The brittleness of dissimilar NiTi-stainless steel (SS) welds caused by intermetallic compounds (IMCs) network limits their application in medical field. Inserting interlayer and special assembly are high-cost but still hard to eradicate the formation of IMCs. This work realized NiTi-SS wire joints with a high strength using laser welding-brazing mode through beam defocus and large offset. The effect of laser beam offset on joint appearance, microstructure, tensile strength and fractography was investigated. In welded-brazed joints, a fusion zone (FZ) of only one base metal formed while multilayered reaction microstructure at the brazed interface was observed. Without beam offset, a typical FZ was dominated by Ni₃Ti+Fe₂Ti IMCs network. The tensile strength was improved from 176.6 MPa of conventional welding mode without offset to 329.5 MPa of welding-brazing mode with 0.4-mm offset to SS side. The joint welded with large offset fractured at the brazed interface with a mixed ductile-brittle fracture; while brittle fracture inside the IMCs network of FZ was observed in the joint welded without beam offset. The enhancement of joint strength was attributed to the eradication of IMCs network in the FZ and a reaction layer with less Ti–Fe brittle IMCs. This welding-brazing mode can be applied to suppress the overall brittleness of NiTi-SS joints without using any interlayer.

由金属间化合物（IMCs）网络引起的异种NiTi-不锈钢（SS）焊缝的脆性限制了它们在医学领域的应用。插入中间层和特殊组装成本高，但仍难以根除 IMC 的形成。这项工作通过光束散焦和大偏移，使用激光焊接-钎焊模式实现了高强度的 NiTi-SS 焊丝接头。研究了激光束偏移对接头外观、微观结构、拉伸强度和断口的影响。在焊接钎焊接头中，仅形成一种母材的熔合区 (FZ)，同时在钎焊界面处观察到多层反应微观结构。在没有光束偏移的情况下，典型的 FZ 以 Ni ₃ Ti+Fe _{2 为主}Ti IMC 网络。拉伸强度从无偏移的传统焊接模式的 176.6 MPa 提高到向 SS 侧偏移 0.4 mm 的焊接-钎焊模式的 329.5 MPa。大偏移量焊接接头在钎焊界面处出现韧性-脆性混合断裂；而在没有梁偏移的焊接接头中观察到 FZ 的 IMCs 网络内部的脆性断裂。接头强度的提高归因于 FZ 中 IMCs 网络的消除和 Ti-Fe 脆性 IMCs 较少的反应层。这种焊接-钎焊模式可用于抑制 NiTi-SS 接头的整体脆性，而无需使用任何中间层。