Martensitic Rolling Bearing Structure Against White Structure Spalling
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Solution Overview
Problem
Existing technologies fail to sufficiently suppress the occurrence of white structure spalling in rolling bearings, which is caused by hydrogen-induced changes in the metallographic structure, leading to reduced bearing life.
Innovation Solution
A rolling bearing structure is designed with a specific range of solid solution carbon content in the martensitic structure (0.35 to 0.65 mass %) and a limited volume ratio of spheroidized carbides (4.5% or less with a diameter of 200 nm or more) to inhibit white structure spalling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a large amount of Cr is added to suppress white structure spalling, then the resistance to white structure spalling is improved, but the steel material becomes brittle and quenching temperature increases reducing productivity
Solution Approach 1:
The invention changes the chemical composition parameters by limiting Cr to 2.00 mass% or less while optimizing other alloying elements (C: 0.95-1.30 mass%, Si: 0.15-0.60 mass%, Mn: 0.50-1.50 mass%, Mo: 0.10-0.50 mass%) to achieve both white structure spalling resistance and maintained productivity through balanced alloy design
Solution Approach 2:
The invention creates a composite alloy system combining multiple elements (C, Si, Mn, Cr, Mo) in specific proportions that work synergistically to provide white structure spalling resistance without the brittleness and productivity issues caused by excessive Cr alone
2Reliability
If alloying elements are adjusted to suppress white structure spalling, then the resistance to white structure spalling is improved, but the material cost increases significantly
Solution Approach 1:
The invention optimizes the concentration parameters of alloying elements to achieve cost-effective composition: limiting expensive elements like Cr (≤2.00 mass%) while maintaining protective effects through optimized levels of C (0.95-1.30 mass%), Si (0.15-0.60 mass%), Mn (0.50-1.50 mass%), and Mo (0.10-0.50 mass%)
Solution Approach 2:
The invention replaces expensive Cr-heavy compositions with a more balanced, cost-effective alloy formulation that achieves similar or better white structure spalling resistance through synergistic combination of multiple moderate-level alloying elements rather than relying on large amounts of expensive Cr
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 proposed structure effectively suppresses white structure spalling, enhancing the rolling contact fatigue life of the bearing.
Implementation Method 1
the decomposition of the lubricating oil generates hydrogen, and the generated hydrogen enters steel and causes a change in the metallographic structure in some cases. When the change in the metallographic structure occurs, fatigue cracks are generated from the interface between the structure changed portion and a normal portion
Data Source
AI summary
A rolling bearing contains a structure having a solid solution carbon amount in a martensitic structure after heat treatment of 0.35 mass % or more and 0.65 mass % or less and a volume ratio of spheroidized carbides having a diameter of 200 nm or more of 4.5% or less.