CAJ | 학술논문

采用蔡氏显微镜(OM)、拉伸力学性能测试、超声残余应力测试、透射电镜(TEM)、X射线衍射(XRD)以及差热分析实验(DSC)研究深冷前后车用 6005A合金焊接接头的显微组织和力学性能,揭示制约严寒地区铝合金车体材料规模化使用的技术问题.结果表明:3 次冷热循环深冷处理能促使焊接热影响区晶内的沉淀相均匀析出与弥散分布,其强化相平均尺寸由200 nm减小至50 nm.同时,焊缝区域粗大柱状晶低温"碎化"为超细等轴晶粒,产生大量的位错缠结,提升合金抗拉强度至234 MPa;加之冷热循环深冷处理可有效消除因焊接热输入而产生的大量残余应力,无相变深冷工艺能提高6005A铝合金焊接材料的结构稳定性.
채용채씨현미경(OM)、랍신역학성능측시、초성잔여응력측시、투사전경(TEM)、X사선연사(XRD)이급차열분석실험(DSC)연구심랭전후차용 6005A합금한접접두적현미조직화역학성능,게시제약엄한지구려합금차체재료규모화사용적기술문제.결과표명:3 차랭열순배심랭처리능촉사한접열영향구정내적침정상균균석출여미산분포,기강화상평균척촌유200 nm감소지50 nm.동시,한봉구역조대주상정저온"쇄화"위초세등축정립,산생대량적위착전결,제승합금항랍강도지234 MPa;가지랭열순배심랭처리가유효소제인한접열수입이산생적대량잔여응력,무상변심랭공예능제고6005A려합금한접재료적결구은정성.
The microstructural evolution and mechanical properties of welded joint of 6005A Al alloy for vehicle were studied by metallographic microscope, tensile test, residual stress measurement by ultrasonic method, transmission electron microscope, X-ray diffraction and differential scanning colourimeter, and some technical problems of the scale of application in aluminum alloys for car bodies were revealed. The results show the precipitated phase of welding heat affected zone can be dispersively distributed by three times cooling-thermal cycling treatment, and the average sizes of strengthening phase decreases from 200 nm to 50 nm. Meanwhile, the fragmentation mechanisms of transformation happen from dendritic crystal to ultra-fined equiaxed crystal during solidification at the welded joints of 6005A Al alloys, and a large number of dislocation twins form as well as its tensile strength is above 234 MPa. Besides, the cooling-thermal cycling treatment is effective to relieve the welding residual stress, the deep cryogenic treatment without phase-change can improve the dimensional stability of 6005A Al alloy welding materials.