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铝锂合金采用搅拌摩擦焊技术进行焊接可有效提高焊接接头的各项力学性能指标。采用SEM、TEM、EBSD等试验方法,对10mm厚1420铝锂合金搅拌摩擦焊焊接接头的显微组织形貌、织构类型、析出相以及接头硬度分布情况进行分析,讨论了组织结构对接头力学性能的影响。研究结果表明:焊接接头的焊核区、热机影响区以及热影响区呈现不同组织形貌;焊核区由均匀细小的再结晶组织构成,热机影响区板条组织发生弯曲变形,热影响区在焊接热循环作用下晶粒发生粗化,其组织形貌与母材基本保持一致;焊核区主要织构类型为变形织构S{123}<634>和再结晶织构R{124}<211>,含量分别为18.9%和18.1%,热机影响区和热影响区的主要织构类型与焊核区相同,含量稍有变化,母材中变形织构Copper{112}<111>为主要织构类型,体积分数为16.9%;合金的析出相为δ′相,即Al3Li,相的含量沿母材、热影响区、热机影响区方向递减,直至在焊核区内消失;焊缝的硬度值整体高于母材,并按照焊核区—热机影响区—热影响区—母材方向逐渐减少,焊接前进侧硬度始终小于后退侧硬度;试验中析出相对合金力学性能的影响较小,晶粒度是影响合金硬度的主要因素。
Al-Li alloy friction stir welding technology for welding can effectively improve the mechanical properties of welded joints indicators. SEM, TEM, EBSD and other test methods were used to analyze the microstructure, texture type, precipitated phase and joint hardness distribution of 10mm thick 1420 Al-Li alloy friction stir welded joints. The effects of microstructure on joint mechanics The impact of performance. The results show that the weld nugget zone, the heat affected zone and the heat affected zone show different microstructures. The weld nugget zone consists of uniform and fine recrystallized microstructure. The heat affected zone The grain morphology of the weld nugget is coarsening under the action of welding heat cycle, and the microstructure of the weld core is consistent with that of the base metal. The main texture types of weld nugget are S {123} <634> and recrystallized texture R {124} <634> 211> and their contents were 18.9% and 18.1% respectively. The main textural types in the heat-affected zone and the heat affected zone were the same as those in the nugget zone, and their content slightly changed. The deformed textures of the copper {112} <111> Texture type, volume fraction of 16.9%; alloy precipitation phase δ ’phase, that Al3Li, the phase content along the base metal, heat affected zone, the direction of heat affected zone decreases until the weld nugget disappears; weld The hardness value is higher than that of the base metal and decreases gradually according to the direction of nugget zone - heat affected zone - heat affected zone - base metal, and the hardness at the welding side is always less than the hardness at the back side. The influence of the mechanical properties of the alloy is small, Grain size is the main factor affecting the hardness of the alloy.