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51318-10612-In-service Embrittlement of 25%Cr Super Duplex Stainless Steel

Metallurgical investigations on a welded sample of 25% Cr super duplex stainless steel (UNS S32750) from a vessel that had operated above 300-350°C (570-660°F) for six months, resulting in brittle fracture.

Product Number: 51318-10612-SG
Author: Mikihiro Sakata / Ichiro Seshimo / Tomoaki Kiso / Toshiaki Okabe
Publication Date: 2018
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$20.00
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Metallurgical investigations were carried out on a welded sample of 25% Cr super duplex stainless steel (UNS S32750) taken from a vessel that had been accidentally operated above 300-350°C (570-660°F) for at least six months, which had resulted in brittle fracture. As a result of microstructure observations, no abnormalities were found in the ferrite/austenite balance and no intermetallic phases were observed in the sample, while Charpy impact tests at room temperature revealed quite a low absorbed energy in both, the base metal and the weld metal. These results indicated the occurrence of 475°C (885°F) embrittlement in the steel. De-embrittlement heat treatment trials were also performed to find out the effective temperature range. The aim of this paper is to draw attention to the risk of in-service embrittlement of duplex stainless steels, highlighting the difference in susceptibility to 475°C (885°F) embrittlement of the base metal and the weld metal.

Key words: 25% Cr super duplex stainless steels, 475°C (885°F) embrittlement, de-embrittlement heat treatment

Metallurgical investigations were carried out on a welded sample of 25% Cr super duplex stainless steel (UNS S32750) taken from a vessel that had been accidentally operated above 300-350°C (570-660°F) for at least six months, which had resulted in brittle fracture. As a result of microstructure observations, no abnormalities were found in the ferrite/austenite balance and no intermetallic phases were observed in the sample, while Charpy impact tests at room temperature revealed quite a low absorbed energy in both, the base metal and the weld metal. These results indicated the occurrence of 475°C (885°F) embrittlement in the steel. De-embrittlement heat treatment trials were also performed to find out the effective temperature range. The aim of this paper is to draw attention to the risk of in-service embrittlement of duplex stainless steels, highlighting the difference in susceptibility to 475°C (885°F) embrittlement of the base metal and the weld metal.

Key words: 25% Cr super duplex stainless steels, 475°C (885°F) embrittlement, de-embrittlement heat treatment

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51318-10568-Quality & Performance Review of Duplex Stainless Steel Products – An End Users Perspective

Product Number: 51318-10568-SG
Author: Janardhan Rao Saithala / Gurram Bhaskar Rao / Manoj Suryanarayana / Talal Nebhani / Pedro Rincon / Nasser Behlani / Mohammed Ghafri / Amjad Kharusi
Publication Date: 2018
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