(1. 天津大學(xué) 材料科學(xué)與工程學(xué)院，天津 300354；
2. 上海航天設(shè)備制造總廠，上海 200245)
摘 要: 對12 mm厚板2195-T8鋁鋰合金進(jìn)行靜止軸肩攪拌摩擦焊(Stationary shoulder friction stir welding, SSFSW)工藝試驗，探討工藝參數(shù)對接頭組織非均質(zhì)性和力學(xué)性能的影響。結(jié)果表明：轉(zhuǎn)速在300~500 r/min及焊接速度在30~80 mm/min范圍內(nèi)可獲得表面光滑、無缺陷的焊縫。轉(zhuǎn)速為300 r/min時，焊核區(qū)(Welding nugget zone, WNZ)呈梯形截面且沿厚度分布比較均勻；轉(zhuǎn)速為400~500 r/min時，WNZ形狀明顯不規(guī)則并在焊縫表面附近形成異常流動的回填區(qū)，WNZ沿厚度方向的晶粒尺寸相差2~3倍；轉(zhuǎn)速降低為300 r/min時，晶粒尺寸差別明顯減小。轉(zhuǎn)速為300 r/min時，WNZ硬度沿厚度方向分布均勻；轉(zhuǎn)速為400~500 r/min時，WNZ底部硬度值遠(yuǎn)小于中間和頂部。在轉(zhuǎn)速為300 r/min及焊接速度為80 mm/min的優(yōu)化工藝條件下，WNZ抗拉強(qiáng)度可達(dá)到母材的71.57%。拉伸試樣的斷裂位置發(fā)生在熱力影響區(qū)和熱影響區(qū)交界處或WNZ底部，具有典型的塑性斷裂特征。
關(guān)鍵字: 厚板鋁鋰合金；靜止軸肩攪拌摩擦焊；非均質(zhì)性；力學(xué)性能
（1. School of Materials Science and Engineering, Tianjin University, Tianjin 300354, China;
2. Shanghai Aerospace Equipment Manufacturer Co., Ltd., Shanghai 200245, China）
Abstract:The stationary shoulder friction stir welding (SSFSW) process tests were carried out on 12-mm-thick 2195-T8 Al-Li alloy plates, and the effects of welding process parameters on the microstructure heterogeneity and mechanical properties of the joints were discussed. The results show that smooth weld surface and completely dense defect-free weld can be obtained when the spindle speed is 300-500 r/min and the welding speed is 30-80 mm/min. When the rotating speed is 300 r/min, the welding nugget zone (WNZ) is trapezoidal, and the section is homogeneously distributed along the thickness direction. At 400-500 r/min, the shape of WNZ is obviously irregular, and refill zone (RZ) with abnormal flow is formed near the weld surface. The grain size difference along the thickness direction is 2-3 times at 400-500 r/min. When the rotating speed is reduced to 300 r/min, the grain size difference along the thickness direction decreases significantly. At 300 r/min, the hardness of the WNZ is homogeneous along the thickness direction while the hardness value at the bottom of WNZ is much lower than that at the middle and top at 400-500 r/min. Under the optimized process of 300 r/min-80 mm/min, the ultimate tensile strength of the joint can reach 71.57% of the base metal. The fracture location of tensile specimens mostly occurs at the interface between TMAZ and HAZ or at the bottom of the WNZ, which has typical plastic fracture characteristics.
Key words: thick-plate Al-Li alloy; stationary shoulder friction stir welding; heterogeneity; mechanical properties
