Research on edge defects suppression of Mg/Al composite plate rolling: Development of embedded rolling technology

• The 'embedded composite rolling' technique is proposed to improve formability of mg/al composite. • The reduction of stress triaxiality at the edges of the plate is key to defect suppression. • The proposed process enhances edge bonding and tensile strength by 67.7 % and 118 %, respectively. • Increased grain boundary density and basal texture contribute to enhanced plate toughness. Edge defects significantly impact the forming quality of Mg/Al composite plates during the rolling process. This study aims to develop an effective rolling technique to suppress these defects. First, an enhanced Lemaitre damage model with a generalized stress state damage prediction mechanism was used to evaluate the key mechanical factors contributing to defect formation. Based on this evaluation, an embedded composite rolling technique was proposed. Subsequently, comparative validation was conducted at 350 °C with a 50 % reduction ratio. Results showed that the plates rolled using the embedded composite rolling technique had smooth surfaces and edges, with no macroscopic cracks observed. Numerical simulation indicated that, compared to conventional processes, the proposed technique reduced the maximum edge stress triaxiality of the plates from −0.02 to −1.56, significantly enhancing the triaxial compressive stress effect at the edges, which suppressed void nucleation and growth, leading to a 96 % reduction in damage values. Mechanical property evaluations demonstrated that, compared to the conventional rolling process, the proposed technique improved edge bonding strength and tensile strength by approximately 67.7 % and 118 %, respectively. Further microstructural characterization revealed that the proposed technique, influenced by the restriction of deformation along the transverse direction (TD), weakened the plastic flow in the TD and enhanced plastic flow along the rolling direction (RD), resulting in higher grain boundary density and stronger basal texture. This, in turn, improved the toughness and transverse homogeneity of the plates. In summary, the embedded composite rolling technique provides crucial technical guidance for the preparation of Mg-based composite plates.