TC11高強(qiáng)鈦合金激光焊接接頭的顯微組織與力學(xué)性能Microstructure and mechanical properties of high-strength TC11 titanium alloy joints welded by laser beam

采用光纖激光進(jìn)行TC11鈦合金對(duì)接焊接，分析焊接接頭的顯微組織和力學(xué)性能。結(jié)果表明，TC11鈦合金焊縫為α′馬氏體組織，從母材至熔合線組織由α+β逐漸向α′ 轉(zhuǎn)變；隨著熱輸入量的增加，焊縫柱狀晶尺寸變大，馬氏體分布更加密集交錯(cuò)，同時(shí)熱影響區(qū)寬度增加，粗晶區(qū)晶粒尺寸變大；2 mm厚TC11鈦合金在焊接速度2.0 m/min、激光功率2.8 ~3.2 kW的工藝參數(shù)下得到的焊縫成形良好；焊縫硬度高于母材硬度，并隨熱輸入量的增加而增大；焊接接頭抗拉強(qiáng)度達(dá)到母材的97 %以上，塑性明顯下降，低于母材的50%，焊縫斷口形貌為低塑性沿晶斷裂特征。

The titanium alloy TC11 was welded by fiber laser beam, the microstructure and mechanical properties of the laser welded TC11 joints with different welding parameters were studied. The results show that the microstructure of weld metal consists of α′ martensite. From the base metal to fusion line, the microstructure evolves from α+β phase to α′ phase. With increasing the heat input, the size of columnar dendrites increases, the distribution of α′ martensite becomes more dispersive, the width of HAZ and grain size in coarse grain zone increase. Under the welding speed of 2.0 m/min and laser power of 2.8-3.2 kW, the sound welds of 2 mm thick TC11 alloy were obtained. The hardness of the weld increases with increasing the heat input. The tensile strength of welded joints reaches at least 97% of that of the base metal, while the plasticity decreases significantly. The fracture topography of welded joints shows brittle fracture character.

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