The influence exerted by active cooling on the permanent connection formed as a result of electric arc welding

Abstract

The problem of temperature stresses is solved in the work. The process of electric arc welding with guaranteed penetration of steel plates of various thicknesses is simulated. The possibility of reducing residual stresses formed as a result of welding by applying heat removal from the surface of the near-weld region of a steel plate is being investigated. The temperature distribution is determined by solving a non-linear heat equation, in which the specific heat and thermal conductivity depend on temperature. The heat source is modeled using the double ellipsoid method proposed by John A. Goldak. The horseshoe-shaped heat sink follows immediately after the anode spot and is set by the heat flux in such a way that the main temperature of the plate does not decrease below its initial temperature. This limitation reduces the level of the temperature gradient, thereby reducing the stresses in the metal plate. To illustrate the effect of active heat sink, the temperature distribution in the top layer at the moment of termination of welding is compared with and without active heat sink. The material is assumed to be elastoviscoplastic, the deformations are small and consist of reversible and irreversible ones. Reversible deformations are related to stresses by the Duhamel - Neumann law. Irreversible strains increase when the von Mises plastic flow condition is satisfied, in which there is a plastic strain rate component responsible for the plastic flow viscosity. The elastic moduli (Young's modulus, Poisson's ratio) and the yield strength are assumed to be temperature dependent. The solution of the mechanical part of the problem is found by the method of simple iterations. For plates with different thicknesses, diagrams of residual stresses are given, located in the center of the plate from the seam to the periphery. As a result of the work, according to the obtained distributions of residual stresses in the plate material, it is concluded that the use of an active horseshoe-shaped heat sink from the near-weld zone when welding thin steel plates reduces residual stresses, therefore it is recommended to use in the welding process. The use of an active heat sink on the reverse side of the plate leads to an increase in the stress level, therefore it is not recommended for use.