Thermo‑mechanical creep with a theta projection model under steep thermal gradients: a scaled pilot steel ladle validation

High-temperature creep strongly influences the thermo-mechanical response of dry-jointed refractory linings in steel ladles. We develop a 3D joint-explicit meso-model of a scaled pilot ladle, coupling transient heat transfer with quasi-static mechanics and temperature-dependent properties. Creep of the working lining is implemented through a theta-projection formulation in a user subroutine and benchmarked against a Norton–Bailey power law. The model is validated using a dedicated pilot experiment, including thermocouple temperatures, circumferential shell strains (strain gauges and DIC), and shell uplift. Simulations reproduce the furnace cycle and show that viscoplastic deformation localises in the working lining, while the safety and insulation layers remain essentially elastic. Relative to Norton–Bailey, theta-projection provides smoother stress-relaxation at the hot face, better tracks the measured shell-strain evolution, and significantly reduces mesh sensitivity under steep thermal gradients, improving predictions of joint opening/closure and residual shell stresses.