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1
Content available Comparing of High-Cycle Fatigue Lifetimes in Un-corroded and Corroded Piston Aluminum Alloys in Diesel Engine Applications
Azadi M., Aroo H., Azadi M., Parast M. S. A.
Archives of Foundry Engineering
|
2021
|
Vol. 21, iss. 1
89--94
EN
Diesel engine components in the combustion chamber have been exposed to cyclic loadings under environmental effects, including high temperatures and corrosive fluids. Therefore, knowing the corrosion-fatigue behavior of materials is essential for designer engineers. In this article, pure fatigue and corrosion-fatigue behaviors of the piston aluminum alloy have been experimentally investigated. For such an objective, as-cast and pre-corrosive standard samples were tested by the rotary bending fatigue machine, under 4 stress levels. Some specimens were exposed to the corrosive fluid with 0.00235 % of the sulfuric acid for 100 and 200 hours. The results showed higher weight losses for 200 hours immersion times. As another result, it could be concluded that the lifetime decreased in pre-corrosive samples for both 100 and 200 hours of the immersion time, compared to that of as-cast specimens. However, such a lifetime reduction was more significant for 200 hours of the immersion time, especially within the high-cycle fatigue regime (or lower stress levels). Under high stress levels, both pre-corrosive sample types had almost similar behaviors. The field-emission scanning electron microscopy images of specimen fracture surfaces indicated that the brittle region of the fractured surface was larger for specimens after the 200 hours of corrosion-fatigue testing than the other specimen.
2
Content available Influence of inclusions on bending fatigue strength coefficient the medium carbon steel melted in an electric furnace
Lipiński Tomasz, Wach Anna
Production Engineering Archives
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2020
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Vol. 26, Iss. 3
88--91
EN
The parameters of high-grade steel are influenced by a combination of factors, including chemical composition and production technology. The impurity content is also a key determinant of the quality of high-grade steel. Inclusions may also play an important role, subject to their type and shape. Inclusions may increase the strength of steel by inhibiting the development of micro-cracks. The analyzed material was one grade of medium-carbon structural steel. The study was performed on 6 heats produced in an industrial plant in 140 ton electric furnaces. The experimental variants were compared in view of the five heat treatment options. The results were presented to account for the correlations between the fatigue strength coefficient during rotary bending, the diameter of and spacing between impurities. The relationship between the fatigue strength and hardness of highgrade steel vs. the quotient of the diameter of impurities and the spacing between impurities was determined. The proposed equations contribute to the existing knowledge base of practices impact of impurities with various diameters and spacing between non-metallic inclusion on fatigue strength.
3
Content available remote Development of non-contact fatigue crack propagation monitoring method using air-coupled acoustic emission system
Matsuo Takuma, Hatanaka Daisuke
Engineering Transactions
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2019
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Vol. 67, iss. 2
185--198
EN
A monitoring system for fatigue crack propagation was developed using a non-contact acoustic emission (AE) monitoring system. The AE signals generated during the plane bending fatigue test were first monitored. The AE generation rate increased after approximately 0.5 of the fatigue life ratio. The maximum amplitude of the AE signals increased with a tendency similar to that of the crack propagation. The sensor sensitivities for the flat and arced surfaces were then compared. The sensitivity improved when the specimen surface was flat. The bar specimen with plane surfaces was used for the AE monitoring of the rotary bending fatigue test. From 0.715 of the fatigue life ratio, the AE generation rate increased after crack generation. The AE signals were detected at an earlier stage of the fatigue life in the flat surface specimen compared with the arc surface specimen during the rotary bending fatigue test. The detection of fatigue cracks in the rotary component at an early stage was possible using a non-contact AE monitoring system.
4
Content available Bending fatigue strength coefficient the low carbon steel with impurities
Lipiński T.
Production Engineering Archives
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2018
|
Vol. 21
20--23
EN
The article discusses the results of a study investigating the effect of the number of fine non-metallic inclusions (up to 2 μm in size) on the fatigue strength of structural steel during rotary bending. The study was performed on 7 heats produced in an industrial plant. Fourteen heats were produced in a 100 ton oxygen converter. All heats were subjected to vacuum circulation degassing. Steel sections with a diameter of 18 mm were hardened and tempered at a temperature of 200, 300, 400, 500 and 600°C. The experimental variants were compared in view of the applied melting technology and heat treatment options. The heat treatments were selected to produce heats with different microstructure of steel, from hard microstructure of tempered martensite, through sorbitol to the ductile microstructure of spheroidite. The results were presented graphically, and the fatigue strength of steel with a varied share of non-metallic inclusions was determined during rotary bending. The results revealed that fatigue strength is determined by the relative volume of fine non-metallic inclusions and tempering temperature.
5
Content available The Effect of the Diameter and Spacing Between Impurities on the Fatigue Strength Coefficient of Structural Steel
Lipiński T.
Archives of Metallurgy and Materials
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2018
|
Vol. 63, iss. 1
519--524
EN
The article discusses the effect of the diameter and spacing between impurities (size up to 2 μm) on the fatigue strength coefficient of structural steel during rotary bending. The study was performed on 21 heats produced in an industrial plant. Fourteen heats were produced in 140 ton electric furnaces, and 7 heats were performed in a 100 ton oxygen converter. All heats were desulfurized. Seven heats from electrical furnaces were refined with argon, and heats from the converter were subjected to vacuum circulation degassing. Steel sections with a diameter of 18 mm were hardened for 30 minutes from the austenitizing temperature of 880°C and tempered at a temperature of 200, 300, 400, 500 and 600°C. The experimental variants were compared in view of the applied melting technology and heat treatment options. The results were presented graphically and mathematically to account for the correlations between the fatigue strength coefficient during rotary bending, the diameter of and spacing between submicroscopic impurities. Equations for calculating the fatigue strength coefficient at each tempering temperature and a general equation for all tempering temperatures were proposed. Equations for estimating the fatigue strength coefficient based on the relative volume of submicroscopic non-metallic inclusions were also presented. The relationship between the fatigue strength and hardness of highgrade steel vs. the quotient of the diameter of impurities and the spacing between impurities, and the fatigue strength and hardness of steel vs. the relative volume of submicroscopic non-metallic impurities were determined.
6
Content available Bending fatigue strength of steel with impurities range over 2 μm
Lipiński T.
Production Engineering Archives
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2016
|
Vol. 11, No. 2
26--30
EN
The parameters of high-grade steel are influenced by a combination of factors, including chemical composition and production technology. The impurity content is also a key determinant of the quality of high-grade steel. Non-metallic inclusions are one of the factors that influence the properties in particular fatigue strength of steel. The experimental material consisted of semi-finished products of medium-carbon structural steel. The production process involved three melting technologies: steel melting in a basic arc furnace with desulfurization or desulfurization and argon refining and in a oxygen converter and the next subjected to vacuum circulation degassing. This paper discusses the results of microstructural analyses, the changes in bending fatigue strength of steel hardened and tempered at different temperatures subjected to the size proportions and distances between the impurities of structural steel.
7
Wpływ kształtu próbki na trwałość zmęczeniową przy zginaniu stopu aluminium 2024
Marcisz E.
Zeszyty Naukowe. Mechanika / Politechnika Opolska
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2015
|
z. 105
143-146
EN
The paper presents results of research carried out in 2024 aluminum alloy for bending. The present study were specimens of circular cross-section and square. Investigation carried out are used to determine the influence the shape of the specimen on in bending fatigue life. We paper presents the results of research carried out in 2024 aluminum alloy for bending.
8
Content available Analysis of impurity spaces as a percentage volume of non-metallic inclusions
Lipiński T.
Production Engineering Archives
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2015
|
Vol. 9, No. 4
10--12
EN
The parameters of high-grade steel are influenced by a combination of factors, including chemical composition and production technology. The impurity content is also a key determinant of the quality of high-grade steel. Non-metallic inclusions are one of the factors that influence the properties, in particular fatigue strength of steel. The physical and chemical reactions that occur in the process of steel melting and solidification produce non-metallic compounds and phases, referred to as inclusions. The quantity of non-metallic inclusions is correlated with the content of dopants in the alloy, while their phase composition and structure, in particular shape, dimensions and dispersion, impurity spaces are determined by the course of metallurgical processes. The experimental material consisted of semi-finished products of medium-carbon structural steel. The production process involved three melting technologies: steel melting in a basic arc furnace with: desulfurization or desulfurization and argon refining and in an oxygen converter and next subjected to vacuum circulation degassing. Billet samples were collected to analyze the content of non-metallic inclusions with the use of an optical microscope and a video inspection microscope. The application of various heat treatment parameters led to the formation of different microstructures responsible for steel hardness values. The objective of this study was to determine the influence of percentage volume non-metallic inclusions on impurity spaces.
9
Content available The Effect of Fine Non-Metallic Inclusions on the Fatigue Strength of Structural Steel
Lipiński T., Wach A.
Archives of Metallurgy and Materials
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2015
|
Vol. 60, iss. 1
65--69
EN
The article discusses the results of a study investigating the effect of the number of fine non-metallic inclusions (up to 2 µm in size) on the fatigue strength of structural steel during rotary bending. The study was performed on 21 heats produced in an industrial plant. Fourteen heats were produced in 140 ton electric furnaces, and 7 heats were performed in a 100 ton oxygen converter. All heats were desulfurized. Seven heats from electrical furnaces were refined with argon, and heats from the converter were subjected to vacuum circulation degassing. Steel sections with a diameter of 18 mm were hardened and tempered at a temperature of 200, 300, 400, 500 and 600°C. The experimental variants were compared in view of the applied melting technology and heat treatment options. The results were presented graphically, and the fatigue strength of steel with a varied share of non-metallic inclusions was determined during rotary bending. The results revealed that fatigue strength is determined by the relative volume of fine non-metallic inclusions and tempering temperature.
PL
W pracy przedstawiono wyniki badań wpływu ilości drobnych wtrąceń niemetalicznych, o wielkości do 2 µm, na wytrzymałość zmęczeniową przy zginaniu obrotowym. Badania prowadzono na 21 wytopach wyprodukowanych w warunkach przemysłowych. 14 wytopów wykonano w piecach elektrycznych o pojemności 140 ton i 7 wytopów w konwertorze tlenowym o pojemności 100 ton. Wszystkie wytopy poddawano odsiarczaniu. 7 wytopów pochodzących z pieca elektrycznego poddawano rafinacji argonem, zaś wytopy z konwertora odgazowaniu próżniowemu. Odcinki ze stali o średnicy 18 mm hartowano i odpuszczano w temperaturach: 200, 300, 400, 500 lub 600°C. Warianty badań zestawiono uwzględniając technologię wytapiania stali opcje obróbki cieplnej. Wyniki przedstawiono w graficznej postaci uwzględniającej zależności wytrzymałości zmęczeniowej przy obrotowym zginaniu z udziałem objętościowym wtrąceń niemetalicznych. Wykazano, że wytrzymałość zmęczeniowa zależy od objętości względnej drobnych wtrąceń niemetalicznych, oraz temperatury odpuszczania.
10
Content available Effect Of The Spacing Between Submicroscopic Oxide Impurities On The Fatigue Strength Of Structural Steel
Lipiński T.
Archives of Metallurgy and Materials
|
2015
|
Vol. 60, iss. 3
2385--2390
EN
The article discusses the effect of distance between submicroscopic oxide impurities (up to 2 μm in size) on the fatigue resistance coefficient of structural steel during rotary bending. The study was performed on 21 heats produced in an industrial plant. Fourteen heats were produced in 140 ton electric furnaces, and 7 heats were performed in a 100 ton oxygen converter. All heats were desulfurized. Furthermore seven heats from electrical furnaces were refined with argon, and heats from the converter were subjected to vacuum circulation degassing. Steel sections with a diameter of 18 mm were hardened from austenitizing by 30 minutes in temperature 880°C and tempered at a temperature of 200, 300, 400, 500 and 600°C. The experimental variants were compared in view of the applied melting technology and heat treatment options. The results were presented graphically and mathematically. The fatigue resistance coefficient of structural steel with the effect of spacing between submicroscopic oxide impurities was determined during rotary bending. The results revealed that fatigue resistance coefficient k is determined by the distance between submicroscopic non-metallic inclusions and tempering temperature.
PL
W pracy przedstawiono wyniki badań wpływu odległości pomiędzy submikroskopowymi zanieczyszczeniami tlenkowymi, o wielkości do 2 μm, na wskaźnik odporności na zmęczenie stali konstrukcyjnej przy zginaniu obrotowym. Badania prowadzono na 21 wytopach wyprodukowanych w warunkach przemysłowych. 14 wytopów wykonano w piecach elektrycznych o pojemności 140 ton i 7 wytopów w konwertorze tlenowym o pojemności 100 ton. Wszystkie wytopy poddawano odsiarczaniu. Dodatkowo 7 wytopów pochodzących z pieca elektrycznego poddawano rafinacji argonem, zaś wytopy z konwertora odgazowaniu próżniowemu. Odcinki ze stali o średnicy 18 mm hartowano po austenityzowaniu w czasie 30 minut z temperatury 880°C i odpuszczano w temperaturach: 200, 300, 400, 500 lub 600°C. Warianty badań zestawiono uwzględniając technologię wytapiania stali opcje obróbki cieplnej. Wyniki przedstawiono w graficznej i matematycznej postaci uwzględniającej zależności wskaźnik odporności na zmęczenie przy obrotowym zginaniu z odległości pomiędzy submikroskopowymi zanieczyszczeniami. Wykazano, że wskaźnik odporności na zmęczenie k zależy od odległości pomiędzy submikroskopowymi wtrąceniami niemetalicznymi, oraz temperatury odpuszczania.
11
Content available Apparatus for Measuring the Bending Fatigue Properties of High Performance Polyethylene Fibre
Cai G., Shi X., Yu W.
Fibres & Textiles in Eastern Europe
|
2012
|
Vol. 20, no. 4 (93)
37--40
EN
A test method for bending fatigue has been developed to determine the bending fatigue strength of fibres. This new equipment is capable of performing the bending fatigue testing of fibres under different pre-tensions, bending angles and temperatures. This article presents results from tests on single high performance polyethylene fibre (HPPE) to characterise its bending fatigue behaviour under cyclic loading and temperatures. The curve of the cyclic tension shows that the cyclic tension changes in periods during the cyclic bending process. The S-N and č-N curves indicated that the pre-tension and bending angle had great influences on the bending fatigue life of HPPE fibre. A CCD camera was utilised to allow observation of the bending fatigue fracture morphology of the fibre. It showed the fracture mechanism of the HPPE fibres. The bending fatigue life of HPPE fibre was tested at different temperatures to show that its bending fatigue strength is strongly influenced by the temperature.
PL
Opracowano metodę oceny wytrzymałości zmęczeniowej włókien polietylenowych przy zginaniu. Przewidziano możliwość badania włókien przy rożnym obciążeniu wstępnym, kącie zginania i temperaturze. Przeprowadzono próby badania włókien polietylenowych w różnych temperaturach i przy rożnym kącie zginania. Stwierdzono, że naprężenie zginające zmienia się okresowo podczas cyklicznego procesu zginania. Stwierdzono również, że wstępne naprężenie oraz kąt zginania mają istotny wpływ na wytrzymałość zmęczeniową badanych włókien. Kamerę CCD zastosowano dla obserwacji morfologii przełomu zmęczeniowego włókien, pozwalającego na identyfikację mechanizmu przełomu. Stwierdzono wyraźny wpływ temperatury, w której przeprowadzano próby.
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