A Numerical Simulation Method Considering Solid Phase Transformation and the Experimental Verification of Ti6Al4V...

Area of Science:

• Materials Science and Engineering
• Computational Mechanics
• Welding Technology

Background:

• Ti-6Al-4V titanium alloy is crucial for marine engineering applications.
• Understanding microstructure, residual stress, and deformation in welded joints is vital for structural integrity.
• Existing models may not fully capture the complexities of phase transformation during welding.

Purpose of the Study:

• To develop a unified prediction model for Ti-6Al-4V welding processes, incorporating solid-state phase transformation.
• To quantitatively assess the effects of tungsten inert gas welding (TIG) and laser beam welding (LBW) on weldment properties.
• To validate the model's predictions against experimental data for microstructure, residual stress, and deformation.

Main Methods:

• Development of a finite element model using ABAQUS subroutine, including solid-state phase transformation.
• Experimental design involving TIG and LBW of 1.6 mm thick Ti-6Al-4V sheets.
• Experimental validation through microstructure observation, hardness testing, and residual stress measurement.

Main Results:

• Model predictions for phase composition closely matched experimental observations.
• Phase transformation significantly influences residual stress distribution within the weld area.
• Overall joint deformation is primarily dictated by the welding process, with phase transformation causing localized volume changes.

Conclusions:

• The established finite element model accurately predicts key characteristics of Ti-6Al-4V welds.
• Phase transformation plays a localized but important role in residual stress development.
• The model's outputs (phase composition, residual stress) can be integrated into fracture failure analysis for enhanced structural assessment.