Manufacturing of Parts in Ultra High Strength Steel Using Local Heat Treatment

In this paper the manufacturing of a side impact beam, with the aid of local heat treatment, is described. The beam has two areas where the risk of fracture is high. Two zones of the blank, corresponding to these areas, are therefore heat treated before stamping to reduce the risk of fracture. The material is a martensitic steel with a virgin tensile strength of 1200 MPa. The heat treatment is made by laser to an approximate temperature of 850° Celsius. This heat treatment reduces the strength of the material to a tensile strength of approximately 650 MPa after cooling. The formability is increased accordingly. The method of local heat treatment with the objective to increase formability in selected areas can be seen as an alternative to the use of conventional tailor welded blanks.