Fabrication and Properties of Novel Multi-Layered Metal Composites

With the development of science and technology, more and more products with excellent quanlity and abundant functionalities have been exploited and provided. Inspired by the concept of "brick wall" structure or layer structure with alternated distribution of hard and soft phases discovered in nature creatures such as mother pearl shellfish, a entirely novel steel composite which not only can minimize the shortcomings of the original materials at the maximum extent, but also possess excellent mechanical performance as well as new physical properties, has been developed. Taking ultra-high strength maraging steel and 316L austenitic stainless steel as the original materials, the influence of deformation reduction under high vacuum on interfacial bonding strength and interface characteristics of heterogeneous multilayered metal composites was studied, and the fabrication feasibility of heterogeneous multi-layered metal composites was explored. The results showed that in the vacuum hot-pressing process, the interfaces under different deformations were clear and straight. Slight mutual diffusion phenomenon occurred in the hot-pressing process. Due to the difference of rheological properties of the original materials at high temperature, dynamic recovery and dynamic recrystallization occurred in the 316L layer, while deformed microstructure was dominant in the maraging steel layer. Combined with rolling process and heat treatment, bulk metal composites with 9 layers and 11 layers were prepared, respectively. The results of the three-point bending experiment showed that the crack occurred firstly at the outermost side of the multi-layer composites which withstood the tensile stress. Due to the passivation, delamination and bridging of heterogeneous interface in the multi-layer metal composites, the propagation path of crack was greatly extended and more energy was consumed, which showed excellent ability to block the crack propagation.