The Theory of Moving Sources of Heat and Its Application to Metal Treatments

Abstract The theory of moving sources of heat has been instrumental in providing the welding engineer with a scientific criterion of weldability of steels. The author outlines briefly the fundamentals of this theory and derives appropriate solutions for linear, two- and three-dimensional flow of heat in solids of infinite size or bounded by planes. Point, linear, and plane sources of heat are examined. The solutions obtained are then applied to welding problems. It is shown that these solutions are in good agreement with the experimental results, and that they afford a close analysis of the factors governing the heat flow in welding. The most interesting result of the theory, however, is the derivation of a single formula capable of predicting the time and rate of cooling with a fairly good accuracy for a wide variety of thicknesses of steel, ranges of temperature, and welding conditions. An attempt has been made also to show how this theory could be applied to other problems of metal treatment, such as rate of extrusion in continuous casting, or control of flame-hardening and continuous quenching operations.