RESPONSE OF A WELD POOL TO PERTURBATIONS IN POWER

Automatic control of welding processes is rapidly developing and it is important to understand how the boundary of the weld pool responds to changes in the power. This paper shows how the response time depends on latent heat and the traverse speed of the heat source. For a slowly-traversing source, the solution is shown to be a superposition of the transient solution for a stationary source and the steady solution for a moving source. When the Peclet number, α = va/2D (v = traverse speed, a = equilibrium radius of a stationary pool, D = thermal diffusivity), is of O(1) the amplitude and response time vary considerably from the front to the rear of the pool. © 1979.