Application of Sellars-Tagart constitutive law to modelling of stir-friction welding of CuCrZr plates

• Published in: Materials today : proceedings 2023, Vol.87, p.351-355
• Main Authors: Jha, Kaushal, Mehra, Vishal, Singh, R.N.
• Format: Article
• Language: English
• Subjects: Meshless hydrocodes; Plasticity models
• ISSN: 2214-7853; 2214-7853
• DOI: 10.1016/j.matpr.2023.06.425

Friction-stir welding (FSW) is a relatively new solid-state welding technique in which a non-consumable rotating tool is inserted between workpiece plates and travels along the line joining the workpieces. Thermal softening is induced in the workpieces by friction at workpiece-tool interface and leads to, along with the material dragging by tool, mixing of materials in the stirred zone. FSW avoids defects resulting from melting and recrystallization of the workpiece material. Numerical simulations are useful in understanding the FSW process. We report simulations, carried out using Smoothed Particle Hydrodynamics technique, of previously published FSW experiments of 15 cm by 6 cm CuCrZr plates. The CuCrZr alloy is represented as a viscoplastic material using Sellers-Tagert constitutive law which provides flow stress as a function of temperature, strain rate and a material-dependent deformation activation energy. Thermal effects are included via a heat generation model, a heat conduction model and heat loss model to the backing plate. Simulations are done in two dimensions with the tool modeled as a moving and rotating boundary with a specified velocity and are carried out for 10–15 s. Width of the stirred zone where the particles of two plates mix is inferred from the final configuration along with temperature distribution of the plates. For the tool at 1000 rpm and 80 mm/min travel velocity, the width of the stirred zone was 24 mm and maximum temperature 12 mm away from the weld centerline was 760 K from simulations compared with 20 mm and 960 K experimentally resp.