Laser weld-induced formation of amorphous Mn–Si precipitate in 304 stainless steel

Abstract

We report the formation of partially amorphous Mn-Si precipitates due to laser welding of face centered cubic (fcc) 304 stainless steel. Transmission electron microscopy and precession electron diffraction studies in the heat affected zone (HAZ) of t he weldment indicate the formation of these precipitates in grain interiors. Precipitates have MnSi stoichiometry and the partially crystalline regions have a lattice constant of 0.45 nm. It is surmised that the rapid cooling rates during the laser weld melt pool solidification process may be sufficient to inhibit the complete crystallization of these precipitates.

Materials qualification through the Nuclear Science User Facilities (NSUF): a case study on irradiated PM-HIP structural alloys

“…The nuclear industry is seeking to replace traditional castings or forgings with PM-HIP manufacturing for LWR (Gandy et al, 2012;Gandy et al, 2019) and small modular reactor (SMR) (Gandy et al, 2019) internals, pressure vessels (Morrison et al, 2019), and secondary side components. PM-HIP offers numerous advantages over conventional alloy fabrication, including an equiaxed, fine-grained structure (Clement et al, 2022a;Clement et al, 2022b), chemical homogeneity (Yu et al, 2009;Ahmed et al, 2013;Shulga, 2013;Ahmed et al, 2014;Gandy et al, 2016), exceptional mechanical properties (Metals and and Ceramics Information Center Report No, 1977;Atkinson and Davies, 2000;Rao et al, 2003;Shulga, 2012;Shulga, 2014;Guillen et al, 2018;Morrison et al, 2019;Barros et al, 2022) especially at high temperatures (Bullens et al, 2018;Getto et al, 2019), greater irradiation resistance (van Osch et al, 1996;Lind and Bergenlid, 2000;Rodchenkov et al, 2000;Lind and Bergenlid, 2001;Clement et al, 2022a;Clement et al, 2022b), fewer defects (Gandy et al, 2012;Gandy et al, 2019), and near-net-shaped fabrication which reduces reliance on welding and machining (Mao K. S. et al, 2018;Mao et al, 2021). PM-HIP-manufactured ferritic steels, austenitic steels, and Ni-based alloys are already qualified for nonnuclear applications, alongside castings and forgings, in the ASME Boiler and Pressure Vessel Code (BPVC), Section 2.…”