Carburized Steel Gear Microstructure Control
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Solution Overview
Problem
Conventional steel technologies for carburized gears fail to stabilize thermal strain during heat treatment, leading to uneven gear tooth dimensions and increased vibrations, which affect the quiet operation of machinery.
Innovation Solution
The development of steel with specific chemical compositions and controlled manufacturing processes, including precise control of casting and cooling rates, to achieve uniform ferrite and bainite structures in gear teeth, thereby stabilizing thermal strain.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional steel technologies are used for carburized gears, then manufacturing processes can be completed, but thermal strain on gear teeth becomes unstable leading to dimensional inaccuracy
Solution Approach 1:
The patent applies parameter changes by precisely controlling chemical composition parameters (C: 0.15-0.25%, Si: 0.30-0.70%, Mn: 0.20-0.60%, Cr: 1.00-2.00%, Mo: 0.10-0.50%) and processing parameters (casting temperature, cooling rate, heating rate) to stabilize thermal strain and achieve uniform microstructure, thereby improving dimensional accuracy of gear teeth
Solution Approach 2:
The patent creates a composite microstructure consisting of ferrite and bainite phases through controlled composition and heat treatment, where the specific combination of alloying elements promotes a dual-phase structure that reduces thermal strain variation and improves dimensional stability during carburizing hardening
2Ease of operation
If thermal strain is not stabilized, then manufacturing can proceed, but symmetrical shape is lost and vibrations increase during operation
Solution Approach 1:
By controlling chemical composition parameters and thermal processing parameters, the patent achieves uniform microstructure that maintains symmetrical gear tooth shapes, preventing vibrations and ensuring quiet operation during use
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 effectively stabilizes thermal strain on gear teeth, ensuring dimensional accuracy and reducing vibrations, thus enhancing the quiet operation of machinery.
Implementation Method 1
gears for use in automobiles, construction machinery, industrial machinery, and the like are generally used after receiving carburizing hardening after machining
Implementation Method 2
carburizing hardening after machining
Implementation Method 3
The dimensional accuracy of gear teeth is attributable to deformation associated with heat treatment during carburizing hardening (hereinafter referred to as thermal strain)
Data Source
Figure 1
AI summary
Steel according to one embodiment of the present invention has predetermined chemical components, wherein in a region where a distance r from the center of a cross-section perpendicular to the length direction satisfies 0.7R ≤ r ≤ 0.9R, structures include ferrite and bainite, the average fraction of the ferrite is in the range of 40 to 70% in terms of area ratio, the total average fraction of the structures other than the ferrite and the bainite is 0% or more and 3% or less on average, and the balance includes bainite; and the standard deviation of a ferrite fraction in the region is 4% or less.