Life and failure of oriented carbon nanotubes composite electrode for resistance spot welding

Abstract

In view of the poor weldability of electrodes in resistance spot welding (RSW) of galvanized steel sheets, the life of oriented multi-walled carbon nanotubes reinforced Cu matrix composites (Cu@MWCNTs/Cu) electrodes was studied, in which Cu coated multi-walled carbon nanotubes (MWCNTs) are arranged along the flow direction of working electric/force. By analyzing the macro/microscopic morphology, microstructure, hardness, texture and composition of the failed composite electrodes and the commercially CuCrZr electrode, the mechanism of the weldability enhancement and failure of electrodes was discussed. The results show that the life of Cu@ MWCNTs/Cu electrodes (2150 welds) is 3 times longer than that of CuCrZr electrode (600 welds), and the degradation rate is much slower. The hardness of Cu@MWCNTs/Cu electrodes is 30-40Hv higher. The content of recrystallized and recovery grains of Cu@MWCNTs/Cu electrodes is less. This is due to the pinning effect of MWCNTs, and straight and long MWCNTs are arranged along the electrical/force direction. These improve the hardness, mechanical properties, conductivity, and resistance to thermal deformation, cracking, and pitting of Cu@MWCNTs/Cu electrodes, which effectively slows down the failure rate and makes the spot welding life of Cu@MWCNTs/Cu electrodes longer. This work provides a new idea for the application of CNTs/Cu composites.

Optimizing mechanical properties of multi-walled carbon nanotube reinforced thermoplastic polyurethane composites for advanced athletic protective gear

“…In this configuration, the high aspect ratio MWCNTs can bear more of the load before reaching the interfacial shear stress limit and pulling out or fracturing. The aligned nanotubes effectively reinforce the polymer matrix along their longitudinal axis [39][40][41]. In contrast, the random MWCNT orientation resulted in overall lower and more isotropic mechanical properties.…”

Assessing Electrode Characteristics in Continuous Resistance Spot Welding of BH 340 Steel Based on Dynamic Resistance

“…This ensures that the Because the electrode is at high temperature for a long time and high electrode pressure must be applied to the weld plates, the electrode is prone to plastic deformation as the number of weld points increases. This phenomenon is accompanied by a gradual increase in the electrode tip diameter [9]. Firstly, the variance of the change in diameter of the electrode tip is small and increases at a high rate.…”

“…They tested electrode life and weldability by measuring geometric features, analysing mechanical properties and checking the electrode tip diameter at 88 or 176 weld intervals. Zheng et al [9] studied the failure process of oriented multi-walled carbon nanotube-reinforced copperbased composite electrodes by analysing the macro/micro-morphology, microstructure, hardness, texture and composition. The results show that the life of the composite electrode is three times longer than that of conventional CuCrZr electrodes, and the degradation rate is much slower.…”