Abstract Cold-rolled (CR) type 347H austenitic heat-resistant steel is investigated in this study, and the main strengthening phase, NbC, experiences the procedures of dissolution and precipitation twice, with the increase… Click to show full abstract
Abstract Cold-rolled (CR) type 347H austenitic heat-resistant steel is investigated in this study, and the main strengthening phase, NbC, experiences the procedures of dissolution and precipitation twice, with the increase of deformation degree from 30% to 90%. Most of the primary NbC particles, remained during the solution treatment, dissolve in the austenitic matrix when the deformation degree is 30%, and rod-like NbC generates along the prior austenite grain boundary. Further deformation leads to the fragmentation and decomposition of the rod-like NbC. Until the cold rolling reduction reaches 90%, the dissolved NbC secondarily precipitates into nanoparticles and disperses throughout the martensite induced by deformation. The tensile strength of the 90% cold-deformed specimen, 1418 MPa, is enhanced by three times in contrast with the undeformed one.
               
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