Surface integrity in titanium alloy cutting: A comprehensive review

Surface integrity has a critical impact on the functionality and performance of machined parts. Titanium alloys exhibit distinctive surface integrity characteristics and theoretical frameworks in cutting processes due to their unique crystalline structure and special physical and mechanical properties. Establishing a dedicated theoretical system for cutting-induced surface integrity tailored to titanium alloys holds substantial academic value and profound implications for engineering applications. In recent years, the deep integration of mechanical and materials sciences and advanced detection technologies has continuously driven innovative advancements in the theoretical understanding of surface integrity in titanium alloy cutting processes. Meanwhile, emerging technologies like 3D printing, energy-field-assisted cutting and clean cutting have also introduced new development opportunities for surface integrity investigations. However, systematic summaries of research achievements related to surface integrity in titanium alloy cutting remain insufficient, and a comprehensive framework is yet to be established. Therefore, this paper presents an independent and in-depth review of the latest advancements in the research on the surface integrity of titanium alloy cutting. First, the material characteristics of titanium alloys and advanced testing and characterisation methods are reviewed. Second, the deformation and microstructural evolution features and mechanisms of the machining-affected layer are analysed from various perspectives, including thermomechanical effects, dislocations, twinning, recrystallisation, phase transformations and texture evolution. The formation mechanisms and influencing factors of surface topographical characteristics are summarised. Subsequently, the mechanical characteristics, mechanisms and influencing factors of the machining-affected layer in terms of residual stresses and hardness are reviewed. Finally, the development of surface integrity theory under the influence of emerging technologies, such as additive manufacturing, clean cutting and energy-field-assisted cutting, is discussed. This review aims to provide theoretical support for constructing a cutting-induced surface integrity theory system tailored to titanium alloys and offers a valuable reference basis for optimising related manufacturing processes.