时强度达到最大，该值接近 AZ31B 母材的 88. 7% ． 此时断裂发生于焊缝熔焊区，断面出现大量韧窝和撕裂棱，呈现出塑 性断裂特征． 关键词 镁合金; 钢; TIG 熔焊; 钎焊; 显微组织; 力学性能 分类号 TG457 Effect of heat input on the microstructure and mechanical properties of TIG welded--brazed magnesium / steel joints HONG Miao，YUAN Xin-jian ，LINAG Xue-bo College of Materials Science and Engineering，Chongqing University，Chongqing 400045，China  Corresponding author，E-mail: xinjianyuan@ cqu． edu． cn ABSTＲACT A tungsten inert gas ( TIG) welding--brazing technology using an Mg-based filler was developed for joining Mg alloys to steel． The effects of heat input on the microstructure and mechanical properties of Mg / steel joints were investigated． The results indi￾cate that the joining strength of the joints is poor with low heat input，owing to insufficient metallurgical reaction between the Mg alloy and steel． But with excessive heat input，the growth of the brittle second phase in the seam occurs，resulting in the decrease of me￾chanical properties． The joining strength of the joints increases first and then decreases with the increase of welding current and weld￾ing speed． An acceptable joint is obtained with a welding current of 70 A，representing 88. 7% joint efficiency relative to AZ31B base material． With this parameter，fracture occurs at the fusion zone and the fracture surface is characterized by equiaxed dimple patterns accompanied with lamellar tearing． The fracture surface embodies the characteristics of plastic fracture． KEY WOＲDS magnesium alloys; steel; TIG welding; brazing; microstructure; mechanical properties 收稿日期: 2015--07--10 基金项目: 国家自然科学基金资助项目( 51205428) ; 中央高校基本科研业务费资助项目( CDJZＲ13130040，CDJZＲ12130047) 金属镁及其合金是最轻的金属结构材料，其密度 仅为 1. 74 g·cm － 3，且比强度高，尺寸稳定，导热导电性 好，易于加工成形［1］，因而被广泛应用于航空航天、军 工产业等领域． 钢因其良好的力学性能可满足不同的 生产要求而成为工业生产中使用最广泛结构材料． 作 为异质金属连接的热点问题，实现镁/钢异质金属的高 效连接具有重大工程意义［2］． 但是，由于镁和钢之间 巨大的物理化学性质差异，如熔点差异大、共熔性小且 冶金不相熔，使得传统的熔焊方法难以实现其可靠 连接［3］．