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1
Content available remote Base pressure behaviour in a suddenly expanded duct at supersonic Mach number regimes using Taguchi design of experiments
Quadros J. D., Khan S. A., Antony A. J.
Mechanics and Mechanical Engineering
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2018
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Vol. 22, nr 4
1077--1097
EN
Experimental investigations are carried out to study the control of base pressure without and with the use of micro-jets through suddenly expanded axi-symmetric passage in the supersonic regime. Four micro jets having an orifice diameter of 1mm were located at 90˚ intervals. In the base area, active controls jets have been placed on a pitch of a circle diameter that is 1.3 times the exit diameter of the nozzle. The jets were dispensed abruptly into the axi-symmetric tube maintained at a cross-sectional area of 4.84 times the exit nozzle area. The variation of base pressure as a function of flow control parameters namely Mach number, nozzle pressure ratio (NPR) and length to diameter) ratio (L=D) are evaluated experimentally. This study also assesses the impact of flow control variables on base pressure for two cases viz. with control and without control respectively. An L9 orthogonal array of Taguchi and the analysis of variance were employed to investigate the percentage of contribution of these parameters and their interactions affecting the base pressure. The correlations between the various factors affecting the base pressure were obtained by using multiple linear regression equations. Confirmation tests were conducted in order to test the developed linear regression equations for their practical significance. Both the regression models were found to be significant and reliable with a percentage deviation lying in the range of -6:12% to 10.26% for base pressure without control and -13:92% to 6.58% for base pressure with control. Analysis of variance was also performed in order to determine the statistical significance of each parameter on the total variability of base pressure. The study concluded that Mach number is the most in fluential parameter affecting base pressure followed by NPR and L=D.
2
Content available Mathemathical Equations of the Influence of Molybdenum and Nitrogen in Welds
Węgrzyn T., Kamińska J., Piwnik J., Stanik Z.
Archives of Metallurgy and Materials
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2018
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Vol. 63, iss. 1
83--86
EN
The paper offers mathematical equations of the influence of micro-jet cooling on structure and impact toughness properties of metal weld deposit. Weld metal deposit (WMD) was carried out for standard MIG welding and for MIG welding with micro-jet cooling. This new method is very promising mainly due to the high amount of AF (acicular ferrite) and low amount of MAC (selftempered martensite, retained austenite, carbide) phases in WMD. That structure corresponds with very good mechanical properties ie. good impact toughness of welds at low temperature. Micro-jet cooling after welding can find serious application in automotive industry very soon. Until that moment only argon, helium, nitrogen and gas mixtures of argon were tested for micro-jet cooling after welding. The best results of mechanical properties of WMD in presented welding method correspond with micro-jet argon cooling.
3
Gas mixtures based on Ar-He for micro-jet cooling after MAG welding
Szczucka-Lasota B., Gajdzik B., Krzysztoforski M., Węgrzyn T., Hadryś D., Wszołek Ł.
Hutnik, Wiadomości Hutnicze
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2017
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Vol. 84, nr 7
262--265
EN
The material selected for this investigation was low alloy weld metal deposit after MAG welding with micro-jet cooling. The present investigation was aimed as the following tasks: obtained WMD with various amount of acicular ferrite in WMD in terms of helium percentage in micro-jet gas mixture. Paper focuses on low alloy steel weld properties after innovate welding method with micro-jet cooling. Weld metal deposit (WMD) for micrograph analyses and impact toughness was carried out for MAG. Until that moment only argon, helium and nitrogen were seriously tested as micro-jet gases. In that paper various gas mixtures (Ar-He) were tested for micro-jet cooling after welding. The influence of oxygen and nitrogen included in gas mixtures based on Ar-He couple on properties of WMD was also tested.
PL
Materiałem wybranym do tego badania było stopiwo uzyskane po spawaniu niestopowej stali procesem MAG z chłodzeniem mikro-jetowym. Badanie miało na celu: otrzymanie stopiwa z różną ilością drobnoziarnistego ferrytu (acicular ferrite) w zależności od zawartości helu w mieszance z argonem stosowanej do schładzania mikro-jetowego. W artykule skoncentrowano się na właściwościach złącza ze stali niestopowej po wprowadzeniu innowacyjnej metody spawania z wykorzystaniem chłodzenia mikro-jetowego. Stopiwo do badań mikrostruktury i udarności było uzyskane po spawaniu procesem MAG. Do tej pory do schładzania mikro-jetowego były dokładnie testowane tylko takie gazy jak argon, hel i azot. W tym artykule badano różne mieszanki gazowe (Ar-He) jako gazy mikro-jetowe. Na własności stopiwa badano również dodatkowy wpływ tlenu i azotu zawartego w mieszankach gazowych opartych na Ar-He.
4
Content available Low Alloy Steel Structures After Welding with Micro-Jet Cooling
Węgrzyn T., Piwnik J., Hadryś D., Wszołek Ł.
Archives of Metallurgy and Materials
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2017
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Vol. 62, iss. 1
115--118
EN
The paper focuses on low alloy steel after innovate welding method with micro-jet cooling. Weld metal deposit (WMD) was carried out for welding and for MIG and MAG welding with micro-jet cooling. This method is very promising mainly due to the high amount of AF (acicular ferrite) and low amount of MAC (self-tempered martensite, retained austenite, carbide) phases in WMD. That structure corresponds with very good mechanical properties, ie. high impact toughness of welds at low temperature. Micro-jet cooling after welding can find serious application in automotive industry very soon. Until that moment only argon, helium and nitrogen were tested as micro-jet gases. In that paper first time various gas mixtures (gas mixtures Ar-CO2) were tested for micro-jet cooling after welding.
5
Content available Impact Toughness of Steel WMD after TIG Welding
Węgrzyn T., Piwnik J., Stanik Z., Węgrzyn D., Sieteski D.
Archives of Metallurgy and Materials
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2017
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Vol. 62, iss. 3
1647--1650
EN
The material selected for this investigation was low alloy weld metal deposit after TIG welding with various amount of oxygen in weld metal deposit (WMD). After TIG process it is difficult to get proper amount of oxygen in WMD on the level much lower than 350 ppm. The highest impact toughness of low alloy WMD corresponds with the amount of oxygen in WMD above 350 ppm. In the paper focuses on low alloy steel after innovate welding method with micro-jet cooling that could be treated as a chance on rising amount of oxygen in weld. Weld metal deposit (WMD) was carried out for TIG welding with micro-jet cooling with various amount of oxygen in WMD. In that paper various gas mixtures (gas mixtures Ar-O2 and Ar-CO2) were tested for micro-jet cooling after TIG welding. An important role in the interpretation of the results can give methods of artificial intelligence.
6
Content available The impact of gas on the tribological properties of steel 16MnCr5 after surfacing with micro-jet cooling
Tarasiuk W., Piwnik J., Hornik A., Węgrzyn T., Majewski W.
Journal of KONES
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2016
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Vol. 23, No. 4
541--548
EN
This paper presents results of experimental research concerning the impact of an innovative method of micro-jet cooling on the padding weld performed with MAG welding. It enables to steer the parameters of weld cooling in a precise manner. Micro-jet cooling is a novel method patented in 2011. In addition, various elements, which may e.g. enhance hardness or alter tribological properties, can be entered into its top surface, depending on the applied cooling gas. The micro-jet welding method is the innovative method, which reduces the intensity of abrasive wear. The method can be used as a basic finishing or a regeneration method. An innovative technology for micro-jet is used to cool the weld surface that is, using a micro-welding jet cooling. This allows accurate and complete control of the surface structure of the deposit. The material under study was steel 16MnCr5, which was subject to the welding process with different gases of micro-jet cooling. Nitrogen and air was used as a cooling gas. The main parameter of weld assessment was wear intensity. The tests were conducted in a tribological pin-on-disc type position. T-11 pin-on-disc tester allows for indicating basic wear parameters (wear intensity, wear coefficient, wear force). Based on results of experiment the application of nitrogen in micro-jet cooling of the padding weld in the welding process of steel 16MnCr5 beneficially affects resistance to abrasive wear.
7
Content available The use of compressed air for micro-jet cooling after MIG welding
Hadryś D., Węgrzyn T., Piwnik J., Stanik Z., Tarasiuk W.
Archives of Metallurgy and Materials
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2016
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Vol. 61, iss. 3
1405--1408
EN
The material selected for this investigation was low alloy steel weld metal deposit (WMD) after MIG welding with micro-jet cooling. The present investigation w*as aimed as the following tasks: obtained WMD with various amount of acicular ferrite and further analyze impact toughness of WMD in terms of acicular ferrite amount in it. Weld metal deposit (WMD) was first time carried out for MIG welding with micro-jet cooling of compressed air and gas mixture of argon and air. Until that moment only argon, helium and nitrogen were tested as micro-jet gases for MIG/MAG processes. An important role in the interpretation of the results can give methods of artificial intelligence.
8
Content available Wear Resistance of Steel 20MnCr5 After Surfacing with Micro-jet Cooling
Tarasiuk W., Piwnik J., Węgrzyn T., Sieteski D.
Archives of Foundry Engineering
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2016
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Vol. 16, iss. 3
121--124
EN
This paper presents results of experimental research concerning the impact of an innovative method of micro-jet cooling on the padding weld performed with MIG welding. Micro-jet cooling is a novel method patented in 2011. It enables to steer the parameters of weld cooling in a precise manner. In addition, various elements which may e.g. enhance hardness or alter tribological properties can be entered into its top surface, depending on the applied cooling gas. The material under study was steel 20MnCr5, which was subject to the welding process with micro-jet cooling and without cooling. Nitrogen was used as a cooling gas. The main parameter of weld assessment was wear intensity. The tests were conducted in a tribological pin-on-disc type position. The following results exhibit growth at approximately 5% in wear resistance of padding welds with micro-jet cooling.
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