Enhancement of Fatigue Life in St37 Steels by Carburizing Process

2021 ◽  
Vol 105 ◽  
pp. 59-67
Author(s):  
Jalal Joudaki ◽  
Mehdi Safari
Keyword(s):  
Fatigue Life ◽  
Fatigue Tests ◽  
Diffusivity Coefficient ◽  
Bending Fatigue ◽  
Steel Material ◽  
Wide Range ◽  
Different Temperatures ◽  
St37 Steel ◽  
Fatigue Life Test ◽  
Carburizing Process

Carburizing is a heat treatment process, which used widely for surface hardening. In this process, the parts are placed in a concentrated atmosphere of Carbon atoms. The carbon atoms diffuse in the samples from the surface. In the present article, the effects of carburizing temperature on fatigue life will be studied. The St37 steel material is selected for study due to its wide range of usage in industry and little attention on the carburizing of this material. The samples are prepared by implementing the carburizing process at different temperatures (300, 400, 500, and 600 °C). The holding time is 1 hour for all samples. The two-point bending fatigue tests had been carried out on constant loading stresses. The results of the fatigue life test show that the fatigue life enhances the carburizing process. The fatigue life improved from about 45000 cycles to about 65000 cycles (about 44% increase) by increasing the temperature from 300°C to 600°C. Holding at higher temperatures leads to an increase in fatigue life smoothly due to the increase in the diffusivity coefficient. Also, the fracture surface demonstrates that the crack initiation starts from outer surfaces very slowly and failure happens as a brittle fracture in the samples.

scholarly journals Effect of Elevated Temperature on Bending Fatigue Behavior for Neat and Reinforced Polyamide 6,6

2020 ◽  
Vol 23 (3) ◽  
pp. 232-237
Author(s):  
Orhan Sabah Abdullah ◽  
Shaker S. Hassan ◽  
Ahmed N. Al-khazraji
Keyword(s):  
Fatigue Life ◽  
Elevated Temperatures ◽  
Fiber Composite ◽  
Fatigue Behavior ◽  
Fatigue Tests ◽  
Bending Test ◽  
Test Machine ◽  
Carbon Fiber Composite ◽  
Bending Fatigue ◽  
Different Temperatures

Recently, considering polymer composite in manufacturing of mechanical parts can be caused a fatigue failure due to the very long time of exposure to cyclic loading and may at environmental temperatures higher than their glass transition temperature; therefore, in this paper, a comprehensive investigation for bending fatigue behavior at room and elevated temperatures equal to 60 °C, 70°C, and 80 °C will be done. Rotating bending test machine was manufactured for this purpose supplied with a connected furnace to perform fatigue tests at elevated temperatures. The obtained results appeared that the increase in applied stress and temperature caused a clear reduction in fatigue life; also the addition of carbon nanotubes enhanced the fatigue life at different temperatures by 183%, 205%, 218%, and 240%, respectively while the addition of short carbon fibers improved fatigue life by 324%, 351%, 387%, and 415%, respectively. As well as, Polyamide 6,6/carbon fiber composite appeared fatigue limit at temperatures equal to 20°C and 60°C and stresses approximately equal to 55 MPa and 38 MPa respectively.

Relationship Between Fatigue Life Distribution, Notch Configuration, and S-N Curve of a 2024-T4 Aluminum Alloy

1985 ◽  
Vol 107 (3) ◽  
pp. 214-220 ◽  
Author(s):  
T. Shimokawa ◽  
Y. Hamaguchi
Keyword(s):  
Aluminum Alloy ◽  
Fatigue Life ◽  
Stress Amplitude ◽  
Fatigue Tests ◽  
Test Results ◽  
Notched Specimens ◽  
Wide Range ◽  
Life Distributions ◽  
The Relationship ◽  
Test Stress

The objective of this study is to identify the most closely related variable to the distribution of fatigue life in unnotched and three kinds of notched 2024-T4 aluminum alloy specimens. Carefully designed fatigue tests under a constant temperature and humidity condition provided fatigue life distributions over a wide range of stress amplitude. This study used about 1000 specimens. On the basis of the test results, the dependence of the scatter in fatigue life on notch configuration, the period to crack initiation, the level of stress amplitude, the median fatigue life, and the slope of the median S-N curve is investigated, and the relationship between the distributional form of fatigue life and the shape of the median S-N curve is discussed. It is concluded that the slope and shape of the median S-N curve in the vicinity of the test stress level are closely related to the scatter and distributional form of fatigue life respectively. This is common to the unnotched and three kinds of notched specimens. A variability hypothesis to correlate the median S-N curve with fatigue life distributions is examined.

The Effect of Asphalt Binder Aging on Fatigue Performance of Evotherm WMA

2012 ◽  
Vol 535-537 ◽  
pp. 1686-1692
Author(s):  
Yong Chun Qin ◽  
Sui Yuan Wang ◽  
Wei Zeng ◽  
Xiao Pei Shi ◽  
Jian Xu ◽  
...  
Keyword(s):  
Fatigue Life ◽  
Asphalt Binder ◽  
Asphalt Mixture ◽  
Warm Mix Asphalt ◽  
Fatigue Tests ◽  
Fatigue Performance ◽  
Asphalt Binders ◽  
Different Temperatures ◽  
Binder Aging ◽  
Lower Production

One of the main benefits advertised with the use of warm mix asphalt (WMA) is the decreasing aging of the asphalt binder resulting from the lower production temperature compared to conventional hot mix asphalt (HMA). Some tests were performed to determine the asphalt binder aging properties from WMA and HMA. Asphalt binders were recovered by extraction and distillation from asphalt mixtures premixed at different temperatures (140°C, 160°C, 180°C for HMA, 100°C and 120°C for WMA) in the mixing plant. Penetration@25°C, softening point (R&B) and rotational Brookfield viscosity tests were carried out. Results show that the aging of asphalt binder increases as the mixing temperature is elevated, and remarkably accelerates at the temperatures higher than 150°C. Warm mix asphalt (for example, mixing temperature at 100°Cor 120°C) can greatly reduce the aging of asphalt. Aging of the asphalt binder is one of the factors that would affect the mixture’s fatigue life. Four-point beam fatigue test samples were mixed and compacted at 140°C for HMA and 120°C for WMA, and fatigue tests with a frequency of 10 Hz and three constant strain levels (150 micro-strain, 300 micro-strain, 450 micro-strain, respectively) were performed. Results show that WMA’s fatigue life was higher than the control HMA, which indicates that it may reduce aging of asphalt binder and improve fatigue performance of asphalt mixture at lower production temperatures.

Effect of Aggregate Gradation on Fatigue Life of Asphalt Concrete Mixes

1998 ◽  
Vol 1630 (1) ◽  
pp. 62-68 ◽  
Author(s):  
Jorge B. Sousa ◽  
Jorge C. Pais ◽  
Manuel Prates ◽  
Rui Barros ◽  
Pierre Langlois ◽  
...  
Keyword(s):  
Fatigue Life ◽  
Asphalt Concrete ◽  
Laboratory Tests ◽  
Fatigue Tests ◽  
Test Protocol ◽  
Predictive Equations ◽  
Aggregate Gradation ◽  
Bending Fatigue ◽  
Four Point Bending ◽  
Highway Research

Four-point bending fatigue tests following the Strategic Highway Research Program (SHRP) M009 test protocol were executed to investigate to what extent gradation has an effect on fatigue performance of asphalt aggregate mixes. Gradations and mixes were selected that would satisfy all volumetric Superpave designs passing below the restricted zone. Other mixes were prepared with gradations passing through and above the restricted zone. The measured fatigue lives of 130 actual laboratory tests were compared with predictions by the Shell, Asphalt Institute, and SHRP-A003A fatigue-predictive equations.

Effect of different temperatures on the fatigue behavior of interference fitted plates of Al-alloy 7075-T6

2017 ◽  
Vol 233 (7) ◽  
pp. 1324-1335
Author(s):  
H Taghizadeh ◽  
TN Chakherlou
Keyword(s):  
Finite Element ◽  
Fatigue Life ◽  
Thermal Cycle ◽  
Fatigue Behavior ◽  
Three Dimensional ◽  
Fatigue Tests ◽  
Al Alloy ◽  
Interference Fit ◽  
Short Period ◽  
Different Temperatures

The effect of short time exposure to thermal cycle on the fatigue life of interference fitted fastener holes was evaluated by experimental and numerical method in Al-alloy 7075-T6. When interference fitted holes are subjected to temperature, the pre-stresses produced by interference fit may be considerably redistributed. To investigate the pre-stresses redistribution and its effect on the fatigue life of interference fitted specimens, two different temperatures (i.e. 60 ℃ and 120 ℃), apart from room temperature, were selected. The fatigue tests were performed to obtain S–N curves. Tangential pre-stress distribution was analyzed by the finite element method. Three-dimensional stress distributions of interference fit process have been determined around the hole at three temperatures: 25 ℃, 60 ℃, and 120 ℃. The finite element analyses justify the experimentally observed fatigue test behavior. The results show that the short period thermal cycle could improve the fatigue life of the prepared samples.

Investigating Machining Impact on Fatigue Variance: A Machining Quality Perspective

2004 ◽  
Vol 127 (3) ◽  
pp. 492-502 ◽  
Author(s):  
Xiaoping Yang ◽  
C. Richard Liu
Keyword(s):  
Fatigue Life ◽  
Data Center ◽  
Room Temperature ◽  
Fatigue Tests ◽  
Machining Processes ◽  
Case Scenario ◽  
Bending Fatigue ◽  
Machining Quality ◽  
Four Point Bending ◽  
The Impact

Fatigue life of nominally identical structures under nominally identical loading conditions can scatter widely. This study has investigated the impact of machining processes on such scatters. After Ti 6Al-4V samples were surface ground and face turned, they were subject to constant amplitude four-point bending fatigue tests under room temperature. The best-case scenario of process capability ratios of fatigue for these samples were evaluated with assumed tolerances of fatigue life. Based on these ratios, the numbers of nonconforming parts were estimated. Under the machining conditions from the Machining Data Handbook (Machining Data Center, Cincinnati, 1980), up to 39% of samples due to one process are expected to be nonconforming, whereas only up to 0.6% of samples due to the other process are expected to be nonconforming. The ramifications in terms of cost for machining quality control due to the different capability ratios have been discussed. The current findings indicate an urgent need to further the study of this issue in a scientific manner.

Bending Fatigue Life Prediction of Fillet Rolled Crankshafts

2013 ◽  
Vol 275-277 ◽  
pp. 174-178 ◽  
Author(s):  
Ke Bao ◽  
Ri Dong Liao
Keyword(s):  
Fatigue Life ◽  
Life Prediction ◽  
Three Dimensional ◽  
Local Stress ◽  
Fatigue Tests ◽  
Fatigue Life Prediction ◽  
Stress Strain ◽  
Bending Fatigue ◽  
Bending Strain ◽  
Stress Computation

The influence of residual stesses must be considered in bending fatigue life prediction of fillet rolling crankshafts. In this paper, the stress/strain distributions near fillet during fatigue tests are calculated by finite element method. In residual stress computation, the three dimensional flexible contact model is adopted, and in bending strain computation, the static analysis are selected. Then, bending fatigue life prediction is performed by local stress-strain approach based on the residual stess and bending strain amplitude, and the results agree with the bending fatigue test.

Fatigue Life Prediction of CFRP Laminates under Variable Stress Amplitude and Frequency

2007 ◽  
Vol 334-335 ◽  
pp. 445-448 ◽  
Author(s):  
Masayuki Nakada ◽  
Junji Noda ◽  
Yasushi Miyano
Keyword(s):  
Fatigue Life ◽  
Cyclic Loading ◽  
Life Prediction ◽  
Statistical Approach ◽  
Stress Amplitude ◽  
Fatigue Tests ◽  
Fatigue Life Prediction ◽  
Bending Fatigue ◽  
Cfrp Laminates ◽  
Three Point Bending

This paper is concerned with the fatigue life prediction of CFRP laminates under variable cyclic loading using the linear cumulative damage (LCD) rule with statistical approach. Three-point bending fatigue tests for plain-woven CFRP laminates were carried out undervarious cyclic loading with constant and variable stress amplitude and frequency. As results, the applicability of LCD rule to the flexural fatigue life was confirmed for this CFRP laminates.

Safety Assessment of Steels and Welds Under Cyclic and Monotonic Loadings at Low Temperatures

1984 ◽  
Vol 106 (4) ◽  
pp. 473-479
Author(s):  
N. Urabe ◽  
A. Yoshitake ◽  
H. Kagawa
Keyword(s):  
Fracture Toughness ◽  
Fatigue Life ◽  
Brittle Fracture ◽  
Low Temperatures ◽  
Safety Assessment ◽  
Loading Rate ◽  
Fracture Initiation ◽  
Fatigue Tests ◽  
Loading Rates ◽  
Wide Range

In order to investigate the mechanisms and the factors to govern the brittle fracture initiation during the fatigue crack propagation at low temperatures, fracture toughness tests under wide range of loading rates, fatigue tests at low temperatures and fracture toughness tests after having been given pre-loading were performed on steels and weld junctions. The fatigue fracture toughness Kfc was estimated as equivalent as the fracture toughness Kc under the monotonic tensile loading if they were compared at the same loading rate, since the residual stress due to the cyclic loading was less effective on the brittle fracture initiation. The calculated fatigue life based on Paris’s formula taken into consideration of the crack closure phenomena showed a good one-by-one agreement with the observed fatigue life up to the brittle fracture initiation. Therefore, a design curve was preliminarily drawn to determine the fatigue life at low temperatures.

Rotating-Beam Reversed-Bending Fatigue Curves

2004 ◽  
pp. 253-291
Keyword(s):  
Fatigue Tests ◽  
Rotating Beam ◽  
Aluminum Casting ◽  
Data Set ◽  
Bending Fatigue ◽  
Casting Alloys ◽  
Wide Range

Abstract This data set contains the results of rotating-beam reversed-bending fatigue tests for a wide range of aluminum casting alloys. These fatigue curves are the results of tests on individual lots of material considered representative of the respective alloys and tempers.

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