Simulating microstructure evolution of battery tabs during ultrasonic welding

Abstract

a b s t r a c tUltrasonic welding offers ability to weld thin layers of malleable metals at low temperature and low power consumption. During ultrasonic welding, intensive material interactions occur due to the severe plastic deformation (SPD) and frictional heat generation, which leads to the microstructural change. Different grain microstructures have been observed after different ultrasonic welding conditions. Theory of the microstructural evolution was for the first time hypothesized as three regimes, namely SPD, dynamic recrystallization (DRX) and grain growth according to the material thermomechanical loading conditions. A novel metallo-thermo-mechanically coupled model was developed to model the temperature-dependent mechanical deformation and microstructural evolution during the ultrasonic spot welding process. The numerical analysis was carried out with a three-dimensional (3D) finite element model using DEFORM 11.0. The material constitutive model considered cyclic plasticity, thermal softening and acoustic softening. Dynamic recrystallization and grain growth kinetics laws were applied to simulate the microstructural evolution under different welding time durations. The simulation results demonstrated that the essential characteristics of the deformation field and microstructure evolution during ultrasonic welding were well captured by the metallo-thermo-mechanically coupled model. The numerical framework developed in this study has been shown to be a powerful tool to optimize the ultrasonic welding process for its mechanical properties and microstructures.

Cellular Automaton Simulation of Microstructure Evolution for Friction Stir Blind Riveting

“…The dDRX nucleus started to form at the moment when the process temperature increased to about 0.4T m (critical level of temperature for the onset of DRX [47,48]). In addition, the thermally driven grain growth during the cooling cycle was usually ceased when the temperature dropped to the level about 0.5T m [47,48]. The matrix microstructure was not completely replaced with the recrystallized grains, and the X DRX stopped at 0.66 (Fig.…”

“…It is most likely that the temperature in this region reaches up to the recrystallization temperature range. Severe shear deformation also indicates that it should have stored enough strain energy to trigger the DRX [47][48][49]. At the same time, if the material undergoes severe plastic deformation, there is a higher rate of nucleation compared to the rate of growth [50].…”

Ultrasonic Bonding of Multi-Layered Foil Using a Cylindrical Surface Tool

“…The micro-bonds develop owing to shear deformation in the latter bonding stage, resulting in a macroscopic plastic flow in the bonded region. In addition, a few studies have investigated the ultrasonic bonding of lithium-ion battery materials, such as copper sheet and aluminum sheet [9,10] and copper sheet and Ni-plated Cu sheet [11][12][13]. It has been revealed the initial micro-bonds are formed through the broken Ni layer; thereafter, plastic flow expands the bonded 2 of 12 region.…”

Ultrasonic Spot Welding of Nickel Foam Sheet and Aluminum Solid Sheet

“…A peak temperature of 87.9 °C is measured and the maximum welding duration is 0.35 s (energy of 70 J). Haddadi and Shen showed via experiments and FEM, respectively, that the temperature of the region neighboring the joint is ≈100 °C lower than that of the joint center. This indicates that the peak temperature is considerably lower than the solution temperature of Al/Ni at 639.9 °C.…”

“…Ultrasonic spot welding (USW) is a highly efficient and low‐energy‐consumption welding method, which is widely used in the electronics and automotive industries …”