Temperature gradient mechanism: Overview of the multiple pass controlling factors

Laser forming offers the industrial promise of controlled shaping of metallic and non-metallic components for prototyping, the correction of design shape or distortion and precision adjustment applications. To date there has been a considerable amount of work carried out on two-dimensional laser forming, using multi-pass straight line scan strategies to produce a reasonably controlled bend angle in a number of materials, including aerospace alloys. A key area, however, where there is a limited understanding, is the variation in bend angle per pass during multi-pass Temperature Gradient Mechanism (TGM) based laser forming along a single irradiation track, in particular the decrease in bend angle per pass after many irradiations for a given set of process parameters. The research presented in this paper through empirical data and numerical simulation using Comsol MultiPhysics of the multi-pass laser forming of sheet mild steel, Ti6Al4V and AA5251 by CO2 laser offers a novel coherent picture of the key influencing factors and at which point in the bend evolution each is dominant.