Material property changes associated with laser forming of mild steel components

Laser forming is a technique developed over the last 5 years or so which allows the forming and bending of metallic components without the need for hard tooling. This makes it a potentially useful prototyping and limited production technique. The laser forming method makes use of the laser's ability to heat very localised regions of material very quickly. The large temperature gradients set up within the material create internal stresses, which result in permanent deformation. A variety of sharp folds and curved surfaces can be generated by this technique. Work carried out on this technique both by ourselves and others has tended to concentrate on developing control systems and mathematical models in order to gain an insight into the mechanics of the technique. An area neglected so far, however, is how the rapid and repeated heating and cooling cycles associated with laser bending alter material properties. If components produced by this technique are to be used in practice it is vital that any weaknesses (or benefits) imparted by the technique are identified. This paper gives a brief introduction on the general principles and applications of the laser forming technique. An analysis of the effects of the technique on the material properties of mild steel is then presented and this is followed by a discussion on how, in practice, components formed using the thermally based laser forming technique are likely to function in comparison to more conventionally produced parts.