Austenitic Stainless Steel Composition for Low-Nickel High Strength
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Solution Overview
Problem
Conventional austenitic stainless steels face challenges in achieving high yield strength, formability, and price competitiveness due to high contents of high-priced alloying elements like nickel, which also affect productivity and stability.
Innovation Solution
Austenitic stainless steel with controlled compositions of C, N, Si, Mn, Cr, Ni, Cu, and Nb, within specific ranges, and satisfying Expressions (1) to (4), allowing for high yield strength, formability, and reduced nickel content.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If high contents of alloying elements like nickel are used to achieve high yield strength, then strength is improved, but price competitiveness deteriorates
Solution Approach 1:
The patent applies parameter changes by precisely controlling the composition ratios of alloying elements. Specifically, it limits nickel content to 0.5-12.0 wt%, chromium to 14.0-20.0 wt%, and manganese to 4.0-10.0 wt%, while maintaining specific relationships between elements (e.g., Cr ≥ 1.5×Mn + 4, Cr ≥ 1.2×Ni + 8) to achieve high yield strength without excessive nickel addition, thereby improving price competitiveness while maintaining strength
Solution Approach 2:
The patent creates a composite alloy system where multiple elements work synergistically. The specific composition ranges and relational expressions ensure that chromium, manganese, nickel, and other elements combine to produce austenitic stainless steel with high yield strength, replacing the conventional approach of relying heavily on nickel alone
2Strength
If high contents of alloying elements are used to achieve high yield strength, then strength is improved, but formability deteriorates
Solution Approach 1:
The patent controls the composition parameters to balance strength and formability. By limiting alloying element contents to specific ranges and maintaining relational expressions (e.g., Cr ≥ 1.5×Mn + 4), the steel achieves high yield strength while preventing excessive hardening that would compromise formability, enabling both properties to coexist
3Strength
If high contents of alloying elements are used to achieve high yield strength, then strength is improved, but productivity deteriorates
Solution Approach 1:
The patent optimizes composition parameters to improve hot workability and productivity. By controlling nickel to 0.5-12.0 wt%, chromium to 14.0-20.0 wt%, and manganese to 4.0-10.0 wt%, along with maintaining specific relational expressions, the steel achieves high yield strength while ensuring good hot workability that prevents cracks during hot rolling, thereby improving productivity
4Strength
If high contents of alloying elements are used to achieve high yield strength, then strength is improved, but stability deteriorates
Solution Approach 1:
The patent enhances stability by controlling composition within narrow ranges and establishing relational expressions between elements. The constraints (e.g., Cr ≥ 1.5×Mn + 4, Cr ≥ 1.2×Ni + 8, Mn ≥ 0.5×Ni + 2.5) ensure consistent austenitic phase structure and prevent unwanted transformations during processing, providing stable composition and properties
Data Source
AI summary
Disclosed is a high-strength austenitic stainless steel and a method for producing same, wherein the austenitic stainless steel has high productivity due to excellent hot workability thereof and a superior cost reduction effect due to a large decrease in content of nickel (Ni) which is a high-priced element, and has a yield strength of 450 MPa or more and an elongation of 45% or more after cold rolling and annealing and an ultra-high strength of 1800 MPa or more even after skin pass rolling, and a method for producing same.