Effect of Weld Toe Burr Grinding on Fatigue Strength of Transverse Welded Specimens Made From DH36 Steel

2009 ◽  
Author(s):  
Helena Polezhayeva ◽  
Joong-Kyoo Kang ◽  
Joo-Ho Heo ◽  
Kwang-Seok Kim
Keyword(s):  
Fatigue Life ◽  
Fatigue Strength ◽  
High Cycle Fatigue ◽  
Welded Joint ◽  
Cycle Fatigue ◽  
Constant Amplitude ◽  
Joint Project ◽  
Improvement Factor ◽  
Weld Toe ◽  
Marine Engineering

The effect of weld toe grinding on fatigue life of welded joint has been studied by a number of investigators who have established that improvement factor on fatigue life is greater for higher tensile steels as compared with mild steels [1]. To establish the effect of weld toe grinding on the fatigue strength of joints made from DH36 steel, transverse welded specimens were tested under constant amplitude loading. This work was carried out by DAEWOO Shipbuilding and Marine Engineering Co. within Lloyds Register/DSME Joint Project. It was shown that the improvement factor on fatigue strength due to weld toe burr grinding for DH36 steel is above 1.5 for high cycle fatigue range.

The Effects of Specimen Size on the Very High Cycle Fatigue Properties of FV520B-I

2015 ◽  
Author(s):  
Ming Zhang ◽  
Weiqiang Wang ◽  
Aiju Li
Keyword(s):  
Fatigue Life ◽  
Fatigue Strength ◽  
High Cycle Fatigue ◽  
Specimen Size ◽  
Fatigue Properties ◽  
Test Results ◽  
Cycle Fatigue ◽  
Very High Cycle Fatigue ◽  
Heat Effects ◽  
Very High

The authors researched the effects of specimen size on the very high cycle fatigue properties of FV520B-I through ultrasonic fatigue testing. The test results showed that the very high cycle fatigue mechanism was not changed and the fatigue properties declined as the specimen size increased. The S-N curve moved downward and the fatigue life decreased under the same stress level maybe due to the heat effects of large specimens in tests. The fatigue strength and the fatigue life were predicted by relevant models. The prediction of fatigue strength was close to test result, and the prediction of fatigue life was less effective compared with the previous prediction of small size specimen test results.

High-Cycle Fatigue Life of AZ31 and AZ61 Magnesium Alloys

2013 ◽  
Vol 211 ◽  
pp. 83-88
Author(s):  
Marek Cieśla
Keyword(s):  
Fatigue Life ◽  
Fatigue Strength ◽  
Magnesium Alloys ◽  
High Cycle Fatigue ◽  
Fatigue Tests ◽  
Test Material ◽  
Cycle Fatigue ◽  
Structural Components ◽  
Asymmetry Coefficient ◽  
Fatigue Fractography

Usefulness of the magnesium alloys for construction of structural components is determined, apart from their low density, by a number of favourable mechanical properties and in the case of their use for components of transport means additionally by good fatigue strength. In this study, 12 mm diameter extruded rods of AZ31 and AZ61 magnesium alloys were used as test material. After extrusion the rods were annealed at a temperature of 400°C, with a 60 min soaking period and subsequent cooling in air. Cylindrical specimens with a diameter of d0 = 8 mm were made for the fatigue test under high-cycle rotary bending conditions with the cycle asymmetry coefficient R = -1. The tests were carried out for a limited fatigue strength range. Examination of microstructure of tested alloys and fatigue fractography were also performed. During the high-cycle fatigue tests it was found that the AZ61 alloy has a longer fatigue life. Based on the obtained results, fatigue life characteristics of the tested materials were drawn up.

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.

Fatigue Performance of Low Rigidity Titanium Alloy for Biomedical Applications

2004 ◽  
Vol 449-452 ◽  
pp. 1265-1268
Author(s):  
Toshikazu Akahori ◽  
Mitsuo Niinomi ◽  
Hisao Fukui ◽  
Akihiro Suzuki
Keyword(s):  
Fatigue Life ◽  
Fatigue Strength ◽  
Fatigue Limit ◽  
High Cycle Fatigue ◽  
Low Cycle Fatigue ◽  
Tangential Force ◽  
Solution Treatment ◽  
Beta Phase ◽  
Fretting Fatigue ◽  
Cycle Fatigue

Microstructures of Ti-29Nb-13Ta-4.6Zr (TNTZ) aged at temperatures between 573 and 723 K after solution treatment at 1063 K have super fine omega phase, or􀀂 both super fine alpha and omega phases, respectively in beta phase with an average grain diameter of 20 µm. Plain fatigue strength of TNTZ aged after solution treatment is much greater than that of as-solutionized TNTZ in both low cycle fatigue and high cycle fatigue life regions. This is due to the improvement of the balance of strength and ductility by the precipitation of alpha phase. Fretting fatigue strength of TNTZ conducted with various heat treatments decreases dramatically as compared with their plain fatigue strength in both low cycle fatigue and high cycle fatigue life regions. In this case, the decreasing ratio of fretting fatigue life increases with increasing the small crack propagation area where both the tangential force and frictional force at the contact plane of pad exist. In fretting fatigue in air, the ratio of fretting damage (Pf/Ff), where Pf and Ff stand for plain fatigue limit and fretting fatigue limit, respectively, increases with increasing elastic modulus. In fretting fatigue in Ringer’s solution, the passive film on specimen surface is broken by fretting action in TNTZ, which have excellent corrosion resistance, and, as a result, corrosion pits that lead to decreasing fretting fatigue strength especially in high cycle fatigue life region, are formed on its surface.

An energetic method to evaluate the macro and micro high-cycle fatigue behavior of the aluminum alloy

2017 ◽  
Vol 232 (8) ◽  
pp. 1456-1469 ◽  
Author(s):  
Junling Fan ◽  
Xinglin Guo ◽  
Yanguang Zhao
Keyword(s):  
Aluminum Alloy ◽  
Fatigue Life ◽  
Fatigue Strength ◽  
Energy Dissipation ◽  
High Cycle Fatigue ◽  
Fatigue Behavior ◽  
Cycle Fatigue ◽  
Thermal Signal ◽  
Dissipation Mechanism ◽  
Good Agreement

An energetic method is proposed to rapidly evaluate the macro- and microfatigue behavior of aluminum alloy in high-cycle fatigue. The theoretical correlation between the thermal signal and the energy dissipation during the fatigue process is established for the irreversible dissipation mechanism description. The energetic method is applied to predict the fatigue strength and the entire fatigue life of the aluminum alloy. Moreover, the energy dissipation is properly used to evaluate the microplastic behavior at the grain scale, which is responsible for the progressive movements of the internal microstructures. Experiments were carried out to validate the current energetic method, and good agreement was obtained between the predicted results and the traditional results. Thus, the current energetic method is confirmed to be promising for the macro and micro high-cycle fatigue behavior assessment.

High cycle fatigue behavior of Al1070 alloy severely deformed by equal channel angular pressing process

2016 ◽  
Vol 232 (6) ◽  
pp. 514-519 ◽  
Author(s):  
Mohammad Bagher Limooei ◽  
Morteza Zandrahimi ◽  
Ramin Ebrahimi
Keyword(s):  
Fatigue Life ◽  
Fatigue Strength ◽  
Equal Channel Angular Pressing ◽  
High Cycle Fatigue ◽  
Fatigue Behavior ◽  
Pure Aluminum ◽  
Fatigue Properties ◽  
Cycle Fatigue ◽  
Angular Pressing ◽  
Pressing Process

In the present work, equal channel angular pressing of commercial pure aluminum 1070 was performed up to 4 passes using route Bc. For equal channel angular pressing operation, a suitable die set was designed and manufactured. X-ray diffraction analysis was used to determine the microstructure of the equal channel angular pressing-ed material. The fracture surface morphology and microstructure after fatigue were investigated by scanning electron microscopy. Mechanical properties of the equal channel angular pressing-ed material were evaluated by hardness and tension tests. Also, cyclic deformation behavior of severe plastic deformation Al1070 has been studied and results show a significant variation in hardness, ultimate strength and fatigue properties in high cycle fatigue life. Coefficient of fatigue strength σ′f and Bridgman correction factor have been obtained by S-N curve and tension test specimens, respectively, and compared before and after equal channel angular pressing process. Also an useful relation has been derived between fatigue life ( Nf) and stress amplitude ( σa) in high cycle fatigue region. Results indicated that there was not clear relation between fatigue strength coefficient and true corrected fracture stress in this case.

scholarly journals The Effect of Baking Heat Treatment on the Fatigue Strength and Life of Shot Peened 4340M Landing Gear Steel

Materials ◽  
2020 ◽  
Vol 13 (24) ◽  
pp. 5711
Author(s):  
Seok-Hwan Ahn ◽  
Jongman Heo ◽  
Jungsik Kim ◽  
Hyeongseob Hwang ◽  
In-Sik Cho
Keyword(s):  
Heat Treatment ◽  
Fatigue Life ◽  
Fatigue Strength ◽  
Fatigue Limit ◽  
Shot Peening ◽  
High Cycle Fatigue ◽  
Landing Gear ◽  
Cycle Fatigue ◽  
Heat Treated ◽  
Ultrasonic Fatigue

In this study, the effect of baking heat treatment on fatigue strength and fatigue life was evaluated by performing baking heat treatment after shot peening treatment on 4340M steel for landing gear. An ultrasonic fatigue test was performed to obtain the S–N curve, and the fatigue strength and fatigue life were compared. The micro hardness of shot peening showed a maximum at a hardened depth of about 50 μm and was almost uniform when it arrived at the hardened depth of about 400 μm. The overall average tensile strength after the baking heat treatment was lowered by about 80–111 MPa, but the yield strength was improved by about 206–262 MPa. The five cases of specimens showed similar fatigue strength and fatigue life in high cycle fatigue (HCF) regime. However, the fatigue limit of the baking heat treated specimens showed an increasing tendency rather than that of shot peening specimens when the fatigue life was extended to the very high cycle fatigue (VHCF) regime. The effect of baking heat treatment was identified from improved fatigue limit when baking heat was used to treat the specimen treated by shot peening containing inclusions. The optimum temperature range for the better baking heat treatment effect could be constrained not to exceed maximum 246 °C.

Specimen Size Effect on Fatigue Properties of Surface-Micromachined Al-3%Ti Thin Films

2007 ◽  
Author(s):  
Jun-Hyub Park ◽  
Man Sik Myung ◽  
Yun-Jae Kim
Keyword(s):  
Thin Film ◽  
Fatigue Life ◽  
Fatigue Strength ◽  
Evaluation Method ◽  
High Cycle Fatigue ◽  
Test Procedure ◽  
Fatigue Tests ◽  
Test Method ◽  
Fatigue Properties ◽  
Cycle Fatigue

This paper presents high cycle fatigue properties of an Al-3%Ti thin film, used in a RF (radio-frequency) MEMS switch for a mobile phone and also describes new test method for obtaining static and dynamic characteristics of thin film and reliability evaluation method on MEMS device with thin film developed by authors. Durability should be ensured for such devices under cycling load. Therefore, with the proposed specimen and test procedure, tensile and fatigue tests were performed to obtain mechanical and fatigue properties. The specimen was made with dimensions of 1000μm long, 1.0μm thickness, and 3 kinds of width, 50, 100 and 150μm. High cycle fatigue tests for each width were also performed, from which the fatigue strength coefficient and the fatigue strength exponent were found to be 193MPa and −0.02319 for 50μm, 181MPa and −0.02001 for 100μm, and 164MPa and −0.01322 for 150μm, respectively. We found that the narrower specimen is, the longer fatigue life of Al-3%Ti is and the wider specimen is, the more susceptible to stress level fatigue life of Al-3%Ti was.

Fatigue Behavior of Aerospace Al-Cu, Al-Li and Al-Mg-Si Sheet Alloys

2015 ◽  
Vol 1099 ◽  
pp. 1-8
Author(s):  
Nikolaos D. Alexopoulos ◽  
Vangelis Migklis ◽  
Stavros K. Kourkoulis ◽  
Zaira Marioli-Riga
Keyword(s):  
Mechanical Properties ◽  
Experimental Study ◽  
Fatigue Life ◽  
High Cycle Fatigue ◽  
Endurance Limit ◽  
Fatigue Behavior ◽  
Cycle Fatigue ◽  
Constant Amplitude ◽  
6Xxx Series ◽  
Fatigue Endurance

In the present work, an experimental study was performed to characterize and analyze the tensile and constant amplitude fatigue mechanical behavior of several aluminum alloys, namely 2024 (Al-Cu), 2198 (Al-Li) and 6156 (Al-Mg-Si). Al-Li alloy was found to be superior of 2024 in the high cycle fatigue and fatigue endurance limit regimes, especially when considering specific mechanical properties. Alloy 6156 was found to have superior constant amplitude fatigue performance that the respective 6xxx series alloys; more than 15% higher endurance limit was noticed against 6061 and almost 30% higher than 6082. Alloy 6156 presented only a marginal increase in fatigue life for the HCF regime.

Tensile and Fatigue Properties of Twin-Roll-Cast AZ31 Magnesium Alloy Strips with Different Thicknesses

2021 ◽  
Vol 1034 ◽  
pp. 9-15
Author(s):  
Ye Jin Kim ◽  
Young Min Kim ◽  
Young Rae Cho ◽  
Sung Hyuk Park
Keyword(s):  
Fatigue Life ◽  
Fatigue Strength ◽  
Fatigue Resistance ◽  
High Cycle Fatigue ◽  
Tensile Elongation ◽  
Strip Thickness ◽  
Cycle Fatigue ◽  
Average Grain Size ◽  
Twin Roll Cast ◽  
Twin Roll

This study investigates the microstructure, tensile properties, and high-cycle fatigue resistance of twin-roll-cast Mg-3Al-1Zn (wt%) alloy strips with thicknesses of 1 mm, 1.5 mm, and 3 mm. The investigation results reveal that the 1-and 1.5-mm-thick strips show a fully dynamically recrystallized (DRXed) microstructure consisting of fine equiaxed DRXed grains, whereas the 3-mm-thick strip shows a partially DRXed microstructure containing very coarse elongated unDRXed grains because of the insufficient strain imposed during twin-roll casting. The inhomogeneous microstructure of the 3-mm-thick strip leads to a large deviation in its tensile elongation. The average grain size of the strips increases with increasing strip thickness, which results in reductions in both their tensile strength and their ductility because of the weakened grain-boundary hardening effect and the promoted formation of undesirable twins, respectively. The high-cycle fatigue resistance in the stress regime with finite fatigue life is similar for all three strips, but the fatigue strength with infinite fatigue life decreases from 175 MPa to 140 MPa as the strip thickness increases from 1 mm to 3 mm. The fatigue strength (FL) increases linearly with increasing yield strength (YS) according to the relationship FL = -199.5 + 2.03·YS.

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