Austenitic alloy
JPWO2026014296A1Active Publication Date: 2026-01-15NIPPON STEEL CORPORATION
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Patent Information
- Application Number
- JP2025550437
- Authority / Receiving Office
- JP · JP
- Patent Type
- Applications
- Current Assignee / Owner
- Priority Date
- 2024-07-11
- Filing Date
- 2025-06-30
- Publication Date
- 2026-01-15
- Estimated Expiration
- 2045-06-30
AI Technical Summary
Technical Problem
Existing austenitic alloy materials exhibit insufficient resistance to stress corrosion cracking (SCC) in highly corrosive sour environments, despite having improved SCC resistance as per International Publication No. 2018/225869, and there is a need for further enhancement.
Method used
The alloy composition includes specific elements with controlled sulfur content and inclusion characteristics, such as low-sulfur inclusions with a defined Fn1 value and size distribution, to enhance SCC resistance.
Benefits of technology
The proposed alloy composition significantly improves SCC resistance by minimizing the number and size of high-sulfur inclusions, thereby reducing the occurrence of SCC in sour environments.
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Abstract
The present invention provides an austenitic alloy material with excellent resistance to SCC (Steel Chloride Crushing). The austenitic alloy material of this disclosure contains, by mass%, Cr: 19.0-28.0%, Ni: 28.0-37.0%, and Mo: 2.00-6.00%, with an Fn1 defined by formula (1) of 5.0 or higher, and a number density ND1 of fine low-S inclusions with an equivalent circular diameter of 2.0-10.0 μm of 3.0 inclusions / mm². 2 The above conditions are met, and the number density ND2 of coarse, low-S inclusions, which are inclusions with an Fn1 of 5.0 or higher and an equivalent circular diameter greater than 10.0 μm, is 2.0 inclusions / mm³. 2 The following conditions apply to high-sulfide inclusions: Fn1 is less than 5.0, and the equivalent circular diameter is 2.0 μm or larger; the number density ND3 is 2.0 inclusions / mm². 2 The following applies: Fn1=(Mg+Al+Ca+Ti+V+Mn) / S (1) Here, the elemental symbols in equation (1) are substituted with the mass percentage of the elemental content in the corresponding inclusion.
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