Microstructure, tensile and creep properties of an austenitic ODS 316L steel

Abstract

ODS 316L, an austenitic grade of oxide-dispersion-strengthened (ODS) steel, was fabricated by mechanical alloying, hot isostatic pressing and forging. A broad characterisation study was conducted, including High-Resolution Transmission Electron Microscopy (HRTEM) to investigate the microstructure and the interface between oxide particles and the 316L matrix. Mechanical properties at room and elevated temperature were determined by means of tensile and creep tests. Data from the room temperature and high temperature tensile tests were compared with those from conventional 316L. Creep data were used to assess the performance of the ODS 316L against standard assessment codes and in comparison with conventional 316L. Higher mechanical strength was found for the ODS 316L, in comparison to conventional 316L, at room temperature. UTS at high temperature was lower for the ODS 316L, but its yield strength was twice that of 316L. It was found that, although compliant with the Design and Construction Rules for mechanical components of nuclear installations (RCC MR) [1] code for the creep test conditions imposed, the ODS 316L studied is lower strength and has shorter rupture-life than its conventional counterpart. The HRTEM investigations indicated that small oxide particles, <15 nm in size, were coherent or semi-coherent with the steel matrix, whilst larger particles were incoheren

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