Transient Heat Transfer in a Chromium-Coated 7.62 Mm Gun Barrel Under Rapid Firing Conditions

This paper presents a numerical investigation of transient heat transfer in a chromium-coated 7.62 mm gun barrel under rapid firing conditions. A two-dimensional axisymmetric finite-element model is developed using COMSOL Multiphysics to simulate the unsteady thermal response of the barrel during successive firing cycles. The barrel wall is modelled as a multilayer structure comprising a steel substrate and an inner chromium coating, with their thermal properties assumed to be temperature-dependent. Transient thermal loads are imposed on the inner surface of the barrel in the form of time-dependent heat fluxes representing the interaction between high-temperature propellant gases and the bore wall. In contrast, convective heat transfer is applied at the outer surface. The numerical results provide detailed distributions of temperature in both radial and axial directions, as well as the temporal evolution of the inner wall temperature during single-shot and multi-shot firing sequences. The influence of rapid firing on thermal accumulation within the chromium coating and the steel substrate is analysed. The study highlights the role of the chromium-coated layer in modifying heat transfer through the barrel wall and its impact on peak temperature levels under repeated firing conditions. The proposed modelling approach offers a useful tool for evaluating thermal behaviour and supporting the thermal design and durability assessment of small-calibre gun barrels.