High Cycle Fatigue Parameters of High Chromium Steel

2011 ◽  
Vol 488-489 ◽  
pp. 299-302
Author(s):  
Matej Drobne ◽  
Peter Göncz ◽  
Srečko Glodež
Keyword(s):  
Mechanical Properties ◽  
Fatigue Strength ◽  
High Cycle Fatigue ◽  
Research Work ◽  
Chromium Steel ◽  
Multiaxial Fatigue ◽  
Cycle Fatigue ◽  
High Chromium ◽  
Testing Procedures

The determination of monotonic mechanical properties and high cycle fatigue parameters of high chromium steel (HCS) is presented. The monotonic mechanical properties (ultimate compressive and ultimate tensile strength) are determined using standardized testing procedures according to DIN 50125 standard. The high cycle fatigue parameters are determined using uniaxial fatigue test where the tests specimens are loaded with pure pulsating compression load (load ratio R=0 in compression) at different load levels. Therefore, a typical S-N curve and appropriate fatigue parameters (fatigue strength coefficient sf’ and fatigue strength exponent b) are determined. The experimental results determined in this study can serve as a basis for the determination of service life of rolls using stress-life approach. However, a few guidelines for the further research work considering increased temperatures and multiaxial fatigue are given in the conclusions of this study.

scholarly journals On the variability in static and cyclic mechanical properties of extruded 7075-T6 aluminum alloy

2021 ◽  
Author(s):  
Matteo Benedetti ◽  
Cinzia Menapace ◽  
Vigilio Fontanari ◽  
Ciro Santus
Keyword(s):  
Mechanical Properties ◽  
Tensile Strength ◽  
Fatigue Strength ◽  
High Cycle Fatigue ◽  
Tensile Tests ◽  
Total Elongation ◽  
Extrusion Ratio ◽  
Cycle Fatigue ◽  
Hardness Tests ◽  
Fatigue Endurance

The present paper investigates the variability in the static and cyclic properties of two nominally identical supplies of the aeronautical Al grade 7075-T6. Samples were extracted from extruded bars of 15 mm and 60 mm diameter and with slightly different chemical composition. Noticeable differences were found in tensile strength, total elongation, low- and high-cycle fatigue strength, despite the nearly identical hardness value. The diverse mechanical behavior has been imputed to different extrusion ratio and therefore work hardening along with a more or less fine distribution of precipitates and dispersoids. The high-cycle fatigue strength was found to be in direct correlation with the monotonic yield strength and the size of the largest intermetallic precipitate. A simple equation based on Murakami sqrt(area) parameter is proposed to predict the fatigue endurance. Tensile tests and microstructural analyses are recommended instead of conventional hardness tests to have a tighter quality control on the mechanical properties of semifinished products.

scholarly journals Validation of Multiaxial Fatigue Strength Criteria on Specimens from Structural Steel in the High-Cycle Fatigue Region

Materials ◽  
2020 ◽  
Vol 14 (1) ◽  
pp. 116
Author(s):  
František Fojtík ◽  
Jan Papuga ◽  
Martin Fusek ◽  
Radim Halama
Keyword(s):  
Fatigue Strength ◽  
Structural Steel ◽  
High Cycle Fatigue ◽  
Fatigue Loading ◽  
Multiaxial Fatigue ◽  
Experimental Results ◽  
Prediction Methods ◽  
Cycle Fatigue ◽  
Strength Criteria

The paper describes results of fatigue strength estimates by selected multiaxial fatigue strength criteria in the region of high-cycle fatigue, and compares them with own experimental results obtained on hollow specimens made from ČSN 41 1523 structural steel. The specimens were loaded by various combinations of load channels comprising push–pull, torsion, bending and inner and outer pressures. The prediction methods were validated on fatigue strengths at seven different numbers of cycles spanning from 100,000 to 10,000,000 cycles. No substantial deviation of results based on the selected lifetime was observed. The PCRN method and the QCP method provide best results compared with other assessed methods. The results of the MMP criterion that allows users to evaluate the multiaxial fatigue loading quickly are also of interest because the method provides results only slightly worse than the two best performing solutions.

Fracture Toughness and Fatigue Crack Growth Characteristics of UFG Microalloyed and IF Steels Processed by Critical Phase Control Multiaxial Forging

2021 ◽  
Vol 1016 ◽  
pp. 481-486
Author(s):  
Sumit Ghosh ◽  
Suhrit Mula ◽  
Mahesh Somani ◽  
Jukka Kömi
Keyword(s):  
Mechanical Properties ◽  
Fracture Toughness ◽  
Fatigue Strength ◽  
Yield Strength ◽  
High Cycle Fatigue ◽  
Fracture Mechanisms ◽  
Interstitial Free ◽  
If Steel ◽  
Cycle Fatigue ◽  
Structural Applications

The aim of the current study is to design multiaxial forging (MAF) schedules in order to achieve submicron-grained (<1μm) structure in a microalloyed (MA) steel as well as an interstitial-free (IF) steel, which could impart a good combination of yield strength and tensile ductility. At the same time, an effort has been made to evaluate the fracture toughness characteristics by conducting 3-point bend tests and computing the KQ, Kee and J-integral values of ultrafine grained (UFG) samples and correlating them with the microstructure, besides evaluating the other mechanical properties. Fatigue strength in the high cycle fatigue (HCF) regime were also investigated and fracture mechanisms analyzed and comparison established between differently processed samples. The microstructural analysis was performed using transmission electron microscopy (TEM) and Electron backscatter diffraction (EBSD) and results corroborated with the mechanical properties. Superior combinations of yield strength (YS), ductility (% El.), fracture toughness (Kee) and high cycle fatigue strength (σf) were obtained under certain conditions, i.e., i) MA steel: intercritical (α+γ) phase regime (~Ar1) controlled and 15-cycle multiaxially forged (MAFed) (YS=1027MPa, %El.=8.3%, σf=355MPa and Kee=90MPa√m), and ii) IF steel: ferritic region (<Ar1) controlled 18-cycle MAFed (YS=881MPa, %El.=11.2%, σf=255MPa and Kee=97MPa√m). In the case of MA steel, an enhancement of the fatigue and fracture toughness properties can be ascertained following the formation of uniformly distributed nanosized fragmented cementite (Fe3C) particles (~35nm size) present in the submicron sized (average ~280nm size) ferritic microstructure. In contrast, in the case of IF steel, this is ascribed to the development of submicron sized ferrite grains (average ~320nm) along with a high density of dislocation substructures. These fine dislocation cells/substructures along with the nanosized Fe3C particles could effectively block the initiation and propagation of cracks and thereby enhance the fatigue endurance and fracture toughness of the steel. Superior fracture toughness along with high mechanical properties in submicron-grained condition render the two steels highly useful for high-strength structural applications.

scholarly journals On the determination of the bending fatigue strength in and above the very high cycle fatigue regime of shot-peened gears

2021 ◽  
Author(s):  
D. Fuchs ◽  
S. Schurer ◽  
T. Tobie ◽  
K. Stahl
Keyword(s):  
Fatigue Strength ◽  
High Cycle Fatigue ◽  
Load Carrying Capacity ◽  
Cycle Fatigue ◽  
Bending Fatigue ◽  
Very High Cycle Fatigue ◽  
Bending Load ◽  
Load Carrying ◽  
Bending Fatigue Strength ◽  
Very High

AbstractDemands on modern gearboxes are constantly increasing, for example to comply with lightweight design goals or new CO2 thresholds. Normally, to increase performance requires making gearboxes and powertrains more robust. However, this increases the weight of a standard gearbox. The two trends therefore seem contradictory. To satisfy both of these goals, gears in gearboxes can be shot-peened to introduce high compressive residual stresses and improve their bending fatigue strength. To determine a gear’s tooth root bending fatigue strength, experiments are conducted up to a defined number of load cycles in the high cycle fatigue range. However, investigations of shot-peened gears have revealed tooth root fracture damage initiated at non-metallic inclusions in and above the very high cycle fatigue range. This means that a further reduction in bending load carrying capacity has to be expected at higher load cycles, something which is not covered under current standard testing conditions. The question is whether there is a significant decrease in the bending load carrying capacity and, also, if pulsating tests conducted at higher load cycles—or even tests on the FZG back-to-back test rig—are necessary to determine a proper endurance fatigue limit for shot-peened gears. This paper examines these questions.

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