Mechanical characterization of a new low carbon bainitic steel for high performance crankshaft

In the actual automotive environment, the need to increase the performances of materials is requiring extra engineering efforts. The possibility to develop new materials is very important. Indeed alternative solutions in terms of material choice allow designers to optimize their projects and keep low costs of production. Dealing with potential alternatives to traditional quenched and tempered steels for high stressed components, as just seen in previous work, bainitic grades could be a valid solution. This is particularly true if the mechanical performances are kept without compromise the economic savings of bainitic grades. So a detailed evaluation of the mechanical properties of these steels needs a further deepen also for applications requiring case hardening treatment. The scope of this article is to introduce and show the characterization phase of a new bainitic low carbon content for a high-performance crankshaft application. In details, a long-life fatigue resistance staircase test is performed after a gas nitriding treatment and the results are compared to the untreated material. The increment of the fatigue resistance is quantified and can be utilized by structural engineers to develop and optimized their projects. Moreover, the case hardened depth and microhardness profiles are collected and evaluated in terms of nitriding effectiveness (nitrogen diffusion).