Effect of welding segregation on microstructure and mechanical properties of regenerated weld for nanostructured bainite steel

Effect of welding segregation on retained austenitein regenerated weld for nanostructured bainite steel has been investigated by SEM, TEM and EBSD. Welding segregation resulted incoarse retained austenite that distributed at the boundary of the dendrite in the weld. The carbon content of coarse retained austenite is lower than that of the blocky-shape austenite, which reduces stability of the structure. The retained austenite in base metal is in submicronmeter size with a uniform distribution. By contrary, the size of retained austenite in the weld is in micronmeter, and the distribution is not uniform. As a result, the change of the retained austenite in the weld has important effect on the elongation rate of the weld.