An improved simulation of temperature field in PMHW of Ti-6Al-4V alloy

Abstract

This article describes a coaxial plasma–MIG hybrid welding (PMHW) method to improve the welding quality of titanium alloy plates. Aiming at the temperature field analysis of a Ti-6Al-4V alloy plate in the PMHW process, an improved hybrid heat source model capable of accurately characterising the heat input of a hybrid arc on workpieces and the arc deflection phenomenon, is proposed. Experiments were conducted on 4-mm Ti-6Al-4V plates in PMHW surfacing, and a corresponding simulation analysis was performed. To calculate the weld geometry, a weld pool shape was used in accordance with the experimental results. The results showed that, as plasma current increased from 60 to 80 A, the weld reinforcement and offset $\Delta d$ decreased, and the size of the weld pool increased. Plasma arc power had a greater effect on the length than on the width of the molten pool. Hybrid arcs had a stronger penetrating ability; hence, achieving deep penetration welding and high welding efficiency in the PMHW of the Ti-6Al-4V alloy was easier. Microstructure analysis showed that the Ti-6Al-4V alloy base metal zone was organised by α- and β-phase transformations; β grains in the weld zone were internally formed by a mixture of Weischer tissue and net basket tissue; and the size of β grains in the heat-affected zone decreased with the increase in the distance from the weld.

Keywords:

• Plasma–MIG hybrid welding
• modeling and simulation
• temperature field
• titanium alloy

Acknowledgments

The generous support of Guangdong Welding Institute (China-Ukraine E.O. Paton Institute of Welding) is also highly acknowledged.

Disclosure statement

The authors declare no conflicts of interest.

Additional information

Funding

This work was supported by the Natural Science Foundation of Guangdong, China (No. 2021A1515011773), Guangzhou Science and Technology Plan Project Key R&D Plan (No. 2023B03J1329) and the Enterprise Science and Technology Commissioner Funding Project of Guangdong, China (No. GDKTP2021024300).