Abstract
In this study, Submerged Arc Welding (SAW) and Gas Metal Arc Welding (GMAW) processes were used in multi-pass welding of 33 mm thickness super duplex stainless steel plates. Recommended and higher than recommended arc energy and interpass temperatures were used. Both GMAW and SAW processes were able to produce large thickness weldments meeting the microstructural, mechanical, and corrosion resistance requirements, and also when using higher than recommended arc energy and interpass temperature. It was possible to reduce the number of welding passes by half when using higher than recommended arc energy and interpass temperature. The SAW process needed only half of the welding time required for the GMAW process to produce a weldment with nearly the same number of weld passes, when using recommended arc energy and interpass temperature. Based on the results of this investigation, the practical recommendations for welding large thicknesses should be revised and updated.
Highlights
Both Gas Metal Arc Welding (GMAW) and Submerged Arc Welding (SAW) processes were able to produce large thickness weldments meeting the microstructural, mechanical, and corrosion resistance requirements, and when using higher than recommended arc energy and interpass temperature
Nitrides were mainly located in the HAZ, but it was possible to observe them in weld passes 2, 4, 7, 8, and 10
Welding time produceaacomplete completeweldment weldment for for each passes is included in in thethe figure. It is well-known that both high energy input and successive reheating can promote the formation of intermetallics and secondary austenite, impairing the impact toughness and corrosion resistance of the weldments [7,8,9,10,11,12,13]
Summary
It is well-known that duplex and super duplex stainless steels show an excellent combination of strength, toughness, corrosion resistance, and stress corrosion cracking resistance [1]. In the oil and gas industry, these steels are used in on-shore production tubing and in off-shore subsea manifolds and pipelines, experiencing high internal pressures and external pressures due to their undersea location [2,5,6] In both industries, duplex and super duplex stainless steels are demanded in the form of large thickness plates and tubes, usually ranging from 20 to 40 mm in thickness. Corrosion resistance and mechanical properties can be severely impaired when the duplex and super duplex stainless steels are repeatedly reheated to the range of approximately 600 ◦ C to 1000 ◦ C, as happens in multi-pass welding. There is a real need for welding large thickness super duplex stainless steels in specific industries, and the weldments have to fulfill the desired properties and at the same time with the highest possible productivity. It is expected that the outputs of this work can contribute by adding complementary and valuable data about large thickness welding of super duplex stainless steels
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