Gray Cast Iron Brake Disk Nitriding Process
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Solution Overview
Problem
Conventional methods for manufacturing gray cast iron brake disks are time-consuming and costly due to stress-relief annealing and oxynitriding processes, resulting in non-uniform properties and corrosion issues.
Innovation Solution
A method involving casting gray cast iron with specific carbon and silicon content, machining, nitriding at 540° C to 580° C for 50-70 minutes, and painting to form a 4-6 μm nitride layer without stress-relief annealing or oxidation, reducing processing time and maintaining low disk thickness variation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If stress-relief annealing and oxynitriding are performed using conventional methods, then corrosion resistance is improved, but processing time and cost increase significantly
Solution Approach 1:
The patent changes the chemical composition parameters of the cast iron by controlling carbon content (3.0-3.8 wt%) and silicon content (2.0-3.5 wt%), which enables the material to achieve adequate corrosion resistance without requiring the conventional stress-relief annealing and oxynitriding processes, thereby reducing processing time
Solution Approach 2:
The patent extracts and eliminates the stress-relief annealing and oxynitriding steps from the conventional manufacturing process, retaining only the essential casting and machining operations, which significantly reduces processing time while maintaining adequate corrosion resistance through controlled material composition
2Reliability
If stress-relief annealing and oxynitriding are performed using conventional methods, then surface layer properties are improved, but manufacturing cost increases
Solution Approach 1:
The patent modifies the chemical composition parameters of the cast iron (carbon: 3.0-3.8 wt%, silicon: 2.0-3.5 wt%) to achieve uniform surface properties directly during casting, eliminating the need for costly post-casting heat treatment processes like oxynitriding
3Reliability
If conventional oxynitriding is performed, then corrosion resistance is enhanced, but processing complexity increases
Solution Approach 1:
The patent removes the complex oxynitriding process step from the manufacturing sequence, simplifying the overall process while achieving adequate corrosion resistance through controlled cast iron composition (carbon: 3.0-3.8 wt%, silicon: 2.0-3.5 wt%)
Solution Approach 2:
The patent changes the material composition parameters to inherently provide corrosion resistance, eliminating the need for additional chemical heat treatment processes and thereby reducing process complexity
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 approach reduces processing time and cost, ensures equivalent corrosion resistance, and maintains low disk thickness variation while enhancing NVH performance without stress-relief annealing.
Implementation Method 1
nitriding the disk body by exposing the machined surface to a temperature in the range of 540° C. to 580° C. for 50 min to 70 min
Implementation Method 2
a diffusion layer having a thickness of 0.2 mm or less is formed between the disk body and the nitride layer
Data Source
AI summary
A method of manufacturing a brake disk made of gray cast iron is disclosed. The method includes casting a disk body using gray cast iron containing 3.1 wt % to 3.7 wt % of C; machining a surface of the cast disk body; nitriding the disk body by exposing the machined surface to a temperature in the range of 540° C. to 580° C. for 50 min to 70 min, and coating the nitrided disk body.