Identification of Parametric Envelopes for Keyhole Plasma Arc Welding of 2.1 Mm Ti-6AL-4V Sheet

Identification of parametric envelopes for keyhole plasma arc welding of 2.1 mm Ti-6Al-4V sheet
Aditya A Deshpande*, Andrew J Short, Wei Sun, D Graham McCartney,
Lei Xu, Thomas H Hyde
Department of Mechanical Materials and Manufacturing Engineering
University of Nottingham, Nottingham NG7 2RD, UK

 * Corresponding Author: aditya.deshpande@nottingham.ac.uk

 Abstract
The challenge of selecting suitable welding parameters has limited the application of keyhole plasma arc welding (PAW) in industrial applications. Stable keyhole welding is usually only achieved within a narrow parametric range and requires a delicate balance among a large number of variables. Due to advances in computing technology, the finite element (FE) method has become a powerful tool in simulating welding processes for example, in identifying welding sequences to minimise distortion and residual stresses. In this paper, experimentally determined stable keyhole plasma operating ranges, presented in the form of two-dimensional envelopes, for two of the three primary parameters (current, traverse speed and plasma gas flow rate), are compared with FE predictions. FE modelling was performed using the commercially available code SYSWELD to investigate PAW of 2.1 mm thick Ti-6Al-4V sheet. In the FE model, a three dimensional conical heat source was employed. The heat source definition was validated against experimental micrographs of fusion and heat affected zones. The effect of varying primary parameters on the formation of a stable keyhole was investigated and results will be presented to compare experimental parametric envelopes and the predictions of the FE model.

 Keywords: Keyhole plasma welding; Heat source fitting; parametric envelope; FE modelling