The Joule heat welding technique requires only current to join fine-scale materials together and is a useful way to create and repair electric circuits. During Joule heat welding, the temperature in the wire system increases, leading to grain growth and affecting the mechanical properties of the welded wires. This paper reports the grain growth of Cu wires during Joule heat welding and the mechanical properties of the welded wires. The diameter of a Cu wire was 25 μm, and the welded wires were subjected to tensile testing. Although the welded wires were broken outside the welds, the yield stress and fracture stress of the welded wires were two-thirds of the yield stress and fracture stress of the as-received Cu wire. The decrease in the yield stress and fracture stress of a Cu wire was due to its grain growth. Tensile testing of Cu wires heat-treated at various temperatures by current was also conducted. The region around the fracture position of the Cu wires was heated to around 900 °C during welding, and the grain there was found to have grown to about twice the size of that before testing.

中文翻译：

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焦耳热焊接过程中铜丝的晶粒长大

焦耳热焊接技术只需要电流即可将精细材料连接在一起，是创建和修复电路的有用方法。在焦耳热焊接过程中，焊丝系统中的温度升高，导致晶粒长大并影响焊丝的机械性能。本文报道了焦耳热焊接过程中 Cu 线的晶粒长大和焊接线的机械性能。Cu线的直径为 25μm，对焊丝进行拉伸试验。尽管焊丝在焊缝外部断裂，但焊丝的屈服应力和断裂应力是原样铜丝屈服应力和断裂应力的三分之二。Cu线的屈服应力和断裂应力的降低是由于其晶粒生长。还对通过电流在不同温度下热处理的铜线进行了拉伸测试。焊接过程中，Cu 丝断裂位置周围的区域被加热到 900 °C 左右，发现那里的晶粒已经长大到测试前的两倍左右。