MATHEMATICAL MODELLING OF THERMOMECHANICAL STATE IN ADDITIVE MANUFACTURING AND WELDING OF TITANIUM ALLOYS FOR TRANSPORT ENGINEERING

Abstract

This study demonstrates a detailed investigation of residual stress distribution and thermomechanical behavior in Ti80 and Ti-6Al-4V titanium alloy components subjected to welding and post-weld treatments, integrating both experimental measurements and finite element simulations. The aim of the study is to evaluate the influence of welding sequence, thermal cycles, and temperature-dependent material properties on stress evolution, with particular emphasis on transverse and longitudinal residual stresses concentrated near weld toes. The relevance of this research is determined by the high demands for reliability, dimensional stability, and fatigue resistance of welded titanium components in transport, aerospace, and engineering applications. Significant anisotropy in stress distribution was observed along and across weld seams, highlighting critical regions prone to distortion or fatigue initiation. The novelty of this research lies in the comparative analysis of two titanium alloys under different welding conditions, combining experimental results with numerical simulations to provide a comprehensive understanding of residual stress development and thermomechanical responses. The work further demonstrates the effectiveness of post-weld heat treatment (PWHT) and local stress-relief procedures in mitigating residual stresses, enhancing both dimensional stability and fatigue performance. Practical implications of this study include guidance for optimizing welding parameters, implementing appropriate post-weld treatments, and improving the reliability and service life of high-performance titanium components in transport, aerospace, and engineering applications. The findings contribute to the broader understanding of the interplay between welding conditions, material behavior, and stress evolution, offering a foundation for improved predictive modeling and informed design decisions in welded titanium structures, and highlighting the significance of temperature-dependent properties in accurately forecasting residual stress fields and deformation patterns.

Keywords: Ti80, Ti-6Al-4V, residual stress, thermomechanical properties, post-weld heat treatment, FEM, welding, additive manufacturing.