Interfacial investigations on the microstructure evolution and thermomechanical behavior of explosive welded CLAM/316L composite

In this paper, a comprehensive study combined multiple characterizations and SPH nu-merical simulation was conducted to investigate the microstructure evolution, extreme thermomechanical behavior and consequences of the explosive welded CLAM/316L inter-face. The interfaces of the two welding materials underwent remarkable temperature rise and rapid cooling under high-speed collision conditions, forming a tight bond that presents a wavy structure with vortices. The SPH simulation adequately reproduced the heating and cooling process of the interface during explosive welding, revealing the high heterogeneity of the thermodynamic behavior during the impact process. Furthermore, the EBSD ana-lyses showed the perplexing evolution of crystal structure at the bonding interface with vortex, including ultra-fine grains, columnar grains, equiaxed grains, deformed grains and serious lattice distortion. By correlating the temperature histories and grain characteristics at different positions of the interface, the formation mechanism of diverse grains was revealed, referring to crystallization from liquid, recrystallization from the solid and plastic deformation. The recrystallization at the interface was closely related to the material properties, and the significant variations in dislocation density and plastic strain values at the interface, as well as the thermal softening of the material, could be explained by different degrees of dynamic recovery and recrystallization.(c) 2023 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).

Automated summary

A comprehensive study was conducted to investigate the microstructure evolution, extreme thermomechanical behavior, and consequences of explosive welded CLAM/316L interface using multiple characterizations and SPH numerical simulation. The study revealed a tight bond with a wavy structure and vortices formed at the interfaces of the two welding materials due to remarkable temperature rise and rapid cooling under high-speed collision conditions. The SPH simulation reproduced the heating and cooling process of the interface and revealed the high heterogeneity of thermodynamic behavior. The EBSD analyses showed complex evolution of crystal structure at the bonding interface with vortex, including ultra-fine grains, columnar grains, equiaxed grains, deformed grains, and serious lattice distortion. The formation mechanisms of diverse grains were correlated with temperature histories and grain characteristics, involving crystallization from liquid, recrystallization from solid, and plastic deformation. The recrystallization at the interface was closely related to material properties, and the variations in dislocation density, plastic strain values, and thermal softening could be explained by different degrees of dynamic recovery and recrystallization.