Load-partitioning in an oxide dispersion-strengthened 310 steel at elevated temperatures. (5th December 2016) - Miao, Yinbin
Abstract: Here the high temperature tensile performance of an oxide dispersion-strengthened (ODS) 310 steel is reported upon. The microstructure of the steel was examined through both transmission electron microscopy (TEM) and synchrotron scattering. In situ synchrotron X-ray tensile investigation was performed at a variety of temperatures, from room temperature up to 800 °C. Pyrochlore structure yttrium titanate and sodium chloride structure titanium nitride phases were identified in the steel along with an austenite matrix and marginal residual α′ -martensite. The inclusion phases strengthen the steel by taking extra load through particle-dislocation interaction during plastic deformation or dislocation creep procedures. As temperature rises, lattice strain measurement implies that the load partitioning effect of conventional precipitate phases starts to diminish, whereas those ultra-fine oxygen-enriched nanoparticles continue to maintain a considerable amount of extra lattice strain. Introduction of oxygen-enriched nanoparticles in austenitic steel is shown to improve the high temperature performance, making austenitic ODS steels promising for advanced nuclear applications. Highlights: An austenitic oxide dispersion-strengthened stainless steel was developed and investigated for nuclear applications. Size distribution and orientation relationship of the ultra-fine oxygen-enriched nanoparticles were measured. In situ tensile tests were conducted at various temperatures to reveal the strengthening effect of precipitates. Only the ultra-fine oxygen-enriched nanoparticles are capable of retaining their strengthening effect at high temperatures. The austenitic oxygen dispersion-strengthened stainless steel showed advantageous mechanical strength. Graphical abstract: