摘要
以运载火箭助推器贮箱广泛应用的4 mm厚2219薄板铝合金为焊接对象,研制了浮动式双轴肩搅拌头,分析了内部塑性金属流动模式及特点,并推测出需匹配较低焊接热输入才能获得优质焊缝。工艺探索及优化试验结果直接验证了焊缝内部塑性金属流动模式及推测。接头宏观组织形貌分析结果显示:不同焊接速度下的焊缝横截面宏观形貌都可以观察洋葱环特征,且随着焊接速度提高,洋葱环特征越发增多,并从靠近前进侧的焊核区逐渐向后退侧孕育发展,这也有效验证了薄板铝合金双轴肩搅拌头的设计思路。薄板铝合金双轴肩搅拌摩擦焊接头横截面显微硬度分布均呈"U"型,接头显微硬度最低点位于焊核区与后退侧热机影响区的交界处。接头力学性能测试结果显示:随着焊接速度逐渐升高,接头抗拉强度逐渐升高,且当焊接速度达到350 mm/min时,接头抗拉强度达到最高值。铝合金浮动式双轴肩搅拌摩擦焊接头延伸率整体较高,焊接速度对其影响不大。铝合金双轴肩搅拌摩擦焊接头正、背弯均可以达到180°无裂纹。基于立式纵缝搅拌摩擦焊系统成功实现了2 m长试片的浮动式双轴肩搅拌摩擦焊,累计焊接长度达到60 m,且双轴肩搅拌头完整,未发现裂纹、扭曲或其他损伤。
The 2219 aluminum alloy with 4 mm thickness,which was used in the launch vehicle’s booster tank widely,was taken as the research object.The floating bobbin tool was developed,and the internal plastic metal flow pattern had been analyzed.The matching welding heat input of the weld seam with high quality could be obtained.The process exploration and optimization test results verified the plastic metal flow pattern inside the weld and the process speculation directly.The results of macroscopic morphology analysis of the joints show that the onion ring characteristics can be observed in the macroscopic morphology of the weld cross section at different welding speeds,and the onion ring characteristics increase with the welding speed increasing.This phenomenon validats the design idea of the bobbin use for the thin-plate aluminum alloy effectively.The microhardness distribution of the crosssection of FSWed thin plate aluminum alloy is U-shaped,and the lowest point of the microhardness of the joint is located at the junction of the weld nugget zone and the RS thermo-mechanical affected zone.The mechanical properties test results show that the tensile strength of the joint increased gradually with the welding speed increasing,and the tensile strength of the joint reach the highest value when the welding speed reachs 350 mm/mim.The floating bobbin FSWed aluminum alloy joints has a high elongation,and the welding speed has little effect on it.The floating bobbin FSWed joints can achieve 180°without cracks in both front and back bending tests.Based on the vertical longitudinal seam friction stir welding system,the floating bobbin friction stir welding of 2 m long test piece is realized successfully.The cumulative weld length reachs 60 m and the floating bobbin tool is intact with no cracks,distortion or other damage.
作者
郝云飞
侯明
韩忠帅
颜旭
蒋金龙
HAO Yunfei;HOU Ming;HAN Zhongshuai;YAN Xu;JIANG Jinlong(Capital Aerospace Machinery Company,Beijing 100076)
出处
《宇航材料工艺》
CAS
CSCD
北大核心
2020年第1期63-70,共8页
Aerospace Materials & Technology
基金
十三五装备预研共用技术课题资助项目(41423050128)。
关键词
2219薄板铝合金
浮动式双轴肩搅拌摩擦焊接
组织
性能
长试片验证
Thin sheet of 2219 aluminum alloy
Floating bobbin friction stir welding
Weld structure
Mechanical property
Long specimen
