Hot forming is a temperature- and time-dependent process. With this method, parts are formed in their soft state at elevated temperatures and then quenched in the tool.
The hot forming process consists of the following steps:
- Heat treatment in furnace
- Transfer from furnace to press and drawing tool
- Plastic hot forming
- Quenching in the closed, cooled die
Parts produced by hot forming are characterized by high strength, complex shapes and reduced springback effects. Optimal material behavior is achieved through the structural transformation of austenite into martensite. The most commonly used material in hot forming is Boron steel 22MnB5, which is available from many steel manufacturers.
There is a difference between direct and indirect hot forming.
In direct hot forming, the part is austenitized at a higher temperature, transferred to the cooled die and then deep-drawn. In this manner, complex shapes can be achieved as the material has excellent formability at high temperatures.
In indirect hot forming, the part is first deep-drawn without heating. Before the final shape has been obtained, the part is heated to the austenitizing temperature and the final drawing is carried out. This additional step extends the forming capabilities and allows for very complex geometries to be attained.
Hot forming has recently become important for the automotive industry in meeting specific requirements for higher crash safety and lower overall weight. Numerous car manufacturers use these processes to produce structural car body parts such as A- and B-pillars, tunnels, front and rear bumper beams, door sills, door beams, side-rails, roof rails and roof frames.
Hot forming is more complex compared to conventional forming. By using the hot forming process, parts with higher strength, higher geometrical complexity and minimized springback effects can be produced in a much shorter amount of time.
Further information on hot forming at AutoForm: