Fatigue performance of tungsten inert gas (TIG) and plasma welds in thin sections

• Published in: International journal of fatigue Vol. 21; no. 6; pp. 587 - 601
• Main Authors: Branco, C.M, Maddox, S.J, Infante, V, Gomes, E.C
• Format: Journal Article
• Language: English
• Published: Oxford Elsevier Ltd 01-07-1999; Elsevier Science
• Subjects: Applied sciences; Exact sciences and technology; Fatigue; Mechanical properties and methods of testing. Rheology. Fracture mechanics. Tribology; Metals. Metallurgy; Modelling; Plasma and pulsed TIG; Thin sections; Welded joints; Welded joints; Fatigue; Modelling; Plasma and pulsed TIG; Thin sections; Fracture mechanics; Welded joint; Plasma welding; Fatigue strength; Mechanical properties; Weld toe; Carbon steel; GTA welding; Modeling; Thin wall
• ISSN: 0142-1123; 1879-3452
• DOI: 10.1016/S0142-1123(98)00084-X

The greatest potential for the use of TIG and plasma welding is in the joining of thin sections, less than 10 mm thickness. This may introduce an additional benefit from the fatigue viewpoint, since fatigue strength is expected to increase with a decrease in plate thickness.
Superior fatigue performance was confirmed for TIG and plasma transverse butt, cruciform and non-load carrying fillet welds of a carbon-manganese steel, all failing from the weld toe, justifying a one class increase in Eurocode 3.
Weld details, which failed by fatigue cracking in the weld throat, showed no influence of welding process.
Extensive measurements of the weld toe geometries confirmed that TIG and plasma welds had more favourable profiles than MMA welds, with lower weld toe angles and larger weld toe radii. Fracture mechanics modelling confirmed that the differences in weld toe geometry were consistent with the differences in fatigue life actually observed. Weld toe radius appeared to be more significant than weld toe angle.