Optimum heat input control in girth welding of small diameter pipe

Abstract

Summary It is important to develop a mathematical model for determination of the optimum process parameters in welding fabrication. An algorithm for optimisation of process parameters to achieve the required temperature field on specimens has been developed. The optimisation of process parameters refers to the determination of optimum heat inputs, such as the arc current, to make the calculated temperature fields correspond to the required ones. That is to say, the objective function is defined as the optimisation problem of minimisation of the difference between the calculated and required temperatures. Non-linear programming methods, such as convex programming and the steepest descent method, are applied to solve the optimisation problem. Algorithms based on optimisation methods are shown to be sufficiently reliable for determination of the optimum heat inputs in gas tungsten arc or TIG welding of both plate and pipe specimens.