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分别采用20,40,50,60 kHz不同频率的4组超音频直流脉冲TIG焊工艺焊接了厚度为1.5 mm的Ti2AlNb基合金板材。并采用X射线探伤手段对焊缝中的气孔缺陷进行检测,比如气孔的数量、尺寸及分布的位置;对于无缺陷的接头,观察接头的宏观和显微组织,测试接头硬度分布规律和拉伸性能。结果表明:采用脉冲频率为40,50,60 kHz的超音频直流脉冲TIG焊工艺对Ti2AlNb基合金进行焊接时,焊缝中气孔数量明显减少,尺寸减小,分布也由接头的内部变为接近表面的位置,在50,60 kHz的频率下能够得到没有气孔缺陷的焊接接头;接头各区域相组成不同,除B2基体以外,随母材向热影响区(HAZ)和熔合区(FZ)过渡,O相含量逐渐减少;由于相组成的变化,焊接接头的硬度分布规律为热影响区的硬度最高,母材次之,熔合区最低;对于4种不同频率的焊接工艺,采用频率为50 kHz时焊接接头抗拉强度最高,可达到926.20 MPa,加焊丝后可以在一定程度上进一步优化焊接接头的抗拉性能,降低同一焊接工艺下试样的性能分散性。
The Ti2AlNb-based alloy plates with a thickness of 1.5 mm were welded by four super-frequency DC pulsed TIG welding processes with different frequencies of 20, 40, 50 and 60 kHz, respectively. X-ray flaw detection method is used to detect the stomatal defects in the weld, such as the number, size and distribution of stomata. For defect-free joints, the macroscopic and microstructures of the joints are observed, and the rules of hardness distribution and tensile performance. The results show that when the Ti2AlNb-based alloy is welded by supersonic DC pulsed TIG welding with pulse frequencies of 40, 50 and 60 kHz, the number of pores in the weld decreases and the size decreases. The distribution also changes from the inside to the close Surface location, at 50,60 kHz frequency can be obtained without porosity defects welded joints; joints of the different phase composition, in addition to the B2 matrix, with the base metal to the heat affected zone (HAZ) and fusion zone (FZ) transition , The content of O phase decreases gradually. Due to the change of phase composition, the hardness distribution of welded joint is the highest in HAZ, followed by the base metal and the lowest in fusion zone. For the welding process with 4 different frequencies, the frequency is 50 kHz The tensile strength of the welded joint is the highest, which can reach 926.20 MPa. After the welding wire is added, the tensile properties of the welded joint can be further optimized to reduce the dispersibility of the specimen under the same welding process.