Steel Piston Ring Composition for Wear and Breakage Resistance

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Solution Overview

Problem

Piston rings and cylinder sleeves made from cast iron are prone to wear and breakage under high mechanical and dynamic loads, leading to engine inefficiencies and increased maintenance costs, while steel alternatives face challenges in production and cost due to high melting temperatures and equipment limitations.

Innovation Solution

A steel material composition with a high silicon content, incorporating boron as a carbide former, is developed for improved wear resistance, allowing for production using existing cast iron equipment and processes, with specific elemental proportions to enhance mechanical properties and reduce tool wear.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If cast iron materials are used for piston rings and cylinder sleeves, then wear resistance is improved, but susceptibility to breakage increases under high mechanical loads

Engineering Contradiction:
Improvewear resistanceVSAvoidresistance to breakage
Core Design Contradiction:
ReliabilityVSStrength

Solution Approach 1:

The patent changes the chemical composition parameters of the iron material by strictly limiting carbon content to ≤2.08% (classifying it as steel rather than cast iron), controlling silicon content at 2.0-10.0%, and adding specific alloying elements. This parameter change transforms the material from brittle cast iron to a stronger steel alloy that resists both wear and breakage under high mechanical loads

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The patent creates a composite material system by combining multiple alloying elements (boron, nickel, chromium, molybdenum, vanadium, tungsten, niobium, titanium) with the iron base and controlled carbon-silicon content. This composite approach produces a material that integrates the wear resistance traditionally associated with cast iron while achieving the strength and ductility of steel

Inventive Principle:
Principle #40Composite materials

2Strength

If steel materials are used instead of cast iron, then strength and ductility are improved, but melting temperature increases making production more costly

Engineering Contradiction:
Improvestrength and ductilityVSAvoidmelting temperature and production cost
Core Design Contradiction:
StrengthVSEase of manufacture

Solution Approach 1:

The patent carefully controls the carbon content parameter at ≤2.08% and silicon content at 2.0-10.0%, which influences the material's melting characteristics. By optimizing this compositional parameter range and adding specific alloying elements, the patent achieves steel-level strength and ductility while managing the melting temperature to remain compatible with existing production equipment and cost structures

Inventive Principle:
Principle #35Parameter changes

3Strength

If higher carbon content is used to improve strength, then mechanical strength increases, but the material becomes more brittle and susceptible to breakage

Engineering Contradiction:
Improvemechanical strengthVSAvoidmicrostructure stability and brittleness
Core Design Contradiction:
StrengthVSStability of the object's composition

Solution Approach 1:

The patent implements a precise parameter change by capping carbon content at ≤2.08% (the boundary between steel and cast iron) while strategically adding alloying elements like boron (0.03-2.0%), nickel (0.5-4.0%), chromium (0.1-3.0%), and others. This compositional parameter optimization achieves high mechanical strength while preventing the formation of free graphite that would disrupt the microstructure and cause brittleness

Inventive Principle:
Principle #35Parameter changes

Data Source

PatentUS8882937B2Steel material composition for producing piston rings and cylinder sleeves
Publication Date: 2014.11.11 FEDERAL MOGUL BURSCHEID GMBH

AI summary

The invention relates to a steel material composition, in particular for producing piston rings and cylinder sleeves, containing the following elements in the given fractions in relation to 100% by weight of the steel material: 0.03-2.0% by weight B, 0.5-1.2% by weight C, 70.1-97.3% by weight Fe, 0.1-3.0% by weight Mn and 2.0-10.0% by weight Si. Said composition can be produced by melting the starting materials and casting the melt in a pre-fabricated mold.