Enhancement of Strength and Ductility in STS304/1050Al/STS304 Composite Plates by Controlling Hot-Rolling Speed

This study investigates the effect of hot-rolling speed on the microstructure and mechanical properties of STS304/1050Al/STS304 (304 stainless steel/1050 aluminum alloy/304 stainless steel) three-layer composite plates. The results show that as rolling speed increases, the tensile strength increases from 300.3 MPa to 366.2 MPa and the elongation after fracture increases from 42.96% to 50.56%, achieving simultaneous improvement in strength and ductility. At high rolling speeds, the strengthening of the STS304 layer is attributed to deformation-induced martensitic transformation and dislocation multiplication (17.2% increase in tensile strength), while the softening of the Al1050 layer is predominantly attributed to dynamic recovery (37.3% increase in elongation after fracture), which contributes to a synergistic “steel strengthening and aluminum softening” effect. The rightward shift in the intersection point on the work-hardening rate curves indicates enhanced uniform deformation capacity, and the coarsening of dimples on fracture surfaces is consistent with ductile fracture mechanisms. Appropriately increasing the hot-rolling speed represents an effective process route for optimizing the strength–ductility synergy of such steel/aluminum composite plates.