Microalloyed Steel Strip for Lightweight Flexible Edge Sealing

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Solution Overview

Problem

Existing metal strips for decorative or sealing strips in the automotive sector are heavy and require significant material thickness due to high tensile strength needs, leading to excessive weight and sealing material usage, and are costly when adhesive-coated, while existing alternatives do not meet flexibility and compressibility requirements for varying opening sizes.

Innovation Solution

A metal strip made of micro-alloyed steel with a thickness of 0.4 mm or less, featuring micro-alloyed steel with vanadium, niobium, and/or titanium additions, and designed with specific slot configurations for enhanced flexibility and tensile strength, allowing for reduced weight and sealing material usage.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If metal strip thickness is increased to achieve required tensile strength, then strength is improved, but weight increases

Engineering Contradiction:
Improvetensile strengthVSAvoidweight
Core Design Contradiction:
StrengthVSWeight of moving object

Solution Approach 1:

The patent changes the material parameters by using micro-alloyed steel with specific alloying elements (Ti: 0.02-0.06%, Nb: 0.02-0.06%, V: 0.02-0.06%, C: 0.17-0.30%, Si: 0.93-1.50%, Mn: 1.00-2.00%) to achieve high tensile strength at reduced thickness. This allows the metal strip to maintain required strength while reducing weight through thinner cross-section

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The patent creates a composite microstructure within the steel by controlling phase composition (martensite, bainite, and retained austenite) through micro-alloying and heat treatment. This composite material structure provides high strength-to-weight ratio, enabling thin strips to achieve required tensile strength without increasing weight

Inventive Principle:
Principle #40Composite materials

2Weight of moving object

If metal strip thickness is reduced to decrease weight, then weight is reduced, but tensile strength decreases

Engineering Contradiction:
ImproveweightVSAvoidtensile strength
Core Design Contradiction:
Weight of moving objectVSStrength

Solution Approach 1:

The patent compensates for reduced thickness by optimizing material parameters including carbon content (0.17-0.30%) for strength, silicon (0.93-1.50%) for aging resistance, and micro-alloying elements (Ti, Nb, V at 0.02-0.06% each) for precipitation hardening. This parameter optimization enables thin strips (3-8mm) to achieve required tensile strength

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The patent creates local quality variations through the micro-alloying strategy where precipitates of carbides, nitrides, and carbonitrides form locally to provide reinforcement. The controlled distribution of alloying elements creates local strengthening zones that compensate for overall thickness reduction

Inventive Principle:
Principle #3Local quality

3Loss of substance

If material thickness is reduced to save material and weight, then material usage is reduced, but flexibility and compressibility may be affected

Engineering Contradiction:
Improvematerial usageVSAvoidflexibility and compressibility
Core Design Contradiction:
Loss of substanceVSAdaptability or versatility

Solution Approach 1:

The patent optimizes the balance between thickness and material properties by selecting specific carbon (0.17-0.30%) and silicon (0.93-1.50%) content ranges. This parameter optimization ensures that thin strips (3-8mm) maintain adequate ductility and flexibility for forming operations while reducing material consumption

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The patent enables dynamic adaptability through the metal strip's ability to be formed into various profiles (U-shaped, channel-shaped, angle-shaped) and its controlled elasticity. The strip can be compressed and expanded in the longitudinal direction to accommodate different opening sizes, providing versatility despite reduced thickness

Inventive Principle:
Principle #15Dynamics

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 provides high tensile strength with reduced weight and material usage, enabling efficient attachment and minimal energy consumption during cutting while maintaining flexibility and compressibility, thus optimizing manufacturing efficiency and cost-effectiveness.

Implementation Method 1

Microalloyed steel, also known as HSLA steel, is steel to which very small amounts of vanadium and/or niobium and/or titanium have been added

Methodology Applied
Scientific EffectPrecipitation hardening:

Implementation Method 2

By using micro-alloyed steel, high tensile strength can be achieved with a reduced material thickness

Methodology Applied
Scientific EffectGrain refinement:

Implementation Method 3

the metal strip consists of hot- or cold-formed steel

Methodology Applied
Scientific EffectPlastic deformation: Plasticity

Implementation Method 4

Cut or punched slits can be widened by rolling

Methodology Applied
Scientific EffectCompression: Compression

Data Source

PatentEP3924198B1Metal strip
Publication Date: 2025.12.31 BFC FAHRZEUGTEILE GMBH
  • EP3924198B1 patent drawingFigure 1~2
  • EP3924198B1 patent drawingFigure 3~4
  • EP3924198B1 patent drawingFigure 5

AI summary

The invention relates to a metal strip as an insert for decorative or sealing strips or as an edge protection, in particular for motor vehicles or electrical enclosures, said strip being provided with cut and/or punched perforations, wherein the metal strip consists of microalloyed steel or multi-phase steel.