Achieving property differentiation and enhanced strength-plasticity in tailor rolled blank of aluminum alloy by variable gauge rolling and heat treatment

Abstract

This research presents a novel method for preparing tailor rolled blanks of aluminum alloy (Al-TRB) by synergizing variable gauge rolling with heat treatment, achieving a remarkable property differentiation between thin and thick zones and enhanced strength-plasticity. After variable gauge rolling, there is a notable increase in both tensile and yield strengths across the zones, attributed to deformation strengthening, though elongation decreases. The process induces a pronounced property difference, with a tensile strength difference of 72 MPa, a yield strength difference of 100 MPa, and an elongation difference of 12.4 % between thin and thick zones. This property gradient is a fundamental advancement, offering a strategic advantage in automotive component manufacturing by allowing the properties of different parts on the same component to be matched according to their specific operational demands. Subsequent re-aging and bake-hardening treatments further enhance the strength-plasticity, elevating the tensile strengths of the thin and thick zones to 407 MPa and 329 MPa, respectively, while improving elongations to 13.4 % and 20.7 %. The strength increment is attributed to precipitation strengthening, while the elongation increment is due to dislocation recovery during re-aging and bake-hardening. The fundamental advancement of this research lies in the tailored property differentiation of Al-TRB, which not only surpasses the mechanical properties of conventional 6000-series Al-TRB but also provides a strategic advantage in automotive component manufacturing. This innovation enables the maximization of load-carrying potential by matching the properties of different parts on the same component according to specific operational demands, thereby enhancing overall vehicle performance and safety.