Rolling Bearing Steel Composition for High-Temperature Durability
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Solution Overview
Problem
Rolling members used in high-temperature environments or water-infiltrated environments face issues such as reduced lifespan due to alloying elements affecting workability and manufacturing costs, along with problems like hydrogen embrittlement and surface damage from inadequate lubrication and rust.
Innovation Solution
A rolling member composed of steel with specific carbon, silicon, manganese, nickel, chromium, molybdenum, and vanadium content, with a hardened surface layer and controlled carbide distribution to enhance hardness and resistance, while minimizing alloying elements to maintain workability and reduce manufacturing costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If alloying elements are added to steel to improve hardness and wear resistance, then the rolling member's durability is improved, but the workability and manufacturing cost deteriorate
Solution Approach 1:
The patent applies parameter changes by precisely controlling the content ranges of multiple alloying elements (C: 0.3-0.4%, Si: 0.3-0.7%, Mn: 0.3-0.8%, Ni: 0.5-1.2%, Cr: 1.6-2.5%, Mo: 0.1-0.7%, V: 0.2-0.4%) to achieve the optimal balance between durability and workability. This quantitative parameter optimization allows the steel to form a hardened layer with appropriate hardness while maintaining manufacturability
Solution Approach 2:
The patent creates a composite structure with a hardened layer formed on the surface of the rolling member through controlled alloying. The hardened layer contains precipitated carbides and has different properties from the base steel, creating a composite material system that provides both surface durability and core toughness
2Reliability
If alloying elements are added to steel to improve hardness and wear resistance, then the rolling member's abrasion resistance is improved, but the manufacturing cost increases
Solution Approach 1:
The patent optimizes manufacturing cost by precisely controlling alloying element parameters within specific ranges. The controlled composition enables the formation of a hardened layer with appropriate carbide precipitation that provides abrasion resistance while avoiding excessive alloying that would increase material costs
Solution Approach 2:
The patent applies local quality by creating a hardened layer with specific properties on the surface of the rolling member, while the base steel maintains different properties. The hardened layer contains precipitated carbides and has higher hardness, providing localized abrasion resistance exactly where needed on the rolling surface
3Temperature
If the rolling member is designed for high-temperature environments, then the temperature resistance is improved, but dimensional stability deteriorates due to creep and secular dimensional change
Solution Approach 1:
The patent addresses dimensional stability at high temperatures by controlling alloying element parameters, particularly Cr (1.6-2.5%), Mo (0.1-0.7%), and V (0.2-0.4%), which form stable carbides and strengthen the steel matrix. This parameter optimization prevents excessive creep and secular dimensional change while maintaining high-temperature strength
4Adaptability or versatility
If the rolling member is used in water-infiltrated environments, then the application range is expanded, but hydrogen embrittlement and flaking occur due to hydrogen infiltration
Solution Approach 1:
The patent reduces susceptibility to hydrogen embrittlement by controlling the silicon content (0.3-0.7%) and the balance of alloying elements. The optimized composition minimizes hydrogen trapping sites while maintaining the hardened layer structure, allowing the rolling member to withstand water-infiltrated environments without premature flaking
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 solution provides a rolling member with extended lifespan in high-temperature and water-infiltrated environments, improved resistance to hydrogen embrittlement, and enhanced abrasion resistance, while maintaining workability and controlling manufacturing costs.
Implementation Method 1
a hardened layer having a larger carbon content than an inner portion is formed on a region including a surface
Implementation Method 2
a hardened layer having a larger carbon content than an inner portion is formed on a region including a surface
Implementation Method 3
the maximum grain size of carbides on the surface layer portion is not more than 10 μm, and an area ratio of the carbides on the surface layer portion is not less than 7% and not more than 25%
Data Source
AI summary
The invention provides a deep groove ball bearing which exhibits a long life even in a high-temperature environment or an environment involving the penetration of water in spite of its low alloying element content. The outer race, inner race and ball constituting the bearing are made of a steel which contains 0.3 to 0.4% of carbon, 0.3 to 0.7% of silicon, 0.3 to 0.8% of manganese, 0.5 to 1.2% of nickel, 1.6 to 2.5% of chromium, 0.1 to 0.7% of molybdenum and 0.2 to 0.4 of vanadium with the balance consisting of iron and impurities and in a total content of silicon and manganese of 1.0% or below, a total content of nickel and chromium of 2.3% or above and a total content of chromium, molybdenum and vanadium of 3.0% or below. Surface hardened layers are formed in the outer race, inner race and ball respectively and the surface hardened layers exhibit hardness of 725 to 800 HV, while the maximum particle size of carbides dispersed in the surface hardened layers is 10 μm or below and the area ratio thereof is 7 to 25%. Further, the inner parts exhibit hardness of 450 to 650 HV.