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Development of a 22%Cr Duplex Stainless Steel With Enhanced Weldability and Toughness Properties for Oil & Gas Applications

Duplex stainless steels were born and have been actively developed by European companies since 1935. Their properties make them very attractive compared to equivalent austenitic grades: higher resistance to stress corrosion cracking higher mechanical characteristics and lower alloy cost. They are today commonly used for Oil & Gas applications. However these materials cannot be used below -50°C (-58°F) because their toughness strongly decreases below this temperature. In addition they may require special precautions for welding in order to keep the ferrite content in heat affected zone lower than 65% as recommended by several standards.This paper will present the recent development of a 22%Cr duplex stainless steel grade with enhanced weldability and low-temperature properties. This material is based on the UNS S31803/S32205 designations and obtained by means of slight changes in the chemical analyses and production route compared to the conventional duplex grades. A strong increase in toughness values is obtained at low temperature pushing back the limits of use from -50°C (-58°F) to -100°C (-148°F). Toughness values obtained on samples up to 150 mm thick will be provided. In addition there is no need to control the minimum heat input to obtain the appropriate ferrite content in heat affected zone.This paper will describe the main service properties of this material focusing especially on corrosion and comparing its performance to a conventional 22%Cr duplex. The results of corrosion tests obtained in sour environment will be given. They were conducted on welded specimens in a solution containing 100 g/l NaCl at pH 4.5 under 0.5 bar H2S using the constant load test method. Stress corrosion cracking results obtained in synthetic seawater with and without cathodic charging will also be provided.Keywords: Stainless Steels; Duplex; Ferrite content; Oil & Gas; Low temperature; Weldability; H2S; Corrosion

Product Number: 51319-12931-SG
Author: Sandra Le Manchet
Publication Date: 2019
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$20.00
$20.00
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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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