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In this paper we give a presentation of the recently developed approaches concerned of the rate of oxidation the Arema steel at high-temperature in first stage of this process. The comparison analysis was performed on the basis of the... more
In this paper we give a presentation of the recently developed approaches concerned of the rate of oxidation the Arema steel at high-temperature in first stage of this process. The comparison analysis was performed on the basis of the experimental results of oxidation of cylindrical specimens made of above steel. The experiment was carried out in chamber furnace on series of specimen with dimension Φ = 20 , l=30 mm. The specimens were oxidized at 1000 °C for 10 - 2280 minutes in air and then quenched in silica sand, afterwards were measured and weighed both with and without of scale. The analysis reveals that for longer oxidation time than one hour influence of linear dependence on parabolic growth of scale can be neglected.
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The corrosion behavior of four valve steels (X33CrNiMn23-8, X50CrMnNiNbN21-9, X53CrMnNiN20-8 and X55CrMnNiN20-8) in combustion gases of fuel oil, containing different bio-component concentrations of (5 and 10 wt. %) has been studied under... more
The corrosion behavior of four valve steels (X33CrNiMn23-8, X50CrMnNiNbN21-9, X53CrMnNiN20-8 and X55CrMnNiN20-8) in combustion gases of fuel oil, containing different bio-component concentrations of (5 and 10 wt. %) has been studied under thermal shock conditions. It has been found that the addition of bio-components to the fuel oil decreases the corrosion resistance of all steels under investigation, this effect being the stronger, the higher was the concentration of bio-component addition. It has been shown, that in spite of bio-component addition, the X33CrNiMn23-8 steel containing the highest chromium concentration, behaved much better than three remaining steels due to the formation of the highly protective chromia scale.
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The paper presents an instance of a failure of the casing of a press used to make hexagonal clamps on tubes used in power engineering. The failure occurred during the press operation. The results of microscopic investigations of the... more
The paper presents an instance of a failure of the casing of a press used to make hexagonal clamps on tubes used in power engineering. The failure occurred during the press operation. The results of microscopic investigations of the cracked area show that the crack was initiated by excessive accumulation of sulfide inclusions with an unfavourable banded structure that formed in the steel. An EDS analysis identified MnS involved in the crack mechanism.Moreover, an FEM simulation of the pressure distribution and an annulus model of axial loading were used to analyse the stress and strain values arising in the press casing under compression. It was found that normal compressive stresses in direction Z were much larger in the region where the crack occurred, which means that the press casing mechanical manufacturing process creates the largest stresses in the fillet radius area. On the other hand, the effect of sulphide inclusions in the material were also considered as a cause of failure.It is concluded that both these factors – equivalent stresses and the high level of sulphide inclusions in the steel structure have an impact on the press casing failure.
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In this work will be presented the results of influence of heat-resisting insulated ceramic layers on increase of durability of high-heat loaded engine valves made of valve steel grade H10S2M according to Polish Standard. The inlet valves... more
In this work will be presented the results of influence of heat-resisting insulated ceramic layers on increase of durability of high-heat loaded engine valves made of valve steel grade H10S2M according to Polish Standard. The inlet valves and stems of outlet valves heated up to 400 o C are produced from the heat-treated steels, e.g. H10S2M acc. to PN, containing inter alia c.a. 9.5% wt. Cr, 2.5%wt. Si and 0.8% Mo, whereas heads of outlet valve are heated sometimes up to 900 o C and made of austenitic steels contains c.a. 14% Cr, 14% Ni and also other elements c.a. 2.5% W and 0.3% Mo. The valves used as samples were covered by ceramic layers and annealed in electrical chamber furnace. The isothermal process of annealing was carried out at 1100, 1060, 1020, 980 and 940°C in the electrical chamber furnace at the gravitational flow of air. On the basis of conducted experiment it can be stated, that applied ceramic layers ensures good protection of steel surfaces against of the influence...
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The corrosion behavior of four grades of valves steels i.e.; X33CrNiMn23-8, X50CrMnNiNbN21-9, X33CrNiMnN23-8, X50CrMnNiNbN21-8, X53CrMnNiN20-8 and X55CrMnNiN20-8 in combustion gases of fuel oil with different quantities of FAME (Fatty... more
The corrosion behavior of four grades of valves steels i.e.; X33CrNiMn23-8, X50CrMnNiNbN21-9, X33CrNiMnN23-8, X50CrMnNiNbN21-8, X53CrMnNiN20-8 and X55CrMnNiN20-8 in combustion gases of fuel oil with different quantities of FAME (Fatty Acid Methyl Esters) has been studied. In this work, the results of kinetic oxidation of above mentioned valve steels in combustion gases from diesel engine with 5, 10, 20% [v/v] of FAME are presented. It has been found that increase of FAME up to 20% volume percentage to the fuel oil decreases corrosion resistance of tested steels. The corrosion tests have been performed gravimetrically under thermal shock conditions by heating of specimens from room temperature up to 1173 K. After heating at 1173 K for two hours, specimens were quenching at room temperature for 20 minutes and again heated. This experiment simulated valves work conditions of highly thermal loaded combustion engines.
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INTRODUCTION Full-thickness rotator cuff tear is one of the most common conditions affecting the shoulder joint. The clinical outcomes of rotator cuff repair have been promising, although structural failure after repair is a wellknown and... more
INTRODUCTION Full-thickness rotator cuff tear is one of the most common conditions affecting the shoulder joint. The clinical outcomes of rotator cuff repair have been promising, although structural failure after repair is a wellknown and frequent complication. With various advanced repair techniques, there are biologic trials to enhance tendon-to-bone healing, but the results have not been successful as expected. Fatty degeneration of rotator cuff muscle after tendon tear is a well-known phenomenon, and this is closely related with outcome after repair even in integrity. Considering that our principal goal of rotator cuff repair is restore the insertion point of muscle to work as a motor, even excellent integrity would be worthless when complete muscle degeneration has been taken place. In these respects, we intended to regenerate the muscle, by way of using adipose-derived stem cells (ADSCs). Therefore, the purpose of this study was to evaluate effect of ADSCs after repair of suba...
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The corrosion resistance of three grades of valve steels (X33CrNiMn23-8, X50CrMnNiNbN21-9, X53CrMnNiN20-8) in combustion gases of propane-butane (LPG) under thermal shock conditions has been studied. It was stated that X33CrNiMn23-8... more
The corrosion resistance of three grades of valve steels (X33CrNiMn23-8, X50CrMnNiNbN21-9, X53CrMnNiN20-8) in combustion gases of propane-butane (LPG) under thermal shock conditions has been studied. It was stated that X33CrNiMn23-8 steel, containing highest concentration of chromium and nickel and also the lowest of manganese concentration, showed the best corrosion resistance in comparison to another tested steels. The worse corrosion resistance in combustion gases of propane-butane (LPG) was stated in reference to X50CrMnNiNbN21-9 and X53CrMnNiN20-8 valve steels containing lower chromium and nickel concentrations.
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The corrosion resistance of widely used X50CrMnNiNbN21-9 high-alloyed austenite valve steel in three different combustion gases have been compared.The comparison was performed on the basis of results of kinetic corrosion of the tested... more
The corrosion resistance of widely used X50CrMnNiNbN21-9 high-alloyed austenite valve steel in three different combustion gases have been compared.The comparison was performed on the basis of results of kinetic corrosion of the tested steel in combustion gases from propane-butane, gasoline with 5 and 10% of ethanol additives (v/v) and fuel oil with 5 and 10% of FAME additives (v/v). The corrosion test was performed gravimetrically under thermal shock conditions by heating samples of the test steels from room temperature up to 1173 K in exhaust gases from a combustion engine, and holding them at this temperature for 2 hrs. and then cooling at room temperature for about 25 min. Then the same thermal shock was repeated and after every 10 to 20 such cycles the mass of the samples were measured. This experiment simulated the working conditions of a highly thermal loaded exhaust valves in spark or self-ignited combustion engines. The analysis performed shows that the corrosion resistance ...
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ABSTRACT The influence of yttrium, as well as the thickness of chromium layers sputter-deposited on valve steels (X33CrNiMn23-8, X50CrMnNiNbN21-9, X53CrMnNiN20-8 and X55CrMnNiN20-8) on their oxidation resistance, was studied under... more
ABSTRACT The influence of yttrium, as well as the thickness of chromium layers sputter-deposited on valve steels (X33CrNiMn23-8, X50CrMnNiNbN21-9, X53CrMnNiN20-8 and X55CrMnNiN20-8) on their oxidation resistance, was studied under isothermal (900°C) and thermal shock conditions (25–900°C). We found out that chromium layers with higher thickness increase oxidation resistance only in the case of valve steels with lower chromium content. On the other hand, a modification made by deposition of small yttrium additions on the surface of coatings significantly increases oxidation resistance of protected steels. This is due to the formation of highly protective chromia scale or chromium-containing spinel oxide phases during oxidation, instead of non-protective iron oxides. Additionally, 100-h corrosion tests were carried out on valves covered by chromium coatings in real working conditions of an internal combustion engine. The obtained positive results strongly support the idea of tailoring a new generation of inexpensive, thin coatings for engine valve protection. Graphical Abstract
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The paper presents an instance of a failure of the casing of a press used to make hexagonal clamps on tubes used in power engineering. The failure occurred during the press operation. The results of microscopic investigations of the... more
The paper presents an instance of a failure of the casing of a press used to make hexagonal clamps on tubes used in power engineering. The failure occurred during the press operation. The results of microscopic investigations of the cracked area show that the crack was initiated by excessive accumulation of sulfide inclusions with an unfavourable banded structure that formed in the steel. An EDS analysis identified MnS involved in the crack mechanism.Moreover, an FEM simulation of the pressure distribution and an annulus model of axial loading were used to analyse the stress and strain values arising in the press casing under compression. It was found that normal compressive stresses in direction Z were much larger in the region where the crack occurred, which means that the press casing mechanical manufacturing process creates the largest stresses in the fillet radius area. On the other hand, the effect of sulphide inclusions in the material were also considered as a cause of failure.It is concluded that both these factors – equivalent stresses and the high level of sulphide inclusions in the steel structure have an impact on the press casing failure.
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ABSTRACT
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The influence of yttrium on the corrosion resistance of four valve steels (X33CrNiMn23-8, X50CrMnNiNbN21-9, X53CrMnNiN20-8 and X55CrMnNiN20-8) in combustion gases of fuel oil containing 10 wt. % of biocomponents has been studied at 1173 K... more
The influence of yttrium on the corrosion resistance of four valve steels (X33CrNiMn23-8, X50CrMnNiNbN21-9, X53CrMnNiN20-8 and X55CrMnNiN20-8) in combustion gases of fuel oil containing 10 wt. % of biocomponents has been studied at 1173 K under thermal shock conditions. These experiments have been carried out by rapid heating of the studied materials up to 1173 K and after two hours cooling down to room temperature. These thermal shocks have been repeated hundreds of times, determining after every shock the mass changes of the corroded samples. It has been found that small amount of yttrium deposited on the steel surface using electrochemical treatment considerably improves the scale adherence and consequently corrosion resistance in the case of X33CrNiMn23-8 steel, containing the highest chromium concentration.
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The corrosion behavior of four valve steels (X33CrNiMn23-8, X50CrMnNiNbN21-9, X53CrMnNiN20-8 and X55CrMnNiN20-8) in combustion gases of fuel oil, containing different bio-component concentrations of (5 and 10 wt. %) has been studied under... more
The corrosion behavior of four valve steels (X33CrNiMn23-8, X50CrMnNiNbN21-9, X53CrMnNiN20-8 and X55CrMnNiN20-8) in combustion gases of fuel oil, containing different bio-component concentrations of (5 and 10 wt. %) has been studied under thermal shock conditions. It has been found that the addition of bio-components to the fuel oil decreases the corrosion resistance of all steels under investigation, this effect being the stronger, the higher was the concentration of bio-component addition. It has been shown, that in spite of bio-component addition, the X33CrNiMn23-8 steel containing the highest chromium concentration, behaved much better than three remaining steels due to the formation of the highly protective chromia scale.
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In this work it will be presented the results of calculation of energy activation Q of selected industrial steels (e.g. grade 55 - carbon steel, LH15 – bearing steel, H10S2M, 4H14N14W2M and 50H21G9N4 valve steels) according to Polish Norm... more
In this work it will be presented the results of calculation of energy activation Q of selected industrial steels (e.g. grade 55 - carbon steel, LH15 – bearing steel, H10S2M, 4H14N14W2M and 50H21G9N4 valve steels) according to Polish Norm by two methods. In the first method the calculations of Q are based on the dependence of value of parabolic growth rate constants kp in function of reciprocal temperature. The second method is based on the calculated parameters, which allow to determine the value of Q for examined steels by using value of Q for pure iron, taken from literature data, and the particular values of mass concentrations of elements in oxidised steels. The growth kinetics of layers were almost according to parabolic law. The values of parabolic rate constant kp were calculated on the basis of measurements of thickness of oxide layers. To the experiment the cylindrical specimens were used. The isothermal process of oxidation was conducted in chamber furnace at 1100, 1060, ...
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In this work a failed rotor shaft of φ 7.2 mm diameter manufactured from constructional steel 44SMn28 (1.0762) was examined. Fracture splitting into 2 pieces in the threaded part of the shaft in a direction parallel to the longitudinal... more
In this work a failed rotor shaft of φ 7.2 mm diameter manufactured from constructional steel 44SMn28 (1.0762) was examined. Fracture splitting into 2 pieces in the threaded part of the shaft in a direction parallel to the longitudinal axis occurred. The failure was induced by mechanical forces in the threading process. The failed shaft was examined on a metallographic and scanning microscope. It was found that the failure was caused by excessive accumulation of MnS inclusions in an unfavourable banded formation.
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In this paper we give a presentation of the recently developed approaches concerned of the rate of oxidation the Arema steel at high-temperature in first stage of this process. The comparison analysis was performed on the basis of the... more
In this paper we give a presentation of the recently developed approaches concerned of the rate of oxidation the Arema steel at high-temperature in first stage of this process. The comparison analysis was performed on the basis of the experimental results of oxidation of cylindrical specimens made of above steel. The experiment was carried out in chamber furnace on series of specimen with dimension Φ = 20 , l=30 mm. The specimens were oxidized at 1000 °C for 10 - 2280 minutes in air and then quenched in silica sand, afterwards were measured and weighed both with and without of scale. The analysis reveals that for longer oxidation time than one hour influence of linear dependence on parabolic growth of scale can be neglected.
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The oxidation resistance of two X33CrNiMn23-8 and X50CrMnNiNbN21-9 steels, utilized for the production of valves in Diesel engines has been studied under thermal shock conditions. It has been found that X50CrMnNiNbN21-9 steel undergoes... more
The oxidation resistance of two X33CrNiMn23-8 and X50CrMnNiNbN21-9 steels, utilized for the production of valves in Diesel engines has been studied under thermal shock conditions. It has been found that X50CrMnNiNbN21-9 steel undergoes under such sever conditions dramatic degradation, due to extensive cracking and scale spallation. The second X33CrNiMn23-8 steel, with higher chromium concentration behaved much better, due to the formation of the protective chromia scale. It has been found also that both steels under investigation, covered with metalceramic hybrid coating, show excellent oxidation resistance.
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The oxidation kinetics of four Fe-Cr-Mn-Ni based steels, utilized in automobile industry, have been studied as a function of temperature (973–1273 K) and oxygen partial pressure (5–105 Pa). It has been shown that the rate of corrosion of... more
The oxidation kinetics of four Fe-Cr-Mn-Ni based steels, utilized in automobile industry, have been studied as a function of temperature (973–1273 K) and oxygen partial pressure (5–105 Pa). It has been shown that the rate of corrosion of these steels under isothermal conditions is determined by diffusion of reagents through the scale, which phase composition and morphology depend first of all on chromium and to some extend also on nickel and manganese contents. The highest oxidation resistance at high temperatures is observed in the case of the X33CrNiMn23-8 steel, containing highest chromium concentration, equal 23.4 wt.% and nickel equal 7.8 wt.%. The remaining three steels with virtually the same chromium content (≈20 wt.%), but lower than that in the first one, show comparable oxidation resistance. Small differences in the oxidation rates of these three steels may be related to different nickel and manganese contents. It has been found also that the rate of corrosion of all stee...