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热处理对高强铝合金搅拌摩擦焊接头组织及力学性能的影响
李迎, 张玉芝, 张仲宝, 彭齐, 张国庆
首都航天机械有限公司, 北京 100076
摘要:
通过“搅拌摩擦焊+固溶+人工时效热处理”的方法实现了12 mm厚航天用高强铝合金2A14M的焊接及接头性能改善。研究表明未进行焊后热处理的焊接接头断裂位置位于焊核区,平均抗拉强度为192.3MPa,接头显微硬度呈“几”字形分布,硬度分布峰值位于焊缝区,接头不同特征区域的硬度差高达60。采取的焊后热处理对焊接接头及母材不仅具有细化晶粒、改善组织均匀性及优化强化相分布的作用,还能削弱拉伸过程中尖锐晶界对接头的撕裂作用,从而达到提高接头性能的目的,表现为:焊后热处理使接头内部显微硬度差为20,接头拉伸断裂于焊核区,抗拉强度达到440 MPa,为未进行焊后热处理接头的2.29倍;焊后固溶热处理的搅拌摩擦焊接头其断裂位置在焊核区及母材的几率大致相同,各占约50%,从而实现了提高搅拌摩擦焊接头性能的目标。
关键词:  2A14M铝合金  搅拌摩擦焊  焊后固溶  人工时效热处理
DOI:10.12044/j.issn.1007-2330.2018.06.009
分类号:TG407
基金项目:
Effect of Heat Treatment on Microstructure and Mechanical Properties of High-Strength Aluminum Alloy Friction Stir Welding Joints
LI Ying, ZHANG Yuzhi, ZHANG Zhongbao, PENG Qi, ZHANG Guoqing
Capital Aerospace Machinery Co., Ltd, Beijing 100076
Abstract:
A 12mm thickness 2A14M high-strengh aluminum alloy welding joint with improved mechanical performance was achieved by using the "friction stir welding + solidification + artificial aging heat treatment" procedure. The result show that tensile fracture occurs in the weld nugget zone of the welded joint without heat treatment.The average tensile strength is 192.3 MPa.The micro hardness distribution of the joint shows a π like shape with the peak area in the weld zone.The gap of hardness between different characteristic areas reach up to 60HRC.The presented post-weld heat treatment has refined the grains, improved the uniformity of the microstructure, optimized the distribution of the strengthening phase and weakened the tearing effects by the the sharp grain boundaries during tensile cracking process,thus significantly improved themechanical performances of the joint. As a result,the maximum hardness gap has been reduced to below 20HRC in the joint after the post-weld heat treatment.Moreover, tensile fracture may takes place in the base metal area or the weld seam with the tensile strength of up to 440 MPa which is 2.29 times of that of the joint without post-weld heat treatment. After post-welding heat treatment, probabilities of fracture appearance in base metal and weld nugget zone are same, both are 50%,and thus the goal of improving the performance of friction stir welded joints is achieved.
Key words:  2A14M aluminum alloy  Friction stir welding  Post-weld solid solution  Artificial aging heat treatment