Original Article

The interface microstructure evolution and mechanical properties of S32168/Q345R composite plate under different rolling parameters

¹ State Key Laboratory of Advanced Stainless Steel, Taiyuan University of science and technology, Taiyuan 030024, PR China
² School of Mechanical Engineering, Taiyuan University of Science and Technology, Taiyuan 030024, PR China
³ Taian Quality Technical Inspection and Testing Institute, Taian 271000, PR China

^* e-mail: This email address is being protected from spambots. You need JavaScript enabled to view it.

Received: 24 September 2025
Accepted: 18 March 2026

Abstract

The interface bonding strength of S32168/Q345R is affected by different process parameters as a composite plate of a pressure vessel. Previous research has focused on the influence of rolling parameters in governing both grain structure optimization and element diffusion on bonding strength but has not deeply explored the nonlinear relationship between rolling speed and interface bonding performance and the coupling effect of temperature and deformation heat on bonding properties. In this work, S32168/Q345R composite plates were prepared by hot rolling with different rolling speeds and reductions, and the microscopic experiments and mechanical properties of the composite plates after rolling were tested. The experimental results indicate that the bonding strength ranges from 390.9 to 548.6 MPa, which is much higher than the 210 MPa required by the international pressure vessel plate. This study shows that different rolling parameters act on the dynamic recrystallization and the heat diffusion affected by the deformation heat and deformation time so as to realize the microstructure optimization and performance optimization. In addition, the evolution of the interface microstructure is dominated by carbon migration: carbon loss on the Q345R side forms a ferrite decarburization layer, and Cr₂₃C₆ and TiC₂ carbides are formed on the S32168 side. This research elucidates the mechanisms by which various rolling parameters govern bonding strength and explores the formation process of carbonized inclusions and decarburization layer thickness and the influence on the interface bonding strength.