Review of Damage Evaluation and Remanufacturing for M. Hayakawa Research Center for Structural Materials, National Institute for Materials Science (NIMS) Developing a Foundation for MHydrogen-related Equipment Y. Ono 1, 2, K. Wada1 Research Network and Facility Services Division, National Institute for Materials Science (NIMS) 2 Research Center for Structural Materials, National Institute for Materials Science (NIMS) 66PP33--1177 PP33--1188 To investigate the microstructure and damage of friction-fatigued carburized martensitic steels for the reliability of remanufacturing - a key green innovation technology for achieving a carbon-neutral, circular economy. The retained austenite phase and residual stress were characterized by X-ray diffraction (XRD). We evaluated their changes before and after roller pitching tests, and before and after the operation of the gear parts. Moreover, the development of functional recovery technology for surface treatments is crucial for remanufacturing. Laser hardening (LH), a type of surface treatment method, is known to be able to reform the partial surface of metals. This study focuses on the use of the laser hardening to allow the repair of friction-fatigue damage in used carburized martensite steel gears. As the surface of the fatigued specimen was rapidly heated by the laser and then cooled, the thin hardening layer quenched the surface layer. In addition, prior austenite grain refinement and restoration of the retained austenite phase in the laser hardening quenched layer were realized for the friction-fatigued specimen. Exploiting these characteristics, the friction-fatigued specimens were reheat-treated with the laser hardening; as a result, the number of cycles to failure increased by 3.8 times compared to that before the laser hardening treatment. For remanufacturing, the LH technique incurs lower environmental and processing costs than other surface treatments and is particularly beneficial when applied to gears and bearings, which are especially susceptible to wear and tear. Hydrogen is expected to be an essential secondary energy source for achieving carbon neutrality. To implement hydrogen in society, Japan launched “the Green Innovation Fund projects”. One of them is the Large-scale Hydrogen Supply Chain Establishment project. To make the cost of supplying hydrogen competitive with fossil fuels, a group of companies is working on this project to commercialize a large-scale hydrogen supply chain. On the other hand, to reduce the cost of liquefied hydrogen, it is important to establish cryogenic and hydrogen technologies for larger supply facilities. Therefore, in another project, NIMS is planning to install a materials evaluation facility to support the R&D activities of companies or newcomers to the hydrogen industry. The contents of NIMS project† will be presented in this presentation. †The results in this presentation were obtained primarily as a result of work commissioned by New Energy and Industrial Technology Development Organization. 2, M. Hayakawa 2, M. Hibi 1, T. Shimizu 1 and H. Katayama 2 Poster Presentation ｜NIMS Award Symposium 2023aterial Evaluations to Support R & D on Liquefied P3 ｜ EvaluationMaterial Sustainability
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