摘要
为了获得高性能的镁合金电阻点焊接头,利用体视显微镜、扫面电镜等设备研究了点焊接头热影响区裂纹的形貌,并研究了裂纹的形成机理及控制方法。结果表明,热影响区裂纹属于液化裂纹,其出现在紧靠点焊熔核的热影响区,并且能够扩展到点焊接头的表面,它可能是由结晶裂纹在熔核边缘产生的应力集中引起的。液化裂纹的形成主要与低熔点液化膜(由低固溶度的原子扩散到熔化的晶界而形成)和冷却过程中产生的拉伸应力有关。应该选择相对低的热输入(即相对小的焊接电流、短的焊接时间或者高的电极压力)来降低热影响区液化裂纹敏感性。
In order to achieve magnesium ＇alloy resistance spot welding joint with high performance, study were made, by stereomicroscope and stereoscan,to pattern of crack in HAZ of resistance spot welding joint,also to mechanism and how to control.It is shown from result that HAZ crack belongs to liquation cracking,appears in HAZ just adjacent to weld nugget,can extend to surface of spot welding joint, and may be induced by solidification cracking at the edge of weld nugget.The formation of liquation cracking is mainly associated with low melting point liquid films from solute atoms of low solubility diffusing to the melted boundaries and tensile stress developed during cooling.It is favorable to select relatively low heat input（i.e, relatively low weld current,short welding time or high electrode force） for reducing the susceptibility of liquation cracking in HAZ.
出处
《电焊机》
北大核心
2009年第7期14-17,共4页
Electric Welding Machine
关键词
电阻点焊
镁合金
液化裂纹
resistance spot welding
magnesium alloy
liquation cracking
