Influence of the Nitrided Layer Structure on the Micro-Pitting and Wear Behavior of Slow-Running Nitrided External Gears
Abstract
:1. Introduction
2. Materials and Methods
2.1. Material and Heat Treatment
2.2. Test Gears
2.3. Gear Testing
2.4. Determination of the Wear Behavior
- : Minimum lubricant film thickness in C
- : Radius of relative curvature in C
- : Pressure-viscosity coefficient
- : Relative modulus of elasticity
- : Dynamic viscosity at bulk temperature
- : Kinematic viscosity
- : Working pressure angle
- : Applied torque
- : Base diameter
- : Gear face width
- : Linear wear coefficient
- : Mass loss
- : Gear face width
- : Normal module
- : Number of teeth
- : Density
- : Applied load cycles
- : Linear wear coefficient, revaluated regarding the test conditions acc. to Plewe
- : Mass loss
- : Gear face width
- : Normal module
- : Number of teeth
- : Density
- : Applied load cycles
- : Nominal contact stress referring to the test conditions acc. to Plewe
- : Nominal contact stress referring to the carried out tests
- : Radius of relative curvature referring to the test conditions acc. to Plewe
- : Radius of relative curvature referring to the carried out tests
- : Wear-effective specific sliding referring to the test conditions acc. to Plewe
- : Wear-effective specific sliding referring to the carried out tests
3. Results
3.1. Results of the Nitriding Treatments
3.2. Results within the Load Stage Tests
3.3. Results from the Speed Stage Test
4. Discussion
4.1. Micro-Pitting Behavior
4.2. Wear Behavior
4.3. Model of the Damage Mechanism and Damage Development
5. Conclusions
- The compound layer is decisive for the tribological behavior of nitrided gears.
- No micro-pitting could be observed as long as the porous zone was present.
- The wear behavior was not influenced by compound layer or porous zone thickness.
- Compound layers with either 100% γ’-nitride or with a high percentage of ε-nitride (>50%) showed an increased wear resistance, while only low contents of ε-nitride have a negative effect on the wear behavior.
Author Contributions
Funding
Data Availability Statement
Conflicts of Interest
References
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Source | C | Si | Mn | P | S | Cr | Mo | V |
---|---|---|---|---|---|---|---|---|
ISO 683-5 | 0.27–0.34 | max. 0.40 | 0.40–0.70 | max. 0.025 | max. 0.035 | 2.30–2.70 | 0.15–0.25 | 0.10–0.20 |
OES | 0.31 | 0.24 | 0.67 | 0.010 | 0.014 | 2.48 | 0.22 | 0.16 |
Parameter | Unit | Type C (External Gears) | ||
---|---|---|---|---|
Pinion | Wheel | |||
Normal module | mm | 4.5 | ||
Number of teeth | - | 16 | 24 | |
Face width | mm | 14.0 | ||
Normal pressure angle | ° | 20.0 | ||
Working pressure angle | ° | 22.44 | ||
Helix angle | ° | 0 | ||
Transverse contact ratio | - | 1.436 | ||
Addendum modification coefficient | - | 0.1817 | 0.1715 | |
Reference diameter | mm | 72.0 | 108.0 | |
Tip circle diameter | mm | 82.5 | 118.4 | |
Center distance | mm | 91.5 |
Variant | Core Hardness | Core Strength * | Phases in the Compound Layer | |||
---|---|---|---|---|---|---|
in mm | in µm | in µm | in HV10 | in N/mm2 | ||
R (reference) 510 °C 30 h | 0.38 | 11.4 | 3.7 | 276 | 861 | 56% ε-nitride 35% γ’-nitride 9% cementite |
VS1 520 °C 42 h = 1 | 0.43 | 4.1 | 0.5 | 326 | 1020 | 100% γ’-nitride |
VS2 520 °C 42 h = 3 | 0.53 | 12.6 | 4.5 | 327 | 1020 | 15% ε-nitride 85% γ’-nitride |
NC 550 °C 21 h = 1 = 0.1 | 0.43 | 17.6 | 4.3 | 321 | 1003 | 47% ε-nitride 53% γ’-nitride |
Variant | Location | Hardness | Standard Deviation |
---|---|---|---|
HV | |||
R (reference) 510 °C 30 h | Compact compound layer | 1049 | 53.4 |
VS1 520 °C 42 h = 1 | Compact compound layer | 1094 | 90.4 |
VS2 520 °C 42 h = 3 | Compact compound layer | 1158 | 79.8 |
NC 550 °C 21 h = 1 = 0.1 | Compact compound layer | 1032 | 24.7 |
Porous zone | 914 | 39.3 |
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Hoja, S.; Geitner, M.; Zornek, B.; Hoffmann, F.; Tobie, T.; Stahl, K.; Fechte-Heinen, R. Influence of the Nitrided Layer Structure on the Micro-Pitting and Wear Behavior of Slow-Running Nitrided External Gears. Lubricants 2022, 10, 88. https://doi.org/10.3390/lubricants10050088
Hoja S, Geitner M, Zornek B, Hoffmann F, Tobie T, Stahl K, Fechte-Heinen R. Influence of the Nitrided Layer Structure on the Micro-Pitting and Wear Behavior of Slow-Running Nitrided External Gears. Lubricants. 2022; 10(5):88. https://doi.org/10.3390/lubricants10050088
Chicago/Turabian StyleHoja, Stefanie, Michael Geitner, Bernd Zornek, Franz Hoffmann, Thomas Tobie, Karsten Stahl, and Rainer Fechte-Heinen. 2022. "Influence of the Nitrided Layer Structure on the Micro-Pitting and Wear Behavior of Slow-Running Nitrided External Gears" Lubricants 10, no. 5: 88. https://doi.org/10.3390/lubricants10050088