scholarly journals Influence Of Large Non-Metallic Inclusions On Bending Fatigue Strength Hardened And Tempered Steels

2015 ◽  
Vol 15 (3) ◽  
pp. 33-40
Author(s):  
T. Lipiński ◽  
A. Wach ◽  
E. Detyna
Keyword(s):  
Fatigue Strength ◽  
Structural Steel ◽  
Treatment Options ◽  
Fatigue Tests ◽  
Relative Volume ◽  
Heat Processing ◽  
Industrial Plant ◽  
Boron Steel ◽  
Metallic Inclusions ◽  
Steel Sections

Abstract The article discusses the effect of large oxide impurities (a diameter larger than 10 μm in size) on the fatigue resistance of structural steel of high purity during rotary bending. The study was performed on 7 heats produced in an industrial plant. The heats were produced in 140 ton electric furnaces. All heats were desulfurized. The experimental material consisted of semi-finished products of high-grade, carbon structural steel with: manganese, chromium, nickel, molybdenum and boron. 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 for 120 minutes and air-cooled. The experimental variants were compared in view of the heat treatment options. Fatigue tests were performed with the use of a rotary bending machine at a frequency of 6000 cpm. The results were statistical processed and presented in graphic form. This paper discusses the results of the relative volume of large impurities, the fatigue strength for various heat processing options.

scholarly journals The Effect of Fine Non-Metallic Inclusions on the Fatigue Strength of Structural Steel

2015 ◽  
Vol 60 (1) ◽  
pp. 65-69 ◽  
Author(s):  
T. Lipiński ◽  
A. Wach
Keyword(s):  
Heat Treatment ◽  
Fatigue Strength ◽  
Structural Steel ◽  
Oxygen Converter ◽  
Treatment Options ◽  
Relative Volume ◽  
Industrial Plant ◽  
Tempering Temperature ◽  
Metallic Inclusions ◽  
Steel Sections

Abstract 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.

scholarly journals Bending fatigue strength coefficient the low carbon steel with impurities

2018 ◽  
Vol 21 (21) ◽  
pp. 20-23
Author(s):  
Tomasz Lipiński
Keyword(s):  
Fatigue Strength ◽  
Treatment Options ◽  
Low Carbon Steel ◽  
Relative Volume ◽  
Industrial Plant ◽  
Low Carbon ◽  
Tempering Temperature ◽  
Bending Fatigue ◽  
Metallic Inclusions ◽  
Steel Sections

Abstract 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.

scholarly journals Effect Of The Spacing Between Submicroscopic Oxide Impurities On The Fatigue Strength Of Structural Steel

2015 ◽  
Vol 60 (3) ◽  
pp. 2385-2390 ◽  
Author(s):  
T. Lipiński
Keyword(s):  
Heat Treatment ◽  
Structural Steel ◽  
Fatigue Resistance ◽  
Oxygen Converter ◽  
Treatment Options ◽  
Resistance Coefficient ◽  
Industrial Plant ◽  
Tempering Temperature ◽  
Metallic Inclusions ◽  
Steel Sections

AbstractThe 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 coefficientkis determined by the distance between submicroscopic non-metallic inclusions and tempering temperature.

scholarly journals The effect of the impurities spaces on the quality of structural steel working at variable loads

2020 ◽  
Vol 11 (1) ◽  
pp. 233-238
Author(s):  
Tomasz Lipiński ◽  
Robert Ulewicz
Keyword(s):  
Phase Composition ◽  
Fatigue Strength ◽  
Structural Steel ◽  
Carbon Steels ◽  
Industrial Plant ◽  
Tempering Temperature ◽  
Composition And Structure ◽  
Metallic Inclusions ◽  
Metallurgical Processes

AbstractThe quality of carbon steels working at variable loads mainly depend of microstructure, but also of impurities. The quantity and morphology of non-metallic inclusions and spaces between impurities are correlated with the content of admixtures in the alloy, while their phase composition and structure, in particular shape, dimensions and dispersion, are determined by the course of metallurgical processes. Non-metallic inclusions as impurities found in steel can affect its performance characteristics. Their impact depends not only on their quality, but also, among others, on their size and distribution in the steel volume. The literature mainly describes the results of tests on hard steels. The article discusses the results of a study investigating the effect of the number of large non-metallic inclusions (over 10 μm in size) on the fatigue strength of structural steel during rotary bending. The study was performed on 6 heats produced in an industrial plant. Fourteen heats were produced in 140 ton electric furnaces. All heats were desulfurized and refined with argon. The experimental variants were compared in view of the tempering the research steel. The fatigue strength of steel with an impurity spaces was determined during rotary bending: the results revealed that fatigue strength is determined by the impurity spaces and tempering temperature.

An Experimental Study on the Fatigue of Structural Steels with Various Welding Details

2008 ◽  
Vol 385-387 ◽  
pp. 593-596
Author(s):  
Byeong Choon Goo
Keyword(s):  
Experimental Data ◽  
Fatigue Strength ◽  
Structural Steel ◽  
Fatigue Tests ◽  
Structural Steels ◽  
Parent Material ◽  
Key Characteristics ◽  
Load Carrying ◽  
Weld Toe ◽  
Ground Load

A structural steel should satisfy various properties under varied conditions. Fatigue strength is one of them. When structural steels are used in the form of welded joints, fatigue strength is one of the key characteristics that should be considered. In this study, comprehensive fatigue tests of a structural steel with yielding strength of about 350 MPa and tensile strength of about 520 MPa were carried out. First, a lot of specimens: parent material plates, butt welded specimens with reinforcement removed, as-welded plates, plates with weld toe ground, load-carrying cruciform, non load-carrying cruciform, plates with transverse fillet welded rib, etc were prepared and tested. S-N curves for the above specimens were compared and analyzed. Secondly, some life-size rectangular beams were fabricated by welding and tested. It is found that annealing is detrimental to fatigue strength rather than beneficial. The experimental data and results may be used usefully by engineers.

Effect of Vibration during Welding on the Fatigue Strength of Structural Steel Weldments

2007 ◽  
Vol 124-126 ◽  
pp. 1329-1332 ◽  
Author(s):  
Chin Hyung Lee ◽  
Gab Chul Jang ◽  
Hyun Chan Park ◽  
Kyong Ho Chang
Keyword(s):  
Fatigue Strength ◽  
Structural Steel ◽  
Arc Welding ◽  
Mechanical Vibration ◽  
Base Material ◽  
Fatigue Tests ◽  
Steel Bridge ◽  
Flux Cored Arc Welding ◽  
Service Load ◽  
Improve Reliability

During repair welding of steel bridge under service load, vibration occurs due to the dynamic loads like wind and vehicles, etc. However, the effect of vibration during welding on the fatigue strength of weldments is not yet clearly understood. In this paper, the effect of vibration during welding on the fatigue strength of structural steel weldments was investigated in order to improve reliability in the repair welded joints of steel bridge. The base material used in this investigation was SM 490A steel of weldable grade. Flux Cored Arc Welding (FCAW) process was used to fabricate the single ‘V’ butt joints. Welding was performed on the steel under the mechanical vibration of given frequency. The applied frequency was resonant frequency. Also, weldments under no vibration during welding were prepared. Fatigue tests were conducted using a servo hydraulic controlled 50tonf capacity UTM with a frequency of 5Hz under constant amplitude loading. Effect of vibration during welding on the fatigue strength of weldments was analyzed in detail.

scholarly journals Influence of inclusions on bending fatigue strength coefficient the medium carbon steel melted in an electric furnace

2020 ◽  
Vol 26 (3) ◽  
pp. 88-91
Author(s):  
Tomasz Lipiński ◽  
Anna Wach
Keyword(s):  
Fatigue Strength ◽  
Treatment Options ◽  
Impurity Content ◽  
Medium Carbon Steel ◽  
Industrial Plant ◽  
High Grade ◽  
Medium Carbon ◽  
Strength Coefficient ◽  
Micro Cracks ◽  
Grade Steel

AbstractThe 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 high-grade 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.

scholarly journals Effect of Aqueous Environment on High Cycle and Very-High-Cycle Fatigue Behavior for a Structural Steel

2011 ◽  
Vol 462-463 ◽  
pp. 355-360
Author(s):  
You Shi Hong ◽  
Gui An Qian
Keyword(s):  
Fatigue Strength ◽  
Structural Steel ◽  
High Cycle Fatigue ◽  
Fatigue Behavior ◽  
Fatigue Crack Initiation ◽  
Fatigue Tests ◽  
Aqueous Environment ◽  
Cycle Fatigue ◽  
Very High Cycle Fatigue ◽  
Very High

In this paper, rotary bending fatigue tests for a structural steel were performed in laboratory air, fresh water and 3.5% NaCl aqueous solution, respectively, thus to investigate the influence of environmental media on the fatigue propensity of the steel, especially in high cycle and very-high-cycle fatigue regimes. The results show that the fatigue strength of the steel in water is remarkably degraded compared with the case tested in air, and that the fatigue strength in 3.5% NaCl solution is even lower than that tested in water. The fracture surfaces were examined to reveal fatigue crack initiation and propagation characteristics in air and aqueous environments.

Assessment of Fatigue Reliability of Power Transmission Gearing for Aerospace Propulsion Applications

2013 ◽  
Author(s):  
Stefano Beretta ◽  
Mauro Filippini ◽  
Pietro Luccarelli ◽  
Andrea Motta ◽  
Giuseppe Pasquero
Keyword(s):  
Fatigue Crack ◽  
Fatigue Strength ◽  
Fatigue Crack Growth ◽  
High Cycle Fatigue ◽  
Power Transmission ◽  
High Strength ◽  
Fatigue Tests ◽  
Cycle Fatigue ◽  
Bending Fatigue ◽  
Metallic Inclusions

The fatigue strength in presence of inclusions is one of the main topics for the fatigue of high strength steels, especially the case hardened ones adopted for power transmission. In this paper we analyze the fatigue strength of carburized gears in presence of inclusions in order to develop the reliability assessment of a power transmission for aerospace propulsion. The high cycle fatigue properties of a high strength carburizing steel have been experimentally determined by conducting bending fatigue tests with specimens with artificial defects and a coherent model for the assessment of fatigue crack growth thresholds by taking into account of the residual stresses due to carburizing has been developed. In parallel, the distribution of non-metallic inclusions has been estimated by carrying out high cycle fatigue tests onto cylindrical smooth specimens and by inspection of mirror polished sections of the material. Eventually, by employing a simplified finite element model of a highly loaded gear wheel, the bending fatigue strength of gear teeth and the reliability of a turbo-propeller power transmission was determined by incorporating the fatigue crack growth thresholds, the measured residual stress profiles and the statistics of extreme non-metallic inclusions into a competing risks model applied to FE discretization.

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