Pulsating Fatigue Properties of Stainless Steels

2006 ◽  
Vol 306-308 ◽  
pp. 103-108
Author(s):  
Shinichi Nishida ◽  
Nobusuke Hattori ◽  
Takamitsu Shimizu ◽  
Priyo Tri Iswanto
Keyword(s):  
Fatigue Strength ◽  
Fatigue Limit ◽  
Stainless Steels ◽  
Mean Value ◽  
Heat Treatment Condition ◽  
Fatigue Properties ◽  
Static Mechanical ◽  
The Mean ◽  
Micro Structures ◽  
Static Mechanical Properties

The object in this study is to investigate the pulsating fatigue properties of ferritic and martenstic stainless steels using replica method. The main results obtained in this test are as follows; two kinds of ferrritic stainless steels show the same fatigue strength, even if there is difference in micro-structures due to charge of heat treatment condition. In addition, the fatigue limit of martenstic stainless steel shows higher than that of ferritic one by 230%. It is considered that the static mechanical properties relate to the mean value of micro-structures and the fatigue strength relates to the weakest portion of structures. In addition, the ratio between fatigue limit and hardness number becomes considerably smaller than that of conventional structural steels.

scholarly journals Investigation of Changes in Fatigue Damage Caused by Mean Load under Block Loading Conditions

Materials ◽  
2021 ◽  
Vol 14 (11) ◽  
pp. 2738
Author(s):  
Roland Pawliczek ◽  
Tadeusz Lagoda
Keyword(s):  
Fatigue Life ◽  
Fatigue Damage ◽  
Strain Curve ◽  
Mean Value ◽  
Fatigue Properties ◽  
Stress Strain ◽  
Reference Case ◽  
Block Loading ◽  
The Mean ◽  
Mean Strain

The literature in the area of material fatigue indicates that the fatigue properties may change with the number of cycles. Researchers recommend taking this into account in fatigue life calculation algorithms. The results of simulation research presented in this paper relate to an algorithm for estimating the fatigue life of specimens subjected to block loading with a nonzero mean value. The problem of block loads using a novel calculation model is presented in this paper. The model takes into account the change in stress–strain curve parameters caused by mean strain. Simulation tests were performed for generated triangular waveforms of strains, where load blocks with changed mean strain values were applied. During the analysis, the degree of fatigue damage was compared. The results of calculations obtained for standard values of stress–strain parameters (for symmetric loads) and those determined, taking into account changes in the curve parameters, are compared and presented in this paper. It is shown that by neglecting the effect of the mean strain value on the K′ and n′ parameters and by considering only the parameters of the cyclic deformation curve for εm = 0 (symmetric loads), the ratio of the total degree of fatigue damage varies from 10% for εa = 0.2% to 3.5% for εa = 0.6%. The largest differences in the calculation for ratios of the partial degrees of fatigue damage were observed in relation to the reference case for the sequence of block n3, where εm = 0.4%. The simulation results show that higher mean strains change the properties of the material, and in such cases, it is necessary to take into account the influence of the mean value on the material response under block loads.

Effect of Plastic Working on Fatigue Properties of Ti-6Al-4V Alloy with Notch

2005 ◽  
Vol 297-300 ◽  
pp. 2513-2518
Author(s):  
Nobusuke Hattori ◽  
Shinichi Nishida ◽  
Masahiro Hara ◽  
Sun Young Son
Keyword(s):  
Fatigue Strength ◽  
Fatigue Limit ◽  
Work Hardening ◽  
Fatigue Cracks ◽  
Fatigue Properties ◽  
Plastic Working

This study is focused to the effects of plastic working on the fatigue strength of Ti-6Al-4V alloy with notch. In general, the fatigue strength of plastic worked specimen is higher than that of non-worked one. However, the potential of hardening ability of Ti-6Al-4V alloy is very limited. Accordingly, the effect of work hardening on fatigue strength about this material is very small. In addition, the surface of the worked part becomes rougher with increasing plastic deformed value and the fatigue cracks initiate at this part. Consequently, the fatigue limit of the plastic worked specimen is lower than that of the non-plastic-worked one.

FATIGUE PROPERTIES OF AUTOMOBILE HIGH-STRENGTH BOLTS

2008 ◽  
Vol 22 (31n32) ◽  
pp. 5539-5544 ◽  
Author(s):  
CONGLING ZHOU ◽  
SHIN-ICHI NISHIDA ◽  
NOBUSUKE HATTORI
Keyword(s):  
Tensile Strength ◽  
Fatigue Strength ◽  
Residual Stresses ◽  
Stress Level ◽  
High Strength ◽  
Fatigue Properties ◽  
Screw Thread ◽  
Mean Stress ◽  
Stress Levels ◽  
The Mean

This study is focused on the fatigue properties of automobile high-strength bolts, including the effect of mean stress level, pre-processing schedule and the residual stresses. And the mean stress levels are 0.3, 0.5 and 0.7 times to the tensile strength (σ B ) of the material respectively. The main results obtained are as follows: 1) the fatigue strength increases under the mean stress loading, but the differences between the loading levels are not so evident; 2) most of the cases in this study are broken from the bottom of the screw thread, and the crack initiated from the impurities.

Investigation of Fatigue Properties for Welded Aluminum Forging Preforms

2008 ◽  
Author(s):  
W. P. Harris ◽  
J. P. Domblesky
Keyword(s):  
Dynamic Properties ◽  
Weld Zone ◽  
Fatigue Properties ◽  
Test Machine ◽  
Forged Parts ◽  
Aluminum Forging ◽  
Static Mechanical ◽  
Potential Benefits ◽  
Metallurgical Evaluation ◽  
Static Mechanical Properties

While welded forging preforms offer potential benefits for producing forged parts, work to date has mainly been concentrated on assessing static mechanical properties. As dynamic properties are an important consideration, the objective in the current study was to assess the high cycle fatigue properties of 6061-T6 aluminum forging performs which were prepared using friction welding. Monolithic and friction welded specimens were prepared and hot worked using a laboratory press. Fatigue data was then generated using a rotating beam test machine and a metallurgical evaluation of the weld zone performed. The results showed that, in general, forged preforms demonstrated superior fatigue life when compared to as-friction welded preforms in the same temper condition. Fatigue performance was also found to be comparable to that obtained from monolithic forging preforms which had an identical processing history.

Effect of Plating Thickness on Fatigue Strength of Galvanized Steel

2020 ◽  
Vol 841 ◽  
pp. 3-8
Author(s):  
Kayo Hasegawa ◽  
Tatsuo Hayashi ◽  
Motoaki Morita ◽  
Shinichi Motoda
Keyword(s):  
Tensile Strength ◽  
Fatigue Strength ◽  
Fatigue Limit ◽  
Main Crack ◽  
Immersion Time ◽  
Room Temperature ◽  
Columnar Structure ◽  
Galvanized Steel ◽  
Fatigue Properties ◽  
Plating Layer

Effect of the plating thicknesses on tensile and fatigue properties of hot-dip galvanized steel at room temperature was evaluated. The galvanized steel with thickness of 100 μm and 200 μm were prepared. Both microstructures of η-phase and δ1-phase were similar with each other. In the comparison with the galvanized steel with thickness of 100 μm, the microstructure of ζ-phase for the galvanized steel with thickness of 200 μm was blunt columnar structure due to long immersion time. Tensile and fatigue strengths for a galvanized steel are sensitive to the microstructure of the galvanized layer. The tensile strength and the strength of fatigue limit for the galvanized steel with thickness of 200 μm were smaller than that of 100 μm. In the galvanized steel with thickness of 200 μm, the peeling at plating layer easily occurred. The exfoliated sites have the potential to become subcracks. As the result, the main crack may propagate at early cycles.

Fatigue Properties of Austenitic Stainless Steels with Different Nitrogen

2004 ◽  
Vol 261-263 ◽  
pp. 1215-1220 ◽  
Author(s):  
Nobusuke Hattori ◽  
S. Nishida
Keyword(s):  
Fatigue Strength ◽  
Stainless Steels ◽  
Stress Amplitude ◽  
Austenitic Stainless Steels ◽  
Fatigue Tests ◽  
The Other ◽  
Fatigue Properties ◽  
Transformation Ratio ◽  
Other Hand ◽  
Knee Point

The fatigue properties of austenitic stainless steels become inevitably important when using in structural materials. The authors have performed fatigue tests to investigate the effect of nitrogen content on fatigue properties of typical austenitic stainless steels (SUS304) and two kinds of nitrogen-contained SUS304 (SUS304N and YUS170). The main results obtained in this study are as follows; (1) The knee point in S-N curves exists for SUS304 and SUS304N, but does not exist for YUS170. (2) The fatigue limit of SUS304N is higher than that of SUS304. On the other hand, the fatigue strength by 107 cycles of YUS170 is lower than those of SUS304 and SUS304N. (3) For SUS304, the transformation ratio increases with increase in stress amplitude. On the other hand, the transformation ratio of SUS304N is very small and that of YUS170 remains essentially zero.

High Cycle Fatigue Properties of Modified 9Cr-1Mo Steel at Elevated Temperatures

2012 ◽  
Author(s):  
Yoshiaki Matsumori ◽  
Jumpei Nemoto ◽  
Yuji Ichikawa ◽  
Isamu Nonaka ◽  
Hideo Miura
Keyword(s):  
Fatigue Strength ◽  
Fatigue Limit ◽  
Room Temperature ◽  
Structural Reliability ◽  
High Cycle Fatigue ◽  
Elevated Temperatures ◽  
Fatigue Behavior ◽  
Cyclic Softening ◽  
Fatigue Properties ◽  
Cycle Fatigue

Since high-cycle fatigue loads is applied to the pipes in various energy and chemical plants due to the vibration and frequent temperature change of fluid in the pipes, the high-cycle fatigue behavior of the alloys used for pipes should be understood quantitatively in the structural reliability design of the pipes. The purpose of this study, therefore, is to clarify the high-cycle fatigue strength and fracture mechanism of the modified 9Cr-1Mo steel at temperatures higher than 400°C. This material is one of the effective candidates for the pipes in fast breeder demonstration reactor systems. A rotating bending fatigue test was applied to samples at 50 Hz in air. The stress waveform was sinusoidal and the stress ratio was fixed at −1. The fatigue limit was observed at room temperature and it was about 420 MPa. This value was lower than the 0.2% proof stress of this alloy by about 60 MPa. This decrease can be attributed to the cyclic softening of this material. The limited cycles at knee point was about 8×105 cycles. All fracture was initiated from a single surface crack and no inclusion-induced fracture was observed in the fracture surface by SEM. Thus, the high-cycle fatigue design based on the fatigue limit may be applicable to the modified 9Cr-1Mo steel at room temperature. The fatigue limit of about 350 MPa was also observed at 400°C, and it appeared at about 107 cycles, while it appeared at around 106 cycles at room temperature. Thus, it was confirmed that the fatigue strength of this alloy decrease with temperature. However, the fatigue limit didn’t appear at 550°C up to 108 cycles. The fatigue limit may disappear in this alloy at 550°C. It is very important, therefore, to evaluate the ultra-high cycle fatigue strength of this alloy at temperatures higher than 400°C.

scholarly journals ANALISIS KERUSAKAN GERBONG DATAR “PPCW”42 TON AKIBAT BEBAN OPERASI

2016 ◽  
Vol 16 (1) ◽  
Author(s):  
Anwar . ◽  
M. Gozali
Keyword(s):  
Fatigue Strength ◽  
Real Time ◽  
Fatigue Limit ◽  
Frame Structures ◽  
Critical Area ◽  
The Mean ◽  
Diagram Approach ◽  
Mean Stresses

Several units of PPCW wagons capacity of 42 ton are used for the cement transportation, cracked on the under frame structures. To determine the cause of the cracks, the investigation was conducted by measuring the stress that occurs when the wagons operation.Results of the investigations are the mean stresses and amplitude stresses measured in real-time in the various road conditions, and then be analyzed using fatigue limit diagram approach to get fatigue strength of the wagon structure. The analysis result shows that the stresses at several points of the wagon structure under the operational loads are in the critical area or is above the fatigue limit diagram. This is the cause of the failure of the under frame of the PPCW wagon structure.AbstrakBeberapa unit gerbong PPCW kapasitas 42 ton yang digunakan untuk pengangkutan semen, mengalami retak pada bagian rangka bawah. Untuk menegetahui penyebab terjadinya retak tersebut, dilakukan penelitian dengan cara mengukur tegangan yang terjadi pada saat gerbong beroperasi.Hasil penelitian berupa besaran tegangan rata-rata dan tegangan amplitudo yang diukur secara real-time pada berbagai kondisi jalan, dianalisis dengan menggunakan pendekatan diagram batas lelah. Hasil analisis menunjukkan bahwa tegangan pada beberapa titik berada pada daerah kritis atau diagram garis batas lelah. Hal ini merupakan penyebab terjadinya kerusakan struktur rangka bawah gerbong PPCW.Keywords : PPCW wagon, stresses, fatigue limit diagram.

High Cycle Fatigue Properties of Aluminium Foams

1998 ◽  
Vol 521 ◽  
Author(s):  
B. E. Zettl ◽  
S. E. Stanzl-Tschegg ◽  
R. Gradinger ◽  
H. P. Degischer
Keyword(s):  
Mechanical Properties ◽  
Fatigue Properties ◽  
Fatigue Lifetime ◽  
Lifetime Measurements ◽  
Bending Tests ◽  
Testing Method ◽  
Quantitative Image ◽  
Static Mechanical ◽  
Cast Alloys ◽  
Static Mechanical Properties

ABSTRACTFatigue lifetime measurements have been performed on foamed Al-Mg-Si wrought alloys and Al-Si cast alloys in the high cycle range using an ultrasonic resonance testing method. The porous structure of the material is described by quantitative image analysis of optical micrographs and non destructively by X-ray computer tomography. The static mechanical properties as determined by tensile, compression and bending tests in earlier studies are used for material characterisation in this paper. The evaluation of the stress strain curves is specified for porous structures to obtain the stiffness and the plateau strength. The influence of the surface skin on the mechanical properties as well as on oscillation behaviour during lifetime measurements was studied.

scholarly journals The effect of virgin nylon addition into recycled nylon on the fatigue strength of thermoplastic nylon denture base

2020 ◽  
Vol 32 (1) ◽  
pp. 68
Author(s):  
Siti Wahyuni ◽  
Jeewena Ravichanthiran
Keyword(s):  
Fatigue Strength ◽  
Injection Molding ◽  
Mean Value ◽  
Laboratory Research ◽  
Injection Molding Process ◽  
Test Results ◽  
Molding Process ◽  
Denture Base ◽  
Experimental Laboratory ◽  
The Mean

Introduction: Thermoplastic nylon denture base is processed through injection molding process. This manipulation technique produces non-biodegradable nylon wastes which have to be recycled. Recycling of nylon wastes is feasible due to the linear molecular structure of thermoplastic nylon. This study aimed to know the effect of adding virgin nylon into recycled nylon on the fatigue strength of thermoplastic nylon denture base. Methods: This research was experimental laboratory research using 27 samples of thermoplastic nylon with three different groups (100% virgin nylon, 100% recycled nylon and combination of 60% of virgin nylon with 40% of recycled nylon) using injection molding technique. The test results were analyzed using one-way ANOVA test to know the differences in the mean value of the fatigue strength of each group and LSD test to know the effect of adding 60% of virgin nylon into 40% of recycled nylon. Resuts: Results showed significant results (p < 0,05), as well as LSD test that showed there is effect of adding 60% of virgin nylon into 40% of recycled nylon on the fatigue strength of thermoplastic nylon denture base. Conclusion: The combination of 60% of virgin nylon with 40% of recycled nylon showed higher fatigue strength than the recycled nylon.

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