摘要
以搅拌头转速(n)和焊接速度(v)为变量,对6 mm厚7075-T6铝合金板材进行搅拌摩擦焊接试验,研究不同焊接参数下焊缝形貌、显微组织、力学性能的变化规律。结果表明,焊接速度100 mm/min时,n在600~1 400 r/min范围内焊缝均可成形;搅拌头转速800 r/min时,v在60~120 mm/min范围内焊缝均可成形。焊接接头BM是由再结晶组织和变形板条状组成的轧制组织,WNZ晶粒与强化相细小且分布均匀,形成典型“洋葱环”形貌,TMAZ在板条状组织内形成了回复晶粒组织,AS分界明显;WNZ、TMAZ晶粒大小与n呈正相关,与v呈负相关。接头硬度分布呈倒“M”形,焊缝区硬度较母材减小,最小值在RS侧TMAZ和HAZ过渡处,WNZ平均硬度分布随着n、v的增大呈先增大后降低的变化趋势;接头抗拉强度和伸长率,整体分布呈“镰刀”形,与n呈正相关,与v呈负相关。为获得焊缝成形良好、无明显缺陷,力学性能优良的焊接接头,需大的搅拌头转速配合小的焊接速度,n/v值应在10以上。
Friction stir welding(FSW)experiments were conducted on 6 mm thick 7075-T6 aluminum alloy plates,with the rotational speed(n)and welding speed(v)as variables,to investigate the effects of welding parameters on weld morphology,microstructure,and mechanical properties.The results indicate that sound welds can be achieved within a rotational speed range of 600-1400 r/min at a constant welding speed of 100 mm/min,and within a welding speed range of 60-120 mm/min at a constant rotational speed of 800 r/min.The base material(BM)exhibits a rolled structure comprising recrystallized grains and deformed elongated grains.In the weld nugget zone(WNZ),fine and uniformly distributed grains and strengthening phases form a typical“onion ring”structure.The thermo-mechanically affected zone(TMAZ)shows recovered grain structures within the elongated grains,with a distinct boundary on the advancing side(AS).The grain sizes in both the WNZ and TMAZ are positively correlated with the rotational speed(n)and negatively correlated with the welding speed(v).The microhardness profile across the joint exhibits a characteristic"inverted M"shape,with the weld zone being softer than the BM.The lowest hardness value is located at the transition between the TMAZ and the heat-affected zone(HAZ)on the retreating side(RS).The average hardness in the WNZ first increases and then decreases with increasing n and v.The tensile strength and elongation of the joints generally follow a"sickle-shaped"distribution trend,showing a positive correlation with n and a negative correlation with v.To produce defect-free joints with good formation and excellent mechanical properties,a higher rotational speed combined with a lower welding speed is recommended,with an n/v ratio preferably above 10.
作者
李志强
飞尚才
LI Zhiqiang;FEI Shangcai(Qinghai Higher Vocational&Technical Institute,Haidong 810799,China)
出处
《电焊机》
2026年第2期103-111,共9页
Electric Welding Machine
基金
青海高等职业技术学院科研项目经费资助(GZYKY202302)。
关键词
7075-T6
搅拌摩擦焊
宏观形貌
显微组织
力学性能
7075-T6 aluminum alloy
friction stir welding(FSW)
macro morphology
microstructure
mechanical properties
