Abstract Decreasing the impact speed can extend the effective heating time and escalate the heating rate. Additional flash is generated near the NiTi/SS interface due to the lengthening of the effective heating time. With decreasing impact speed, the plastic deformation zone of the SS is enlarged, and the microstructure in the heat-affected zone (HAZ) is increasingly coarsened, but those of NiTi demonstrate the opposite trends. In all of the NiTi/SS joints, the weld consists of a diffusion layer with a thickness that increases slightly from 1 μm to 1.7 μm as the impact speed decreases from 40 mm/s to 27.5 mm/s. The mechanical properties of the joint deteriorate with decreasing impact speed due to the increased remnant of semi-molten NiTi at the interface. The joint welded at an impact speed of 40 mm/s has the highest strength of 522 ± 41MPa with (7 ± 2)% rupture elongation, and it fractures via micro-void coalescence.

中文翻译：

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NiTi与不锈钢的冲击对焊-冲击速度效应检验

摘要 降低冲击速度可以延长有效加热时间，提高加热速度。由于有效加热时间的延长，NiTi/SS 界面附近会产生额外的飞边。随着冲击速度的降低，SS的塑性变形区扩大，热影响区（HAZ）的组织越来越粗化，而NiTi则表现出相反的趋势。在所有 NiTi/SS 接头中，焊缝由扩散层组成，随着冲击速度从 40 mm/s 降低到 27.5 mm/s，其厚度从 1 μm 略微增加到 1.7 μm。由于界面处半熔融 NiTi 的残余物增加，接头的机械性能随着冲击速度的降低而恶化。