铝锂合金无针搅拌摩擦点焊接头组织演变与强化机制研究  

Microstructure Evolution and Strengthening Mechanism of the Probeless Friction Stir Spot Welding of a Al-Li Alloy

作　　者：褚强[1,2] 杨夏炜 李文亚[1] 范文龙[1] 邹阳帆 郝思洁 CHU Qiang;YANG Xiawei;LI Wenya;FAN Wenlong;ZOU Yangfan;HAO Sijie(School of Materials Science and Engineering,Northwestern Polytechnical University,Xi’an 710072;Xi’an Aerospace Engine Co.,Ltd.,Xi’an 710100)

机构地区：[1]西北工业大学材料学院,西安710072 [2]西安航天发动机有限公司,西安710100

出　　处：《机械工程学报》2024年第2期150-158,共9页Journal of Mechanical Engineering

基　　金：西北工业大学重点实验室开放课题(SKLSP202216);国家自然科学基金(52105402);陕西省自然科学基金(2021JQ-102)资助项目。

摘　　要：将2198铝锂合金无针搅拌摩擦点焊作为研究对象,围绕点焊接头微观组织与强化机制开展研究。结果表明,组织细化受连续动态再结晶、应变的几何效应和非连续动态再结晶的共同作用。其中,连续动态再结晶是主要的再结晶机制,同时伴随着剪切织构A/A({111}<110>),B/B({112}<110>),A_(1)*/A_(2)*({111}<112>)。焊接过程中析出相同样发生了显著变化,与母材晶体结构呈现半共格/非共格特征的T1相受焊接热循环影响发生粗化或固溶,搅拌区析出相几乎完全固溶,仅观察到少量弥散的与母材晶体共格的β'相,其强化效应明显减弱。无针搅拌摩擦点焊(Probeless friction stir spot welding,P-FSSW)接头非均匀组织特征导致其强化机制由析出强化和形变强化逐渐转变为细晶强化和固溶强化。The microstructure evolution and strengthening mechanism of probeless friction stir spot welded(P-FSSW)joints of 2198 Al-Li alloy are studied.The results show that the stir zone(SZ)is characterized by equiaxed grains,which is dominated by the continuous dynamic recrystallization,but the geometrical effect of imposed strain and limited discontinuous recrystallization are also involved.It is accompanied by shear textures,like A/A({111}<110>),B/B({112}<110>),A_(1)*/A_(2)*({111}<112>),which is attributed to the plastic flow induced by shear action.In addition,the primary strengthening phase of T1(Al2CuLi),which is semi-coherent/incoherent with the crystal structure of the base metal,is completely dissolved in the stir zone(SZ),but only a few of dispersedβ'phases are observed.The combined effect of extensive dissolution of the strengthening phases and reduction of dislocation density due to thermal cycle significantly decrease the hardness in the joint,while grain refinement and solution strengthening are considered as main factors affecting the SZ.

关 键 词：铝锂合金 搅拌摩擦点焊 微观组织 强化机制 

分 类 号：TG453[金属学及工艺—焊接]