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Abstract

The study of high-productivity submerged arc welding processes, with techniques involving up to 6 wires, examined the welding of medium thickness HSLA steels employed for the construction of large-diameter pipelines and the welding of very thick plate for offshore use. For medium thickness welds, tests indicated good mechanical strength and ductility. There were no alterations in toughness and ductility during Charpy-V impact tests but the type of flux used for the welding was critical. A marked deterioration of FATT was seen in the HAZ of Nb-Cr steels. Microstructural investigations in the WM zone revealed the dependence of shelf-energy and FATT on the oxides. Overall, the use of 6 wires was found to give the greatest increase in productivity. For very thick welds, good results were achieved from transverse tensile and lateral bending tests for multi-pass welds using 2,3 and 4 wires. Stress-relieving heat treatment had no effect and there was no variation in CV values in the HAZ with different techniques.

Additional information

Authors: ARISTOTILE R, Centro Sviluppo Materiali S.P.A., Roma (IT);ROSELLINI C, Nouva Italsider S.P.A., Centro Siderurgico, Via G.d'Acri. I-16152 Genova (IT)
Bibliographic Reference: EUR 12153 IT (1989) MF, 81 pp., ECU 4, blow-up copy ECU 7.50
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