Steel Sheet Partial Cold Deformation for Homogeneous Thickness

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Solution Overview

Problem

Existing methods for manufacturing flexible rolled blanks in steel products cannot create areas with varying mechanical and physical properties along the length, limiting their application in components requiring localized strength and ductility, as they rely solely on thickness variations and uniform mechanical properties.

Innovation Solution

A multi-step rolling and annealing process involving flexible rolling, annealing, and reverse flexible rolling to achieve a homogeneously thick steel sheet with areas of different mechanical properties, allowing for specific variations in yield strength, tensile strength, and elongation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Shape

If flexible rolling is used to create variable thickness steel products, then thickness variation is achieved, but uniform mechanical properties are maintained throughout the product

Engineering Contradiction:

Improvethickness variationVSAvoiduniform mechanical properties

Core Design Contradiction:

ShapeVSStrength

Solution Approach 1:

The steel strip is divided into multiple zones along its length, each subjected to different rolling reduction ratios. This segmentation allows different thickness reductions in different zones, creating variable thickness while enabling subsequent differential mechanical properties through selective annealing or cold rolling in specific zones.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Different mechanical properties are introduced into specific local zones of the steel strip through controlled rolling and annealing processes. By applying different processing parameters to different sections, the material achieves locally optimized properties such as varying tensile strength, elongation, or hardness in specific areas while maintaining homogeneous thickness.

Inventive Principle:

Principle #3Local quality

2Strength

If thickness is varied to adapt to load requirements, then structural optimization is achieved, but homogeneous thickness is lost complicating handling and processing

Engineering Contradiction:

Improveload adaptationVSAvoidhandling and processing

Core Design Contradiction:

StrengthVSEase of operation

Solution Approach 1:

Instead of varying thickness to achieve different mechanical properties, the invention inverts the approach by maintaining homogeneous thickness throughout the strip while creating mechanical property variations through controlled plastic deformation and annealing in specific zones. This allows load adaptation through material properties rather than geometric variation, simplifying handling and processing.

Inventive Principle:

Principle #13The other way round (Inversion)

3Strength

If multi-material design is used to fulfill locally varying requirements, then performance is optimized, but device complexity and cost increase

Engineering Contradiction:

Improvelocally varying requirementsVSAvoidmanufacturing complexity

Core Design Contradiction:

StrengthVSDevice complexity

Solution Approach 1:

The invention achieves locally varying mechanical properties by changing processing parameters (rolling reduction ratio, annealing temperature, deformation degree) rather than changing material composition. This allows different zones of the same steel strip to exhibit different properties such as tensile strength or elongation, fulfilling locally varying requirements while maintaining manufacturing simplicity and cost-effectiveness.

Inventive Principle:

Principle #35Parameter changes

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

This process enables the creation of steel products with areas of high strength and high ductility, ensuring easier handling and processing, reduced failure rates, and eliminating the need for costly heat treatments, while maintaining a constant thickness, enhancing the material's formability and corrosion resistance.

Implementation Method 1

a) annealing the deformed steel strip

Methodology Applied

Scientific EffectAnnealing: Annealing

Implementation Method 2

cold deformation of steel by utilizing a multi-step rolling and annealing process

Methodology Applied

Scientific EffectPlasticity: Plasticity

Data Source

PatentUS12110571B2Method for partial cold deformation of steel with homogeneous thickness

Publication Date: 2024.10.08 OUTOKUMPU OY

AI summary

The invention relates to a method for partial hardening of a steel sheet by cold deformation, where the partial hardening of a steel is done by a cold deformation with a multi-step rolling and annealing process and in order to have a steel sheet with a homogeneous thickness steel sheet is used with at least two areas having different values in mechanical and/or physical properties in longitudinal direction of the material.