Alloy Brake Disc Heat Treatment for Machinability and Cooling
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Solution Overview
Problem
Gray cast iron brake discs suffer from poor machinability due to carbide production at eutectic cell boundaries, leading to increased surface roughness and reduced operability, necessitating a method to enhance heat dissipation and surface hardness.
Innovation Solution
A method involving mixing gray cast iron with Fe—Cr ferroalloy, followed by pearlitzation heat treatment and nitriding heat treatment under specific conditions to improve microstructure and surface properties, resulting in a lightweight brake disc with enhanced heat dissipation, tensile strength, and surface hardness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If gray cast iron is used for brake disc manufacturing, then heat dissipation performance is improved, but machinability deteriorates due to carbide production at eutectic cell boundaries
Solution Approach 1:
The patent applies parameter changes by modifying the chemical composition parameters of the cast iron (adding specific elements like Cr, Mo, Ni within defined ranges) and changing the heat treatment parameters (temperature, time, atmosphere) to transform the microstructure and reduce carbide formation, thereby improving machinability while maintaining heat dissipation properties
Solution Approach 2:
The patent creates a composite material system by combining gray cast iron with specific alloying elements (Cr: 0.5-2.0%, Mo: 0.1-0.5%, Ni: 0.1-0.5%) to form a modified cast iron composition that maintains the heat dissipation advantages of gray cast iron while suppressing harmful carbide formation through elemental interactions
2Device complexity
If traditional casting and machining methods are used, then manufacturing process is simple, but surface roughness increases and operability decreases
Solution Approach 1:
The patent applies preliminary action by performing heat treatment (normalizing at 850-950°C for 2-8 hours followed by tempering at 150-250°C for 2-8 hours) before the final machining operation. This preliminary heat treatment modifies the microstructure to reduce carbide formation and improve machinability, enabling better surface finish without requiring complex post-processing
Solution Approach 2:
The patent changes the thermal parameters (heating temperature, holding time, cooling rate) to control the microstructural evolution during heat treatment, transforming the as-cast microstructure into a more machinable state that reduces surface roughness while maintaining dimensional stability
3Ease of manufacture
If carbide formation is reduced to improve machinability, then surface roughness decreases, but heat dissipation performance may be affected
Solution Approach 1:
The patent carefully balances the chemical composition parameters to suppress carbide formation (through controlled addition of Cr, Mo, Ni) while maintaining the graphite flake structure that provides heat dissipation. The heat treatment parameters are also optimized to transform the matrix structure without compromising the graphite distribution, thereby simultaneously improving machinability and preserving heat dissipation performance
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 achieves a brake disc with improved tensile strength and surface hardness, increasing the brake disc's performance and operability while being eco-friendly, establishing a stable and reliable mass production system for lightweight automotive materials.
Implementation Method 1
mixing gray cast iron and Fe—Cr ferroalloy with each other to produce a mixture, melting and solidifying the mixture to cast an alloy
Implementation Method 2
heat-treating the alloy cast in the first step to pearlitize a microstructure of the alloy
Implementation Method 3
performing nitriding heat treatment of the alloy heat-treated in the second step
Data Source
AI summary
Disclosed is a method for manufacturing a lightweight brake disc with maximized heat dissipation ability. The method includes a first step of mixing gray cast iron and Fe—Cr ferroalloy with each other to produce a mixture, melting and solidifying the mixture to cast an alloy; a second step of heat-treating the alloy cast in the first step to pearlitize a microstructure of the alloy; and a third step of performing nitriding heat treatment of the alloy heat-treated in the second step.