Maraging Stainless Steel Multiphase Strengthening Corrosion Trade-off
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current ultrahigh-strength stainless steels face challenges in achieving a balance between strength, toughness, and corrosion resistance, with high Co content increasing material costs and reducing corrosion resistance, and complex processing methods complicating control over carbide size and distribution.
Innovation Solution
A novel ultrahigh-strength maraging stainless steel with a multiphase strengthening structure, featuring a martensitic lath and amorphous layer, optimized alloying elements, and thermomechanical treatments, which reduces Co content, enhances nanoprecipitate formation, and improves corrosion resistance through synergistic strengthening and amorphous phase promotion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the content of Co is increased to improve mechanical properties, then strength is improved, but corrosion resistance deteriorates
Solution Approach 1:
The patent optimizes the Co content to a specific range (3.0-7.0 wt%) rather than using high amounts, and combines it with controlled C content (0.02 wt% or less) and specific alloying elements (Ni: 6.0-10.0%, Cr: 11.0-17.0%, Mo: 3.0-7.0%) to achieve the desired balance between strength and corrosion resistance through parameter optimization
Solution Approach 2:
The patent creates a multiphase composite structure including martensitic lath, amorphous layer at lath boundaries, and various nanoprecipitates (Ni3(Ti, Mo), Mo-enriched R′ phase, α′-Cr) that work synergistically to provide both strength and corrosion resistance, replacing the reliance on high Co content
2Strength
If carbon strengthening is used to achieve high strength, then strength is improved, but corrosion resistance and toughness deteriorate
Solution Approach 1:
The patent extracts and removes carbon from the strengthening mechanism by limiting C content to 0.02 wt% or less, and replaces carbon strengthening with nanoprecipitate strengthening (Ni3(Ti, Mo), Mo-enriched R′ phase, α′-Cr) and amorphous phase formation, thereby eliminating the harmful effects of carbon while maintaining high strength
Solution Approach 2:
The patent changes the strengthening mechanism from carbon-based to nanoprecipitate-based by controlling C content to 0.02 wt% or less and optimizing the content of alloying elements (Ti: 0.3-2.0%, Mo: 3.0-7.0%, Ni: 6.0-10.0%) to promote the formation of strengthening nanoprecipitates that provide strength without compromising corrosion resistance and toughness
3Strength
If complex processing methods are used to achieve ultrahigh strength, then strength is improved, but manufacturing complexity and control difficulty increase
Solution Approach 1:
The patent merges multiple processing steps into a simplified integrated thermomechanical treatment process that combines hot rolling with cogging, cold rolling, and heat treatment (quenching at 1,050-1,200°C followed by aging at 450-600°C) to achieve ultrahigh strength with a unified process rather than separate complex steps
Solution Approach 2:
The patent optimizes specific processing parameters including hot rolling temperature (1,050-1,200°C), quenching temperature (450-600°C), and aging temperature (450-600°C) to control the formation of the multiphase structure and achieve ultrahigh strength through parameter optimization rather than complex processing sequences
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The solution achieves high strength, toughness, and corrosion resistance with reduced material costs and simplified processing, resulting in a stainless steel with tensile strength up to 2,700 MPa and elongation of 10% while maintaining excellent corrosion resistance.
Implementation Method 1
The main reason for the maraging stainless steel to achieve ultrahigh strength is the superposition of martensitic transformation strengthening and precipitation strengthening
Implementation Method 2
the martensitic lath includes various nano-scale precipitates in dispersed distribution. An ultrahigh strength is achieved by synergistic strengthening of the various nanoprecipitates
Implementation Method 3
the lath boundary modified by the amorphous layer not only promotes dislocation multiplication but also absorbs the dislocations, thereby achieving high plasticity and great work hardening capacity
Implementation Method 4
the presence of reverted austenite also contributes to the plasticity and toughness of the material
Implementation Method 5
its corrosion resistance is attributed to a passive film formed on the surface thereof via addition of Cr and Mo
Data Source
AI summary
Disclosed is an ultrahigh-strength maraging stainless steel with multiphase strengthening and a preparation method thereof. The stainless steel has a composition in mass percentage as follows: 1.0-5.0% of Co, 6.0-10.0% of Ni, 11.0-17.0% of Cr, 0.3-2.0% of Ti, 3.0-7.0% of Mo, 0.08-1.0% of Mn, 0.08-0.5% of Si, 0.02% or less of C, 0.003% or less of P, 0.003% or less of S, and Fe as a balance.