Roller Chain Wear Resistance via Dissimilar Nitrided Steel
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Roller chains experience excessive wear and reduced corrosion resistance due to insufficient lubrication, and existing nitriding methods fail to achieve optimal wear resistance when using identical materials for components in frictional engagement.
Innovation Solution
A roller chain design where components in frictional engagement, such as pins and bushings, utilize austenitic stainless steel with an S-phase nitrided at 400-500°C and stainless ferritic steel nitrided at 1000-1200°C, respectively, to enhance wear resistance while maintaining corrosion resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If gas nitriding, plasma nitriding or impulse-plasma nitriding is used to harden the surface of austenitic steel, then wear resistance is improved, but corrosion resistance is significantly reduced
Solution Approach 1:
The patent applies ion implantation at temperatures below 400°C instead of conventional nitriding at temperatures above 500°C. This parameter change in temperature prevents the formation of chromium nitride, thereby maintaining corrosion resistance while still achieving surface hardening and improved wear resistance through nitrogen incorporation into the austenitic steel lattice.
Solution Approach 2:
The patent replaces thermal nitriding processes (gas nitriding, plasma nitriding) with ion implantation. This substitution allows nitrogen to be introduced into the steel surface at lower temperatures through direct ion bombardment, avoiding the formation of brittle chromium nitride compounds that compromise corrosion resistance.
2Strength
If conventional nitriding is used to increase surface hardness, then wear resistance is improved, but the formation of chromium nitride reduces corrosion resistance
Solution Approach 1:
The patent changes the temperature parameter from conventional nitriding (above 500°C) to ion implantation (below 400°C). This temperature reduction prevents chromium nitride formation while still achieving the desired surface hardness and wear resistance through controlled nitrogen incorporation into the austenitic steel.
3Ease of manufacture
If identical materials are used for components in frictional engagement, then manufacturing simplicity is improved, but wear resistance is insufficient
Solution Approach 1:
The patent applies different nitriding treatments to different components based on their specific functional requirements. Pins receive ion implantation at one set of parameters while bushings receive ion implantation at different parameters, creating locally optimized surface properties that enhance wear resistance in frictional contacts while maintaining manufacturing simplicity.
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 material combination significantly improves wear resistance between components, outperforming identical material configurations, and supports a hard outer layer with adequate core strength.
Implementation Method 1
the diffusion of nitrogen into the austenitic steel is extremely slow at lower temperatures
Implementation Method 2
The S-phase of the austenitic steel, which is also called expanded austenite, represents a solid solution of nitrogen in the austenitic steel. The initial austenite lattice is expanded due to the incorporation of nitrogen.
Implementation Method 3
implantation of nitrogen, which can be carried out at temperatures below 400° C. and with an adequate speed, is an approach which is acceptable from an economic point of view
Implementation Method 4
A high resistance of the chain parts to corrosion is also desired. This is provided by austenitic steels which are alloyed with chromium.
Data Source
AI summary
A roller chain includes pins, bushings, rollers, inner plates and outer plates. Two bushings are connected to one another in each case by way of at least two inner plates to form a chain link. Two consecutive chain links are articulately connected to one another in each case by way of each bushing being seated on a pin projecting beyond both ends of the bushing. At least one combination, which consist of two mutually frictionally engaged components—the pin and bushing on the one hand, the bushing and roller on the other hand,—include one component consisting of austenitic stainless steel with an S-phase formed at least on the surface by way of nitriding at a temperature between about 400° C. and 500° C., and another component consisting of a stainless ferritic steel, which at least on the surface, is nitrided at a temperature between about 1000° C. and 1200° C.