针对航空领域粉末热等静压(HIP)TA15 钛合金复杂构件整体化制造的需求，为解决粉末 HIP 成形 TA15 与锻造 TA15 合金异种连接的性能匹配问题，采用氩弧焊(TIG)工艺制备了焊接接头，并系统研究其显微组织演变、力学性能匹配关系及断裂行为。 实验结果表明，焊接接头室温抗拉强度达 999 MPa，屈服强度 947.3 MPa，强度系数接近 1.0，与母材实现等强匹配；但伸长率(10.3%)较粉末本体下降约 24%，断裂位置分散于焊缝两侧。 225 ℃高温拉伸时接头抗拉强度约 836.6 MPa，塑性较室温提升 14.6%，呈现“强度损失小、塑性改善”特征。 高温持久性能测试显示，接头在 500 ℃/470 MPa 条件下寿命离散性大(30~60 h)，均断裂于焊缝，仅为母材的 60%左右，焊缝魏氏组织中粗大的集束边界成为薄弱环节。 低周疲劳测试结果表明，室温缺口试样(Kt=3)疲劳寿命达 14 167~17 848 周次；但 225 ℃试样疲劳寿命离散性显著(6 133~13 417 周次)，断裂位置由焊缝中心扩展至焊缝边缘。 断口分析揭示室温断裂为韧性机制，韧窝尺寸大且分布不均；225 ℃时韧窝细化均匀，动态回复机制激活使塑性提升；高温持久断口呈典型“冰糖状”沿晶断裂形貌，晶界 α 相成为裂纹扩展通道；疲劳断口呈现多源萌生、疲劳条带偏转及瞬断韧窝特征。 研究表明，粉末-锻件接头的组织异质性(锻件双态组织-焊缝魏氏组织-粉末网篮组织)是导致性能匹配差异的根本原因，焊缝魏氏组织的粗大集束边界在循环载荷下成为裂纹萌生源，而粉末侧细密的网篮组织表现出更优的抗疲劳性能。

To meet the demand for the integral manufacturing of complex powder hot isostatic pressed (HIP) TA15 titanium alloy components in the aerospace sector, and to address the property matching challenges in dissimilar joining between powder HIP TA15 and forged TA15 alloys, welded joints were fabricated using the tungsten inert gas (TIG) welding process. Furthermore, the microstructural evolution, mechanical property matching, and fracture behaviors of the joints were systematically investigated. The microstructural evolution, mechanical property matching, and fracture behaviors of the joints were systematically investigated. The experimental results indicate that the tensile strength of the welded joint is 999 MPa and the yield strength is 947.3 MPa at room temperature, with a joint efficiency approaching 1.0, indicating that the joint has equal strength to that of the base metals. However, the elongation (10.3%) is approximately 24% lower than that of the powder metallurgy (PM) substrate, with fracture locations randomly distributed on either side of the weld seam. During high-temperature tensile testing at 225 ℃,the tensile strength of the joint is approximately 836.6 MPa, with the ductility increasing by 14.6% compared with that at room temperature, indicating a slight strength reduction with improved ductility. High-temperature stress rupture tests at 500 ℃/470 MPa reveal significant scatter in rupture life (30~60 h), which is only approximately 60% of the base metal's life. All stress rupture failures occur at the weld seam, where the coarse colony boundaries within the weld's Widmanstätten microstructure act as a weak link. Low-cycle fatigue test results indicate that the fatigue life of room-temperature notched samples (Kt=3) reaches 14 167~17 848 cycles, whereas the fatigue life of the samples at 225 ℃ significantly varies (6 133~13 417 cycles), with the fracture location shifting from the weld center to the weld edge. Fracture analysis reveals that room-temperature fracture occurs via a ductile mechanism characterized by large and unevenly distributed dimples. At 225 ℃,the dimples become finer and more uniform, and the activation of dynamic recovery enhances the ductility. High-temperature stress rupture fracture displays a typical “rock-candy” intergranular morphology, with grain boundary α phases acting as crack propagation paths. Furthermore, fatigue fracture results in the initiation of multiple sources, deflected fatigue striations, and final fracture dimples. This study indicates that the microstructural heterogeneity of the joint (the bimodal microstructure of the forging, the Widmanstätten microstructure of the weld, and the basketweave microstructure of the PM substrate) is the fundamental cause of the property mismatch. The coarse colony boundaries within the weld's Widmanst ätten microstructure act as crack initiation sites under cyclic loading, whereas the fine basketweave microstructure on the PM side exhibits superior fatigue resistance.