Gray Cast Iron Composition for Wear-Resistant Brake Discs

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Solution Overview

Problem

Existing gray cast iron brake discs suffer from wear, mechanical stress, thermal stress, and corrosion issues, which affect their durability and performance, particularly in high-performance vehicles, without achieving simultaneous improvements in wear, mechanical, and corrosion resistance.

Innovation Solution

A specific alloy composition of gray cast iron comprising carbon, silicon, vanadium, manganese, nickel, chromium, molybdenum, copper, sulfur, phosphorous, tin, and titanium, with controlled percentages, combined with a pearlitic or fine lamellar ferrous matrix, enhances wear resistance without compromising mechanical and corrosion resistance.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Duration of action of stationary object

If the wear resistance of gray cast iron brake discs is increased, then the duration of the disc is improved, but the mechanical and thermal resistance may deteriorate due to high intensity stresses

Engineering Contradiction:
Improveduration of brake discVSAvoidmechanical and thermal resistance
Core Design Contradiction:
Duration of action of stationary objectVSStrength

Solution Approach 1:

The patent applies parameter changes by precisely controlling the chemical composition parameters of the cast iron alloy. Specific ranges are defined for carbon (3.5-4.0%), silicon (1.5-2.5%), phosphorus (0.05-0.20%), sulfur (0.05-0.15%), and other elements to optimize the microstructure and achieve simultaneous improvements in wear resistance, mechanical strength, and thermal resistance without compromising any single property.

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The patent creates a composite microstructure within the gray cast iron by combining graphite flakes with a controlled matrix structure. The specific alloy composition promotes a matrix that simultaneously provides wear resistance and maintains mechanical-thermal resistance under high intensity stresses, effectively creating a composite material system at the microstructural level.

Inventive Principle:
Principle #40Composite materials

2Duration of action of stationary object

If the wear resistance of gray cast iron brake discs is increased, then the duration of the disc is improved, but the corrosion resistance may deteriorate

Engineering Contradiction:
Improveduration of brake discVSAvoidcorrosion resistance
Core Design Contradiction:
Duration of action of stationary objectVSReliability

Solution Approach 1:

The patent addresses this contradiction by carefully adjusting the chemical composition parameters, particularly controlling phosphorus content (0.05-0.20%) and sulfur content (0.05-0.15%) while optimizing carbon and silicon levels. This balanced compositional approach ensures that wear resistance is enhanced through appropriate graphite formation while corrosion resistance is maintained by preventing excessive formation of brittle or corrosive phases.

Inventive Principle:
Principle #35Parameter changes

3Object-generated harmful factors

If high wear resistance is achieved in gray cast iron, then metal powder release into the environment is reduced, but the complexity of alloy composition increases

Engineering Contradiction:
Improvemetal powder releaseVSAvoidalloy composition complexity
Core Design Contradiction:
Object-generated harmful factorsVSDevice complexity

Solution Approach 1:

The patent manages alloy composition complexity by defining specific, optimized ranges for each element rather than using excessive amounts of multiple additives. The composition focuses on achieving the desired wear resistance through controlled parameters of essential elements (carbon, silicon, phosphorus, sulfur) with minimal additions of other elements, thereby reducing metal powder release while keeping the alloy formulation practical and not overly complex.

Inventive Principle:
Principle #35Parameter changes

Data Source

PatentEP4004249B1Cast iron, in particular for components of disc brakes
Publication Date: 2026.04.01 FRENI BREMBO SPA

AI summary

The invention consists of a gray cast iron comprising carbon, silicon, vanadium, manganese, nickel, chromium, molybdenum, copper, sulfur, phosphorous, tin and titanium, wherein: the percentage by weight of carbon is from 3.70 to 3.90%; the percentage by weight of silicon is from 1.30 to 2.10%; the percentage by weight of vanadium is from 0.10 to 0.15%; the percentage by weight of manganese is from 0.60 to 0.90%; the percentage by weight of nickel is from 0.05 to 0.50%; the percentage by weight of chromium is from 0.20 to 0.35%; the percentage by weight of molybdenum is no more than 0.10%; the percentage by weight of copper is no more than 0.35%; the percentage by weight of sulfur is less than 0.10%; the percentage by weight of phosphorous is less than 0.10%; the percentage by weight of tin is less than 0.10%; the percentage by weight of titanium is no more than 0.01%; the remainder by weight being iron.