(北京科技大學(xué) 材料科學(xué)與工程學(xué)院，北京 100083)
摘 要: 通過高溫拉伸試驗(yàn)研究Ti-6Al-4V(TC4)合金激光焊縫的縱向超塑性變形行為，采用掃描電鏡觀察超塑性變形前后焊縫的顯微組織。結(jié)果表明：TC4鈦合金激光焊縫具有良好的超塑性變形能力，在900 ℃、10−3 s−1工藝條件下伸長(zhǎng)率達(dá)到最大值397%；在超塑性變形過程中，原始焊縫的針狀馬氏體首先轉(zhuǎn)變?yōu)槠瑢訝畹摩?β組織，而后片層組織發(fā)生再結(jié)晶等軸化；隨著變形溫度升高或應(yīng)變速率降低，等軸化程度增大。
關(guān)鍵字: Ti-6Al-4V合金；激光焊接；超塑變形
laser welded titanium alloy
（School of Materials Science and Technology, University of Science and Technology Beijing, Beijing 100083, China）
Abstract:The superplastic deformation behavior of laser welded Ti-6Al-4V alloy by hot tensile tests were investigated, and the microstructures of the weld bead before and after superplastic deformation were observed by scanning electron microscopy (SEM). The results show that the laser welded TC4 joint has good superplasticity, and the maximal elongation of 397% is obtained at 900 ℃ and 10−3 s−1. During the superplastic deformation, the initial acicular martensite transforms into lamellar α+β phases. Then, dynamic recrystallization occurs and the grain expresses equiaxed trend. The equiaxed degree increases with increasing tensile temperature and decreasing strain rate.
Key words: Ti-6Al-4V alloy; laser beam welding; superplastic deformation
