碳纤维增强热塑性复合材料与高强钢的电阻单元焊

Resistance Element Welding of Carbon Fiber Reinforced Thermoplastic Composites tOHigh-Strength Steel

利用电阻单元焊(REW)实现了碳纤维增强尼龙6复合材料(CF/PA6)与TWIP980钢的高强度连接.使用304不锈钢铆钉作为辅助单元,研究了焊接电流与焊接时间对接头力学性能的影响.得到强度不同的4种失效模式,分析了接头的微观组织以及CF/PA6与铆钉和钢板界面微观形貌.CF/PA6具有远低于高强钢的熔点和热导率,使得CF/PA6在焊接中极易发生过热分解.在保证形成一定尺寸熔核的同时,避免或减少CF/PA6的分解是CF/PA6高强钢电阻单元焊能够成功实施的关键.通过采用大焊接电流、短焊接时间这种较“硬”的焊接工艺,可以在获得较高强度接头的同时,降低CF/PA6的分解.基于接头失效载荷,确定了本研究条件下的焊接工艺窗口.该工艺对焊接时间的变化敏感,许用的焊接时间窗口窄.在焊接工艺窗口内,仍无法完全避免CF/PA6的分解.有必要对焊接过程温度场和熔核形成机理等开展进一步研究.

The high strength joining of carbon fiber reinforced nylon 6 composites(CF/PA6)tOTWIP980 steel was achieved by resistance element welding(REW).A 304 stainless steel rivet was used as an assistant element.The effect of welding current and welding time on the joint mechanical property was studied.Four joint failure modes with different strengths were identified,and the microstructures of joints,and the interfaces between CF/PA6 and the steel were analyzed.As the melting point and thermal conductivity of CF/PA6 are lower than those of the high-strength steel,it is prone tOoverheat and decompose during welding.While ensuring the formation of a certain size of weld nugget,avoiding or reducing the decomposition of CF/PA6 is the key tOthe successful implementation of CF/PA6 high-strength steel REW.By using a hard welding process such as high welding current and short welding time,high strength joints can be obtained while reducing the decomposition of CF/PA6.Based on the failure load of the joint,the weld lobe under the conditions of this study was determined.The process is sensitive tOthe change of welding time,and the allowable welding time range is narrow.The decomposition of CF/PA6 cannot be avoided completely even when the welding parameters in the weld lobe are employed.Therefore,it is necessary tOconduct further research on the temperature field and the nugget formation mechanism of the REW process.