Hot gas forming for advanced tubular automobile components. Opportunities and challenges

Today most industrial sectors are faced with several challenges such as the reduction of CO2 emission, the shortage of resources and the increasing individualization of products. This situation particularly appears in the automotive industry. To reduce CO2 emission of cars there is no alternative to decreasing weight. Advanced lightweight design implies new materials, innovative component design and finally new production methods. Based on this not only the CO2 emission during the operation phase becomes a focus, also the manufacturing process becomes more and more important. Following upcoming requests for lightweight materials, new design principles and energy and resource efficient production processes, conventional forming technologies are reaching their limits. By including temperature as an active temperature parameter into the production process, advanced final component properties are possible, forming limits can be extended and process chains can be shortened. This is valid particularly for hydroforming. Advantages and disadvantages of this technology are well known, and today there are a few typical automotive components in series production. Compared to a blank half shell design of car components, hydroformed profiles allow a flangeless design, the reduction of individual parts in a component and an excellent degree of material utilization. To implement high temperatures into this technology, alternative heat-resistant forming media are mandatory. The substitution of water by nitrogen increases the thermal process limits up to 1, 000C, but this also requires new systems engineering. This paper gives an overview on the development of hot gas forming technology and illustrates prospects and limits by means of automotive-related parts for metallic lightweight materials such as ultra-high strength and stainless steel, Aluminum or Magnesium. Beside the determination of temperature-related material characteristics, the research focused on process and tool des