Effect of Heat Input on the Microstructure and Mechanical Properties of Local Dry Underwater Welded Duplex Stainless Steel

• Published in: Materials Vol. 16; no. 6; p. 2289
• Main Authors: Hu, Yu, Shi, Yonghua, Wang, Kai, Huang, Jiqiang
• Format: Journal Article
• Language: English
• Published: Switzerland MDPI AG 13.03.2023; MDPI
• Subjects: Analysis; Austenite; Chromium; Cooling; Drainage; Duplex plating; duplex stainless steel; Duplex stainless steels; Energy conservation; flux-cored arc welding; Grain boundaries; Grain size; Grooves; Iron compounds; local dry underwater welding; mechanical performance; Mechanical properties; Metals; Microstructure; Nuclear energy; Nuclear power plants; Plastic properties; Recrystallization; Stainless steel; Tensile strength; Underwater; Welding; duplex stainless steel; microstructure; flux-cored arc welding; local dry underwater welding; mechanical performance
• ISSN: 1996-1944; 1996-1944
• DOI: 10.3390/ma16062289

Duplex stainless steel welded metals were underwater local dry prepared on S32101 lean duplex stainless steel trapezoidal groove plates with a self-made drain cover employing Supercore 2205P flux-cored filler wire. Different heat inputs were employed to investigate the effects on mechanical characteristics and the microstructure of welded metals. The results demonstrated that as the heat was applied, austenite concentrations in the weld metals increased. It was found that the austenite concentration and the fraction of Σ3-austenite twin-grain boundaries followed the same trends. With increasing heat input, the recrystallized ferrite and austenite grains initially decreased and subsequently increased, whereas the fraction of interphase boundaries between special ferrite and austenite exhibited the reverse trend. With a heat input of 1.4 kJ/mm, the toughness and plasticity of the weld metals were enhanced by an increase in austenite content, Σ3 recrystallized grains, and austenite twin-grain boundaries. The plasticity and tensile strength values of the welded metal changed more when the heat input was raised from 1.0 to 1.2 kJ/mm than when it was raised from 1.2 to 1.4 kJ/mm. Considering energy conservation, it is recommended to adopt 1.2 kJ/mm for welding heat input.