Austenitic stainless steel, which are well known for their excellent corrosion resistance, also exhibit a combination of outstanding characteristics, which make them particularly attractive in the automotive field. The strong strain hardening of austenitic stainless steels alloys make them very suited to produce high strengths by cold working. By adapting the degree of cold working, the change in ductility as well as in strength can be optimised for subsequent forming operations such as deep drawing, stretching or hydroforming. In most automotive applications, the combination of strength and formability is decisive. An example of these characteristics is the car prototype âNIDOâ? produced by Pininfarina, which has been exhibited for the first time at the world car exhibition in Paris (Mondiel de lâAutomobile â Paris 2004). For this prototype stainless steel type EN 1.4301 (AISI 304) has been used to manufacture the whole frame, by using sheet, tubes and bars. The project, which had the aim to have the maximum safety in a car of small dimensions, has seen the participation of various partners, among which Centro Inox of Milan (the Italian Stainless Steel Development Association) for the know-how on stainless steel. A new concept of chassis construction has also been developed, replacing the traditional floor tray, tunnel and firewall configurations with a structure in cellular stainless steel sheet. The advantages of this technology lie in its improved energy absorption capacity in collisions and excellent torsional stiffness. Cellular stainless steel sheet technology consists of a sandwich made up of four or more thin layers: flat sheets are used for outside sections, whereas for internal parts, two or more ribbed sheets were assembled together with their respective corrugations opposed.
