超声振动辅助铝/钢电阻点焊接头形成机理研究  

Exploring the Formation Mechanism of Aluminum/Steel Resistance Spot Welding Joint Assisted by Ultrasonic Vibration

作　　者：任宝凯 周亢 王刚 Ren Baokai;Zhou Kang;Wang Gang(School of Mechatronical Engineering,Beijing Institute of Technology,Beijing 100081)

机构地区：[1]北京理工大学机电学院,北京100081

出　　处：《机械工程学报》2024年第22期139-152,共14页Journal of Mechanical Engineering

基　　金：国家自然科学基金资助项目(51605103)。

摘　　要：为了提高铝/钢点焊接头的质量,将超声纵向振动作为辅助工艺引入常规电阻点焊过程中。通过接头显微结构分析和焊接过程能量分析,并结合有限元数值计算的结果,确定了超声振动辅助铝/钢电阻点焊熔核形成机理。在此基础上,对超声振动辅助电阻点焊过程中铝/钢接头的界面化合物、焊接缺陷、显微硬度和接头强度特性进行综合分析。结果表明,引入超声纵向振动后,铝/钢双熔核尺寸明显减小,这是多种超声效应共同作用的结果,具体来说,超声波振动降低了板材之间的接触电阻,同时在声空化和声流效应的作用下,熔融态钢的电导率以及熔融态铝的热导率增加。此外,超声振动可以增加钢板向铝板侧的隆起高度,同时促进熔融铝和近熔铝的径向蠕变,拓展了铝/钢之间的有效接合面积。超声振动还有效地降低界面化合物层的厚度,抑制界面焊接缺陷的形成。拉剪试验结果表明,超声纵向振动可实现铝/钢接头的铝侧纽扣拉出失效模式,其峰值拉剪载荷相较于常规电阻点焊(Resistance spot welding,RSW)工艺提高了48.68%。In order to improve the quality of aluminum/steel spot welded joints,ultrasonic longitudinal vibration is introduced into the conventional resistance spot welding(RSW)process.Considering joint microstructure analysis,welding process energy analysis,and the results of finite element numerical calculations,the nugget formation mechanism of ultrasonic vibration-assisted resistance spot welding(UA-RSW)of aluminum/steel welded joint is determined.Subsequently,a comprehensive analysis of interfacial compounds,welding defects,microhardness,and joint strength characteristics during UA-RSW of aluminum/steel joints is conducted.The results demonstrate a significant reduction in the sizes of the aluminum/steel double nugget after the introduction of ultrasonic vibration.This reduction is a result of competing of multiple ultrasonic effects,where ultrasonic vibrations reduce the contact resistance between sheets.Additionally,the electrical of molten steel and thermal conductivities of molten aluminum increase due to acoustic cavitation and acoustic flow effects.Moreover,ultrasonic vibration increases the bulge height of the steel sheet,promotes the radial creep of molten aluminum and near-molten aluminum,expanding the effective bonding area between aluminum and steel sheets.Ultrasonic vibration also effectively reduces the thickness of the intermetallic compound(IMC)layer to less than 3.0μm in thickness and inhibits the formation of interface welding defects.Tensile-shear tests demonstrate that ultrasonic longitudinal vibration can achieve an aluminum button pull-out failure mode,increasing its peak tensile-shear load by 48.68%compared with the conventional RSW process.

关 键 词：超声振动 电阻点焊 铝/钢 微观结构 双熔核演变 

分 类 号：TG457[金属学及工艺—焊接]