Sub-surface fatigue strength of a steel

Wear ◽  
1969 ◽  
Vol 14 (4) ◽  
pp. 306
Keyword(s):  
Fatigue Strength ◽  
Surface Fatigue

Fatigue Failure and Strength Evaluation of Traction Drive Rollers

2000 ◽  
Author(s):  
Masana Kato ◽  
Gang Deng ◽  
Masashi Yamanaka ◽  
Ryoji Yamamoto ◽  
Noboru Ono ◽  
...  
Keyword(s):  
Fatigue Life ◽  
Fatigue Strength ◽  
Crack Growth ◽  
Surface Crack ◽  
Traction Force ◽  
Fatigue Tests ◽  
Slip Ratio ◽  
Traction Drive ◽  
Surface Fatigue ◽  
Surface Crack Growth

Abstract The surface fatigue failures of the traction drive rollers are different to that of gears and bearings because of the high traction force, skew and small slip ratio. In this research, fatigue tests of traction rollers were performed in different slip ratios and skew angles. The effects of running conditions on the fatigue lives of traction drive rollers are clarified and explained based on the surface crack growth and wear situations. Although a higher slip ratio will make a lower fatigue life, the fatigue strength will increase inversley under the skew conditions, because of the differences in mechanical and tribological condition for surface crack growth and the severe surface wear, which diminishes the surface crack length. For evaluation of the effects of such as slip ratio and skew on the fatigue strength of traction rollers, a new method is put forward in which the relationship between the surface temperature index and fatigue life is used instead of S-N curve.

scholarly journals Effect of Carburizing and Nitriding on Fatigue Properties of 18Cr2Ni4WA Steel in Very High Cycle Fatigue Regime

2021 ◽  
Vol 45 (3) ◽  
pp. 207-215
Author(s):  
Zhenduo Sun ◽  
Dongbo Hou ◽  
Wei Li
Keyword(s):  
Fatigue Life ◽  
Fatigue Strength ◽  
High Cycle Fatigue ◽  
Fatigue Properties ◽  
Cycle Fatigue ◽  
Internal Defect ◽  
Surface Fatigue ◽  
Very High Cycle Fatigue ◽  
The Relationship ◽  
Very High

The work aims to study the influence of carburizing and nitriding on fatigue properties of 18Cr2Ni4WA high strength steel in very high cycle fatigue regime. Very high cycle fatigue tests were carried out on 18Cr2Ni4WA Steel after carburizing and nitriding respectively. The micro morphology of fatigue fracture was observed by scanning electron microscope, the failure mode and failure mechanism were discussed. The relationship between fatigue life and defect size, FGA size, fish eye size of fracture was analyzed. The characteristic size of defects is evaluated by Gumbel, Weibull and GEV distribution functions, and a modified Akiniwa fatigue life prediction model considering the relationship between FGA size and inclusion size was established. The results showed that, nitriding and carburizing treatment improve the surface fatigue limit of the steel. The fatigue life decreases with the increase of internal defect size and FGA size. After carburizing and nitriding treatment, the internal fatigue strength of the specimen decreases slightly. When the failure probability is 99%, the internal defect sizes of nitrided specimens calculated by Weibull, Gumbel and GEV distributions are 141.5 μm, 148.4 μm and 211.7 μm respectively. The calculated internal defect sizes of carburized specimens are 47 μm, 67.8 μm and 40 μm respectively. Compared with the experimental data, the fatigue strength predicted by GEV is the most appropriate. carburizing and nitriding treatment can improve the surface fatigue strength of 18Cr2Ni4WA steel, but slightly reduce the internal fatigue strength. The prediction result of the new model is conservative when the failure probability is 99%, which is suitable for engineering application.

Tooth Surface Fatigue Strength of Normalized Steel Conical Involute Gears

2000 ◽  
Author(s):  
Tatsuya Ohmachi ◽  
Koji Iizuka ◽  
Hidenori Komatsubara ◽  
Ken-ichi Mitome
Keyword(s):  
Fatigue Strength ◽  
Contact Stress ◽  
Testing Machine ◽  
Hertzian Contact ◽  
Tooth Surface ◽  
Paper Test ◽  
Surface Fatigue ◽  
Involute Gears ◽  
Conical Gears ◽  
Hertzian Contact Stress

Abstract The tooth surface fatigue strength of the conical involute gear is evaluated in this paper. Test gears are straight intersecting-axis conical gears. The material of the test gear is normalized steel. The power circulating testing machine is used in this experiment. The circulating torque is kept constant and the number of times of contact is 107. The tooth surface life is evaluated by the pitting area rate. The critical value of the circulating torque is found between 147 N·m and 157 N·m. For critical torque, the pitting area rate does not progress over 4%. The Hertzian contact stress of the test gear is calculated at the circulating torque. The contact stress should be evaluated in consideration of the wearing effects.

Surface Fatigue Strength of Carburized Gear Material for Long Fatigue Lives Based on Reliability Evaluation

2000 ◽  
Author(s):  
L. H. Hsu ◽  
H. Y. Cheng ◽  
K. C. Hsu
Keyword(s):  
Fatigue Strength ◽  
Fatigue Test ◽  
Gear Tooth ◽  
Likelihood Method ◽  
Test Model ◽  
Surface Fatigue ◽  
Surface Durability ◽  
Specific Material ◽  
Carburized Gear ◽  
Different Levels

Abstract The study used a fatigue test model to investigate the surface fatigue strength of a specific carburized gear material, i.e. AISI 4118. A set of test specimens is designated to simulate the mechanics of gear tooth meshing. A friction, wear, and tribological tester is used to conduct the surface contact stress generated between the test specimens. The surface fatigue lives of the test specimens under different levels of contact stresses have been detected. Based on the maximum likelihood method proposed by Ling and Pan, the R-S-N curves of the surface durability of the specific material have been established using the experimental data of the fatigue test. Especially the fatigue strength for long fatigue lives at required reliability can be estimated.

Sub-Surface Fatigue Strength of a Steel

1969 ◽  
Vol 11 (4) ◽  
pp. 432-443 ◽  
Author(s):  
P. F. Bray
Keyword(s):  
Fatigue Strength ◽  
Residual Stresses ◽  
Fatigue Limit ◽  
Fatigue Tests ◽  
Bending Fatigue ◽  
Surface Fatigue ◽  
Test Pieces ◽  
Surface Failure ◽  
Rotating Bending Fatigue ◽  
Rotating Bending

Rotating bending fatigue tests on En 40B steel gave a fatigue limit for surface failure of 30·5 tonf/in2. With nitrided test-pieces sub-surface failures were produced and, with no allowance being made for residual stresses, a fatigue limit of 34·5 tonf/in2 was obtained for sub-surface failure. In the absence of residual stresses this fatigue limit would probably have been higher.

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