Lean Austenitic Stainless Steel Composition for Cost Reduction
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Solution Overview
Problem
There is a need for a cost-effective austenitic stainless steel alloy with improved high-temperature properties and comparable corrosion resistance and formability to higher nickel and molybdenum alloys, while reducing the use of expensive nickel and molybdenum.
Innovation Solution
The development of a stabilized austenitic stainless steel composition using controlled levels of carbide-forming elements such as manganese, copper, and nitrogen to replace nickel and molybdenum, optionally incorporating tungsten and cobalt to achieve similar properties at lower raw material costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If nickel and molybdenum are used to maintain austenitic structure and corrosion resistance, then corrosion resistance and formability are improved, but material cost increases
Solution Approach 1:
The patent replaces expensive nickel and molybdenum with cheaper alternative elements (manganese, copper, nitrogen, and carbide-forming elements) to achieve the same functional properties at lower cost. This substitution principle directly addresses the contradiction by using economically cheaper materials that provide comparable or superior performance.
Solution Approach 2:
The patent modifies the chemical composition parameters of the stainless steel by controlling the levels of carbide-forming elements and alternative alloying elements. By adjusting these compositional parameters, the patent achieves improved high-temperature properties and maintained corrosion resistance while reducing dependence on expensive nickel and molybdenum.
2Quantity of substance
If nickel and molybdenum levels are reduced to lower cost, then material cost decreases, but corrosion resistance and formability may deteriorate
Solution Approach 1:
The patent employs cheaper alternative elements (manganese, copper, nitrogen) to replace expensive nickel and molybdenum, maintaining corrosion resistance and formability through optimized combinations of these substitute elements rather than direct reduction without replacement.
Solution Approach 2:
The patent creates a composite alloy system combining multiple alternative elements (manganese, copper, nitrogen, and carbide-forming elements) to achieve the functional properties previously provided by nickel and molybdenum. This composite approach ensures that corrosion resistance and formability are maintained through synergistic effects of the alternative element combination.
3Ease of operation
If standard austenitic stainless steel composition is used, then good formability is achieved, but high-temperature properties are insufficient
Solution Approach 1:
The patent modifies the chemical composition parameters by adding controlled levels of carbide-forming elements (titanium, niobium, vanadium, tantalum, or zirconium) to the austenitic stainless steel. These compositional changes enhance high-temperature properties through carbide formation and precipitation hardening while preserving the austenitic structure and formability at room temperature.
Solution Approach 2:
The patent develops a composite austenitic stainless steel system that integrates carbide-forming elements with traditional austenite-stabilizing elements (manganese, copper, nitrogen). This composite structure provides dual functionality: good formability at room temperature from the austenitic matrix and improved high-temperature properties from the carbide precipitates and strengthened matrix.
Data Source
AI summary
An austenitic stainless steel composition including relatively low nickel and molybdenum levels, and exhibiting corrosion resistance, resistance to elevated temperature deformation, and formability properties comparable to certain alloys including higher nickel and molybdenum levels. Embodiments of the austenitic stainless steel include, in weight %, up to 0.20 C, 2.0 to 9.0 Mn, up to 2.0 Si, 16.0 to 23.0 Cr, 1.0 to 7.0 Ni, up to 3.0 Mo, up to 3.0 Cu, 0.05 to 0.35 N, up to 4.0 W, (7.5(C))≦(Nb+Ti+V+Ta+Zr)≦1.5, up to 0.01 B, up to 1.0 Co, iron and impurities. Additionally, embodiments of the steel may include 0.5≦(Mo+W/2)≦5.0 and/or 1.0≦(Ni+Co)≦8.0.