The Effect of Cr & Cu on the Fatigue Strength of Grey Cast Irons

2006 ◽  
Vol 306-308 ◽  
pp. 953-958
Author(s):  
Agus Suprihanto ◽  
Darmawan Harsokoesoemo ◽  
Rochim Suratman
Keyword(s):  
Tensile Strength ◽  
Fatigue Strength ◽  
High Cycle Fatigue ◽  
The Other ◽  
Cycle Fatigue ◽  
Cast Irons ◽  
Base Materials ◽  
Endurance Strength ◽  
Grey Cast ◽  
Rotating Bending

The mechanical properties of grey cast irons can be modified with alloying elements. Cr and Cu have been known as elements that can improve tensile strength of grey cast irons. The improvement of tensile strength can be influence of fatigue strength. The goal of this research is to study the effect of alloying Cr and Cu on the fatigue strength. Four materials of grey cast irons have been conducted to high cycle fatigue (HCF) testing on the rotating bending machine. The first material is grey cast irons without added Cr and Cu, and the other have added. The percentages of Cr have been added are 0,23% wt, 0,32%wt and 0,47%wt and Cu 0,6%wt to 0,7%wt. The metallography examinations and tensile test also have been conducted. The results of this research are the material has the same microstructure. The microstructures of its materials are pearlitic grey cast irons with graphite type VII, distribution A and size of graphite 3-5. The tensile, endurance and fatigue strength of materials, which added Cr and Cu significantly increasing, compared with base materials. The tensile strength rose from 191MPa to 232MPa and the endurance strength raised from 94 MPa to 110MPa. However three modified materials, which added Cr and Cu has the same effects.

scholarly journals Properties of the Fine Granular Area and Postulated Models for Its Formation during Very High Cycle Fatigue—A Review

2020 ◽  
Vol 10 (23) ◽  
pp. 8475
Author(s):  
Jan Patrick Sippel ◽  
Eberhard Kerscher
Keyword(s):  
Fatigue Strength ◽  
Crack Initiation ◽  
Crack Growth ◽  
High Performance ◽  
High Cycle Fatigue ◽  
The Other ◽  
Cycle Fatigue ◽  
Very High Cycle Fatigue ◽  
Open Questions ◽  
Very High

Understanding the mechanisms leading to very high cycle fatigue is necessary to make predictions about the behavior under various conditions and to ensure safe design over the whole lifetime of high-performance components. It is further vital for the development of possible measures to increase the very high cycle fatigue strength. This review therefore intends to give an overview of the properties of the fine granular area that have been observed so far. Furthermore, the existing models to describe the early crack initiation and crack growth within the very high cycle fatigue regime are outlined and the models are evaluated on the basis of the identified fine granular area properties. The aim is to provide an overview of the models that can already be considered refuted and to specify the respective open questions regarding the other individual models.

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 Effects of the aging state and tensile strength on the fatigue properties of 6A01 aluminum alloy

2021 ◽  
Author(s):  
BaiShan Gong ◽  
ZhenJun Zhang ◽  
QiQiang Duan ◽  
Zhan Qu ◽  
Peng Zhang ◽  
...  
Keyword(s):  
Tensile Strength ◽  
Fatigue Strength ◽  
High Cycle Fatigue ◽  
Fatigue Crack Initiation ◽  
Al Alloys ◽  
Fatigue Properties ◽  
Al Alloy ◽  
Cycle Fatigue ◽  
Peak Aging ◽  
Increased Strength

Abstract To study the effects of the aging state and tensile strength on the fatigue properties of 6A01 Al alloy, the high-cycle fatigue (HCF) experiments were carried out for different aging states. The results show that the 6A01 Al alloy with the highest tensile strength at peak-aging state can exhibit the highest fatigue strength in comparison with the overaged state and the underaged state. The main reason is that the increased strength of the 6A01 Al alloy at peak-aging state can improve the plastic deformation resistance and inhibit the fatigue crack initiation. Besides, the intermittent distribution of grain boundary precipitates at the peak-aging state is beneficial for reducing the fatigue damage. From these results, it is verified that the tensile strength plays a key role in the fatigue strength relative to the aging state for the low-strength Al alloys.

scholarly journals Fatigue Properties of Hot-Dip Galvanized AISI 1020 Normalized Steel in Tension–Compression and Tension–Tension Loading

Materials ◽  
2021 ◽  
Vol 14 (23) ◽  
pp. 7480
Author(s):  
Shatumbu Thomas Alweendo ◽  
Motoaki Morita ◽  
Kayo Hasegawa ◽  
Shinichi Motoda
Keyword(s):  
Tensile Strength ◽  
Fatigue Strength ◽  
Heat Effect ◽  
High Cycle Fatigue ◽  
Low Cycle Fatigue ◽  
Steel Substrate ◽  
Galvanized Steel ◽  
Fatigue Properties ◽  
Cycle Fatigue ◽  
Tension Loading

Since hot-dip galvanizing causes a heat effect on cold-worked steel substrate and produces a coating layer comprised of distinct phases with varying mechanical properties, the fatigue mechanism of hot-dip galvanized steel is very complex and hard to clarify. In this study, AISI 1020 steel that has been normalized to minimize susceptibility to the heat effect was used to clarify the effect of the galvanizing layer on the tensile and fatigue properties. The galvanizing layer causes a reduction in the yield point, tensile strength, and fatigue strength. The reduction in the fatigue strength was more significant in the high cycle fatigue at R = 0.5 and 0.01 and in the low cycle fatigue at R = 0.5. The galvanizing layer seems to have very little effect on the fatigue strength at R = −1.0 in the low and high cycle fatigue. Since the fatigue strengths at R = 0.01 and −1.0 in the low cycle fatigue were strongly related to the tensile strength of the substrate, the cracking of galvanized steel was different than that of non-galvanized steel. The fatigue strength of galvanized steel at R = 0.5 dropped remarkably in the low cycle fatigue in comparison to the non-galvanized steel, and many cracks clearly occurred in the galvanizing layer. The galvanizing layer reduced the fatigue strength only under tension–tension loading. We believe that the findings in this study will be useful in the fatigue design of hot-dip galvanized steel.

Bending Fatigue and Spring Back Properties of Implant Rods Made of β-Type Titanium Alloy for Spinal Fixture

2010 ◽  
Vol 89-91 ◽  
pp. 400-404 ◽  
Author(s):  
Kengo Narita ◽  
Mitsuo Niinomi ◽  
Masaaki Nakai ◽  
Toshikazu Akahori ◽  
Harumi Tsutsumi ◽  
...  
Keyword(s):  
Titanium Alloy ◽  
Fatigue Strength ◽  
High Cycle Fatigue ◽  
The Other ◽  
Cycle Fatigue ◽  
Spring Back ◽  
Bending Fatigue ◽  
Three Point Bending ◽  
Four Point Bending ◽  
Bending Fatigue Strength

Implanting a spinal fixture using metallic rods is one of the effective treatments for spinal diseases. Because cyclic bending stress is loaded on the implant rods when patients move their upper bodies in daily life, bending fatigue properties are important for the implant rod. Further, the implant rods are bended plastically into a curved shape of spine by hand in a surgical operation. In that case, keeping shape is important, namely bending spring back properties are important factors. On the other hand, a biomedical β-type titanium alloy, Ti-29Nb-13Ta-4.6Zr (mass %) alloy (TNTZ), has been developed by the authors. Currently, this alloy are investigated to be applied to the above mentioned implant rod practically. Therefore, four-point bending fatigue and three point-bending spring back properties of TNTZ subjected various heat treatments were examined in this study. TNTZ rods were subjected to solution treatment, and then some of them were subjected to aging treatment at 673 K or 723 K for 259.2 ks, followed by water quenching. Then, four-point bending fatigue and three-point bending spring back tests were carried out on TNTZ rods subjected to the various heat treatments mentioned above. The bending fatigue strength at 2.5 million cycles in the high cycle fatigue region are not much different among any TNTZ rod. However, the bending fatigue strength of the Ti-6Al-4V ELI (Ti64) rod exceeds the fatigue strengths of every TNTZ rods in both low and high cycle fatigue regions. On the other hand, the lower spring back, which is a favorable property, was obtained for some TNTZ rod than Ti64 rod.

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.

The Effect of Foreign Object Damage on Compressor Blade High Cycle Fatigue Strength

2017 ◽  
Author(s):  
Benjamin Hanschke ◽  
Thomas Klauke ◽  
Arnold Kühhorn
Keyword(s):  
Fatigue Strength ◽  
Service Sector ◽  
High Cycle Fatigue ◽  
Compressor Blade ◽  
Foreign Object ◽  
Cycle Fatigue ◽  
Stress Concentrations ◽  
Foreign Object Damage ◽  
Input Parameters ◽  
Aero Engines

For a considerable amount of time blade integrated disks (blisks) are established as a standard component of high pressure compressors (HPCs) in aero engines. Due to the steady requirement to increase the efficiency of modern HPCs, blade profiles get thinned out and aerodynamic stage loading increases. Ever since, aerofoil design has to balance structural and aerodynamic requirements. One particularity of aero engines is the possibility to ingest different kinds of debris during operation and some of those particles are hard enough to seriously damage the aerofoil. Lately, a growing number of blisk-equipped aero engines entered service and the question of foreign object damage (FOD) sensitivity relating to compressor blade high cycle fatigue (HCF) has emerged. Correct prediction of fatigue strength drop due to a FOD provides a huge chance for cost cutting in the service sector as on-wing repairs (e.g. borescope blending) are much more convenient than the replacement of whole blisks and corresponding engine strips. The aim of this paper is to identify critical FOD-areas of a modern HPC stage and to analyze the effects of stress concentrations — caused by FOD — on the fatigue strength. A process chain has been developed, that automatically creates damaged geometries, meshes the parts and analyses the fatigue strength. Amplitude frequency strength (af-strength) has been chosen as fatigue strength indicator owing to the fact, that amplitudes and frequencies of blade vibrations are commonly measured either by blade tip timing or strain gauges. Furthermore, static and dynamic stress concentrations in damaged geometries compared to the reference design were computed. A random variation of input parameters was performed, such as the radial damage position at blade leading edge and damage diameter. Based on results of the different samples, correlations of input parameters and the fatigue strength drop have been investigated. Evaluation shows a significant mode dependence of critical blade areas with a large scatter between drops in fatigue strength visible for mode to mode comparison. Keeping in mind the necessity of fast response times in the in-service sector, FOD sensitivity computations could be performed for all blade rows of the HPC — including the analysis of possible borescope blending geometries — in the design stage. Finally, the actual amplitude frequency levels (af-levels) of the modes excited during operation have to be appropriately taken into consideration. For example, a pronounced af-strength drop due to a FOD may not be critical for safe engine operations because the observed mode is excited by small af-levels during operation. Hence, the endurance ratio — a quotient of af-level and af-strength — is used as assessment criterion.

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