Advanced High-Strength Steel Alloy Composition and Thermo-Mechanical Processing
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Solution Overview
Problem
Current Advanced High-Strength Steels (AHSS) face challenges in achieving a balance between high strength and ductility, requiring complex control of alloy composition and processing conditions, which limits their application in various industries.
Innovation Solution
Development of metal alloys with specific compositions of Fe, B, Si, Mn, and optional elements like Ni, Cr, Cu, Ti, and C, undergoing elevated temperature treatment and cold deformation to produce metallic sheets with refined grain sizes and boride precipitations, resulting in high strength and ductility.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the strength level of steel is increased to produce Advanced High-Strength Steels (AHSS), then tensile strength is improved (greater than 700 MPa), but ductility deteriorates (tensile elongation decreases to 4% to 50%)
Solution Approach 1:
The patent applies parameter changes by precisely controlling alloy composition parameters (specific ratios of Mn, Si, B, and other elements) and processing parameters (cooling rates, heating temperatures, deformation conditions) to achieve a optimal balance between strength and ductility. The composition ranges and processing conditions are carefully optimized to produce the desired microstructure that simultaneously provides high tensile strength (>700 MPa) and acceptable ductility (4%-50% elongation).
Solution Approach 2:
The patent creates a composite microstructure consisting of multiple phases (martensite, ferrite, austenite, and cementite) within the steel alloy. This multiphase composite structure allows different phases to contribute different properties: martensite provides high strength, while ferrite and austenite contribute to ductility. The controlled distribution and morphology of these phases enable the steel to achieve both high strength and improved formability.
2Strength
If complex control of alloy composition and processing conditions is implemented to achieve desired microstructures, then tensile strength and formability are improved, but device complexity increases
Solution Approach 1:
The patent applies preliminary action by pre-designing the alloy composition within specific ranges and pre-planning the thermo-mechanical processing route before production. The alloy formulation is optimized in advance to be more responsive to specific processing conditions, and the processing parameters are predetermined to achieve the desired microstructure. This reduces the need for complex real-time adjustments during manufacturing.
Solution Approach 2:
The patent systematically varies and optimizes multiple parameters including alloy composition (Mn: 1.0-19.0 at%, Si: 0.5-12.0 at%, B: 0.50-8.0 at%, etc.), heating temperatures, cooling rates, and deformation conditions. By establishing clear parameter ranges and their interrelationships, the patent provides a structured approach that simplifies control while achieving complex microstructural outcomes.
3Strength
If multiple cycles of elevated temperature treatment and cold deformation are applied, then grain size is refined and strength is improved, but manufacturing time increases
Solution Approach 1:
The patent employs periodic action through multiple cycles of elevated temperature treatment followed by cold deformation. Each cycle consists of heating to a specific temperature range, holding for a controlled duration, then applying cold deformation. These periodic cycles progressively refine the grain structure and strengthen the material. The number and duration of cycles are optimized to achieve the desired strength level while minimizing total processing time.
Data Source
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AI summary
This disclosure deals with a class of metal alloys with advanced property combinations applicable to metallic sheet production. More specifically, the present application identifies the formation of metal alloys of relatively high strength and ductility and the use of one or more cycles of elevated temperature treatment and cold deformation to produce metallic sheet at reduced thickness with relatively high strength and ductility.