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

We first 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 the weldment indicate the formation of Mn–Si precipitates in grain interiors. Precipitates exhibit Mn–Si 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. [Display omitted]