Ferritic-austenitic duplex stainless steel

The ferritic-austenitic duplex stainless steel addresses high strength and ductility challenges by optimizing alloying elements and phase ratios, resulting in cost-effective materials with minimized processing defects.

JP2026091158APending Publication Date: 2026-06-03NIPPON STEEL CORPORATION
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Patent Information

Authority / Receiving Office
JP · JP
Patent Type
Applications
Current Assignee / Owner
NIPPON STEEL CORPORATION
Filing Date
2024-11-22
Publication Date
2026-06-03

AI Technical Summary

Technical Problem

Conventional duplex stainless steel materials face challenges in achieving high strength and ductility while minimizing shape defects during processing, often due to high alloy content and nitrogen levels, leading to increased costs and processing issues.

Method used

A ferritic-austenitic duplex stainless steel composition is developed with controlled alloying elements, including reduced nickel and nitrogen content, utilizing the TRIP effect, and specific ratios of DF and Md values to enhance tensile strength and ductility, while suppressing shape defects.

Benefits of technology

The new composition achieves high strength and ductility with reduced alloying costs, effectively minimizing shape defects during processing.

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Abstract

To provide a ferritic-austenitic duplex stainless steel material that is high-strength and high-ductility, and can suppress shape defects (springback) during processing at a low cost. [Solution] A ferritic-austenitic duplex stainless steel material having a composition based on mass, containing C: 0.001~0.050%, Si: 0.01~0.50%, Mn: 1.0~3.5%, P: 0.050% or less, S: 0.0300% or less, Ni: 1.5~3.0%, Cr: 19.6~22.5%, Mo: 0.01~1.00%, Cu: 0.01~1.00%, N: 0.010~0.090%, with the remainder being Fe and impurities, having a DF value represented by a specific formula of 50.0~75.0, an Md value represented by a specific formula of 50.0~150.0℃, and an austenite phase of 50.0~65.0 volume%.
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