Stainless Steel Foil Composition for Rolling and Oxidation Resistance
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Solution Overview
Problem
The challenge is to develop a stainless steel foil with improved manufacturability and high-temperature oxidation resistance and shape stability for use in exhaust emission control devices, where the existing Fe—Cr—Al-type stainless steel foils face difficulties in continuous tandem rolling due to low toughness, and reducing Cr and Al content compromises high-temperature performance.
Innovation Solution
A stainless steel sheet composition with reduced Cr content and added Mo, along with specific ranges of Ti, Zr, Hf, REM, Nb, V, B, Ca, and Mg, ensures improved toughness and maintains high-temperature oxidation resistance and shape stability, allowing for stable continuous tandem rolling and use up to 900°C.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If Cr content and Al content are decreased to improve toughness and enable continuous tandem rolling, then manufacturability and productivity are improved, but high-temperature oxidation resistance and shape stability deteriorate
Solution Approach 1:
The patent changes the chemical composition parameters by limiting Cr to 10.0-16.0% (lower than conventional levels) and Al to 2.0-4.0%, while introducing specific ranges for Ti (0.01-0.30%), Zr (0.01-0.20%), Hf (0.01-0.20%), and REM (0.01-0.20%). This parameter optimization enables continuous tandem rolling while maintaining high-temperature oxidation resistance through the synergistic effect of these elements in the specified ranges.
Solution Approach 2:
The patent creates a composite alloy system by combining Fe-Cr-Al base steel with multiple microalloying elements (Ti, Zr, Hf, REM) in specific proportions. This composite composition achieves both improved toughness for continuous rolling and maintained oxidation resistance, as each element contributes specific properties that complement each other in the multi-element system.
2Reliability
If conventional cold rolling processes are used to ensure high-temperature oxidation resistance and shape stability, then product quality is maintained, but manufacturing costs increase
Solution Approach 1:
The patent optimizes composition parameters (Cr: 10.0-16.0%, Al: 2.0-4.0%, Ti: 0.01-0.30%, Zr: 0.01-0.20%, Hf: 0.01-0.20%, REM: 0.01-0.20%) to enable the use of continuous tandem rolling processes, which are more productive and cost-effective than conventional cold rolling. The specific composition ranges ensure that oxidation resistance and shape stability are maintained even with the reduced Cr and Al content, making the lower-cost manufacturing process viable.
3Reliability
If Fe-Cr-Al-type stainless steel is used for high-temperature oxidation resistance, then oxidation resistance is improved, but toughness of intermediate materials deteriorates
Solution Approach 1:
The patent optimizes the composition parameters by controlling Cr content (10.0-16.0%) and Al content (2.0-4.0%) within specific ranges, and by adding microalloying elements Ti (0.01-0.30%), Zr (0.01-0.20%), Hf (0.01-0.20%), and REM (0.01-0.20%). This parameter optimization improves toughness while maintaining high-temperature oxidation resistance.
Solution Approach 2:
The patent creates a composite alloy system combining Fe-Cr-Al base steel with multiple microalloying elements (Ti, Zr, Hf, REM) in specific proportions. This composite composition achieves both improved toughness for continuous rolling and maintained oxidation resistance, as each element contributes specific properties that complement each other in the multi-element system.
Data Source
AI summary
A stainless steel foil having a chemical composition comprising, by mass %, C: 0.015% or less, Si: 0.50% or less, Mn: 0.50% or less, P: 0.040% or less, S: 0.010% or less, Cr: 10.0% or more and less than 16.0%, Al: 2.5 to 4.5%, N: 0.015% or less, Ni: 0.05 to 0.50%, Cu: 0.01 to 0.10%, Mo: 0.01 to 0.15%, at least one selected from the group consisting of Ti: 0.01 to 0.30%, Zr: 0.01 to 0.20%, Hf: 0.01 to 0.20%, and REM: 0.01 to 0.20%, where Ti+Zr+Hf+2REM≥0.06 and 0.30≥Ti+Zr+Hf are satisfied.