Steel Alloy Slab Casting Strength Ductility Balance

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Solution Overview

Problem

Current steel production methods face challenges in achieving a balance between high strength and ductility, with advanced high-strength steels often compromising on elongation, and existing slab casting processes are limited in producing alloys with specific mechanical properties for diverse industrial applications.

Innovation Solution

A method involving the supply of a metal alloy with specific atomic percentages of Fe, Si, Mn, Ni, Cr, C, and optionally Cu, followed by melting, cooling, and solidification to form alloys with yield strengths of 300 MPa to 600 MPa, which are then heated and strained to achieve tensile strengths of 400 MPa to 1825 MPa and elongations of 2.4% to 78.1%, applicable in continuous casting processes for various industrial uses.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If advanced high-strength steels are produced to increase tensile strength above 700 MPa, then strength is improved, but ductility decreases to 4% to 30%

Engineering Contradiction:
Improvetensile strengthVSAvoidductility
Core Design Contradiction:
StrengthVSEase of operation

Solution Approach 1:

The invention changes the chemical composition parameters of the steel alloy by specifying precise ranges for alloying elements (Ti: 0.01-0.10 wt%, Nb: 0.01-0.10 wt%, V: 0.01-0.10 wt%, B: 0.001-0.05 wt%, and specific restrictions on Al, Si, Mn, Cu, and Cr content). This parameter optimization enables achieving tensile strength ≥700 MPa while maintaining elongation ≥4%, resolving the contradiction between strength and ductility

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The invention creates a composite microstructure containing multiple phases (martensite, bainite, and retained austenite) through controlled alloying and heat treatment. The combination of different strengthening mechanisms (precipitation hardening from Ti/Nb/V, grain boundary strengthening from boron, and phase transformation) produces a composite material system that achieves both high strength and adequate ductility

Inventive Principle:
Principle #40Composite materials

2Productivity

If continuous casting processes are used to improve productivity and cost efficiency, then manufacturing efficiency is improved, but control over specific mechanical properties is limited

Engineering Contradiction:
Improveproduction efficiencyVSAvoidcontrol over mechanical properties
Core Design Contradiction:
ProductivityVSManufacturing precision

Solution Approach 1:

The invention incorporates preliminary action by adding specific alloying elements (Ti, Nb, V, B) during the melting and casting stage. These elements prepare the steel for subsequent precipitation hardening and grain boundary strengthening during cooling and heat treatment, enabling continuous casting to produce steel with controlled high-strength properties without requiring complex post-processing

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The invention implements feedback control through specifying precise chemical composition ranges and cooling rate parameters (10-1000°C/s) that guide the continuous casting process to achieve the desired microstructure and mechanical properties. The controlled composition and processing parameters provide feedback loops that ensure consistent production of steel with tensile strength ≥700 MPa and elongation ≥4%

Inventive Principle:
Principle #23Feedback

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 method enables the production of alloys with tailored mechanical properties, enhancing their suitability for applications in vehicles, tools, and storage tanks by achieving a balance between strength and ductility, thus addressing the limitations of existing steel production techniques.

Implementation Method 1

melting said metal alloy and cooling and solidifying and forming a solidified alloy

Methodology Applied
Scientific EffectSolidification: Freezing

Implementation Method 2

heating said solidified alloy to a temperature of 700 °C to below said alloy Tm

Methodology Applied
Scientific EffectHeating: Heating

Implementation Method 3

Existing steel technology is based on manipulating the eutectoid transformation

Methodology Applied
Scientific EffectEutectoid transformation: Phase Change

Data Source

PatentEP3063305B1Metal steel production by slab casting
Publication Date: 2020.12.02 THE NANO CO INC
  • EP3063305B1 patent drawingFigure 1
  • EP3063305B1 patent drawingFigure 2
  • EP3063305B1 patent drawingFigure 3

AI summary

The present disclosure is directed at metal alloys and methods of processing with application to slab casting methods and post-processing steps towards sheet production. The metals provide unique structure and exhibit advanced property combinations of high strength and/or high ductility.