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In order to meet new environmental regulations (i.e. mass of CO2 rejected in the atmosphere per km), car manufacturers are looking for new solutions to lighten chassis and structural parts in cars. High strength steels formed by hot stamping have proved to be good candidates for achieving better in-use performances together with a lighter structure. In particular, the martensitic stainless steel MaX fulfils the industrial targets for chassis parts in terms of mechanical and fatigue properties. For instance, from a cold formed baseline made of 600 MPa carbon steel, a 50 % mass reduction can be expected with a hot stamped suspension arm made of MaX and included a new clamshell design. However, those parts are often made of a complex assembly of different materials (high strength steels, aluminium and cast iron among others) which are subjected to aggressive environments in service. Therefore galvanic corrosion of those complex assemblies has to be evaluated.

A new Ni-free martensitic stainless steel (MSS) was developed for hot stamped automotive parts, especially in order to design lightweight chassis part. After hot stamping simulation, the material exhibited a 1.2 GPa ultimate tensile strength with a minimum of 10% total elongation, in the as-quenched condition (Q) without any tempering treatment (Q+T). Moreover the material's chemical composition was optimized to improve the ductility at low temperature and during high strain rate mechanical testing. As a result, no brittle fracture in impact testing at −40°C was observed, and a good behavior in crash was recorded. To further assess the material's performances, high cycle fatigue properties of the grade have been characterized including the effects of machining and surface treatments. Results show that the fatigue limits at 2 million cycles for a stress ratio of −1, for both bare and shot peened surface are quite high and in the range of 580 MPa to 640 MPa.