Innovative approach to improve fatigue performance of automotive components aiming at CO2 emissions reduction

ended

Cars are responsible of 25% of CO2 emissions in the EU. To reduce these emissions, EU established a mandatory target, to be reached in 2020, of 95 g CO2/km (30% lower than the average CO2 emissions in 2012). Vehicle lightweight is the main alternative to reduce CO2 emissions. Crankshaft is the heaviest special steel component in a vehicle. So, its weight reduction potential is high. The crankshaft downsizing must be performed taking into account that engine torque can not be reduced. So, if crankshaft is downsized, the steel fatigue limit must be increased to guarantee the required crankshaft in-service performance. This INNOFAT project is focused on crankshafts manufactured with microalloyed steels, but the obtained results may be extrapolated to other automotive components (camshafts, gears, common-rails...). Two different approaches are considered to improve the component fatigue performance: 1) steels with improved isotropy and 2) steels with higher strength. In the first case, different isotropy levels will be evaluated to determine which of them leads to the best fatigue performance. The second approach is based on a new high strength microalloyed steel (UTS>1.050 MPa) up to now only manufactured at laboratory scale. Along the INNOFAT project, the crankshafts manufacturing process (from hot forging to different machining operations) will be studied at laboratory scale. Finally, the most suitable steel from each approach will be chosen to manufacture and test real crankshafts in order to estimate the weight reduction that could be achieved. At the end of the project, some guidelines will be elaborated in order to facilitate the industrial implementation of the developed steels.