Cu-rich nanoprecipitates modified using Al to simultaneously enhance the strength and ductility of ferritic stainless steel

Abstract

• The Al-containing Cu-rich nanoprecipitates are rich in high-density dislocations. • The Al-containing Cu-rich nanoprecipitates simultaneously improve the strength and plasticity of ferritic stainless steel. • The enrichment of Al in the Cu-rich nanoprecipitates results in a new hardening mechanism. • Al inhibits the crystal structure transformation of the Cu-rich nanoprecipitates during deformation. • The addition of Al changes the blocking mechanism of BCC-Cu for dislocation. In the present work, we obtained coherent Cu-rich nanoprecipitates containing high-density dislocations by adding Al to Cu-bearing ferritic stainless steel after short-term aging. Such Cu-rich nanoprecipitates were rich in Al and had finer particle size and higher number density. Moreover, the high-density dislocations in the Cu-rich nanoprecipitates were capable of delaying the occurrence of plastic instability. Thus, the strength and ductility of Cu-bearing ferritic stainless steel were simultaneously improved.