Applied Thermal Engineering

(1)

Research paper

Three-dimensional simulation of 304L steel TIG welding process:

Contribution of the thermal ﬂ ux

Mouloud Aissani

^a

, So ﬁ ane Guessasma

^b^,^*

, Abdelhalim Zitouni

^a

, Rabah Hamzaoui

^c

, David Bassir

^d^,^e

, Younes Benkedda

^f

aMechanical and Metallurgical Division, Welding and NDT Research Center (CSC), BP. 64, Cheraga, Algeria

bINRA, Research Unit BIA, rue de la Geraudiere, 44316, Nantes, France

cUniversity of Paris-Est, Institut de Recherche en Constructibilite, ESTP, 28 avenue du President Wilson, 94234, Cachan, France

dInstitute of Industry Technology, Guangzhou&Chinese Academy of Sciences (IIT, Z&CAS), R&D Building, Haibin Rd, Nansha District, Guangzhou, China

eDepartment of Mechanical Engineering, University of Technology of Belfort Montebeliard, France

fDepartment of Mechanical Engineering, University of Saad Dahlab, BP 270, route de Soumaa, Blida, Algeria

h i g h l i g h t s

3D simulation of TIG welding validates bi-elliptic shape of surface heat source.

Peak temperature and heatﬂux density of 2180 K and 8.2 W/mm²are predicted.

Shape of weld bead stabilises after 11 s meaning quasi-static welding regime.

Fusion to heat affected zone volume ratio is as small as 5%.

a r t i c l e i n f o

Article history:

Received 22 December 2014 Accepted 12 June 2015 Available online 3 July 2015

Keywords:

Finite elements method Three-dimensional heatﬂux TIG welding

304L steel Heat affected zone Fusion zone

a b s t r a c t

In this study, we focus on the determination of the heat transfer properties in Tungsten-Inert-Gas welding (TIG) problem combining an experimental and a three-dimensional simulation approaches.

Optimal conditions are used to weld stainless steel (304L) sheets in butt configuration. Both instrumental monitoring and metallographic investigation of the welded material are carried out. The modelling of the heat source is performed by a mobile Gaussian surface source exhibiting a bi-elliptical shape. This source is implemented in a three-dimensionalfinite element model to compute heatflux and temperature fields. The comparison between the experimental and numerical thermal cycles shows a fair agreement.

Predicted temperaturefields and heat flux distributions are discussed. Conversion of isotherms into microstructural information shows that the size of the fusion zone is four times smaller than the heat affected zone dimension. The metallographic analysis confirms the expected microstructural evolutions but highlights differences between observed and predicted extents of the heat affected zone.

1. Introduction

The welded metal structures offer an important alternative to the assembly by riveting process. But the quality of welds remains a permanent preoccupation of the scientiﬁc and industrial commu- nity. Watanabe[1]reports in his review work that, in Japan, the welding technology evolved to support many of the industrial ap- plications, requiring to adapt the welding procedures and involved

materials. An extensive body of research work is dedicated to improve the quality of the welds; and still continue to increase towards safe in-service use of welded structures[2e5]. Lant et al.

[2] mention that development of adequate procedures is still a concern in weld repair in order to extend the lifetime of defective components beyond the temporary repair policies. In the same line of thought, Aloraier et al.[4]report several welding techniques to void excessive residual stress in weld repair. The authors point out also the increasing interest on ﬁnite element computation as a technique providing better knowledge of the welding processes and related physical and structural effects. One of the critical issues that can be addressed byﬁnite element packages is residual stress

*Corresponding author.

E-mail address:soﬁane.guessasma@nantes.inra.fr(S. Guessasma).

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