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Mise en forme à froid de soupapes en acier inoxydable austénitique ou en superalliage base fer

Abstract : A valve is a complex part obtained today by hot forming from a steel bar. This research work was the occasion to study the feasibility of exhaust valve cold forming. Two main objectives : saving thermal energy and produce a near net shape part. Two problems to solve : limited material ductility and higher mechanical solicitation of the forging tools. Exhaust valves are usually in austenitic stainless steel and for some specific applications in Nickel base superalloy with higher characteristics but with a dissuasive cost. Between these two families, there are the Iron base superalloys with mean characteristics and costs. We will begin by a brief presentation of the project objectives and the state of the art. Then, from the existing alloy characterisation, we have developed new alloys obtained using the Cemef Custom Casting Platform (C3P). We have shown that these new alloys are able to be cold formed in valves. The forming process study permit to show the crack apparition risk and to study the influence of the process parameters. Finally, a micro scale simulation has shown the ductile rupture initiation.
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Submitted on : Wednesday, February 27, 2008 - 3:01:30 PM
Last modification on : Wednesday, October 14, 2020 - 4:02:43 AM
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  • HAL Id : tel-00259312, version 1

Citation

Olivier Séguy. Mise en forme à froid de soupapes en acier inoxydable austénitique ou en superalliage base fer. Mécanique [physics.med-ph]. École Nationale Supérieure des Mines de Paris, 2007. Français. ⟨NNT : 2007ENMP1500⟩. ⟨tel-00259312⟩

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