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1

Plastic Properties of Fine-Grained WMD After Micro-Jet Cooling

Hadryś D., Węgrzyn T., Piwnik J.

Archives of Metallurgy and Materials

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2014

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Vol. 59, iss. 3

919--923

EN

Micro-jet welding is an innovative method of weld forced cooling immediately after welding. It allows to obtain weld with superior properties in comparison to conventional welding. The reason for this is to obtain a more favorable structure of the weld metal deposit (WMD) with much higher amount of acicular ferrite (AF). Different structures and mechanical properties of weld metal deposit were obtained by using various gases for cooling. The paper shows the relationship between the type of gas for micro-jet cooling and plastic properties of the weld joint. Coefficient of restitution and plastic strain were selected to describe changes of weld plastic properties for different micro-jet cooling gases. The tests were performed in dynamic conditions (impact).

PL

Spawanie z chłodzeniem mikrojetowym to nowatorska metoda spawania z wymuszonym chłodzeniem spoiny bezpośrednio po spawaniu. Pozwala ona na uzyskanie połączeń spawanych o właściwościach lepszych w porównaniu do spawania tradycyjnego. Przyczyną tego jest uzyskiwania korzystniejszej struktury stopiwa z większą zawartością drobnoziarnistego ferrytu (acicular ferrite – AF). Dzięki zastosowaniu różnych gazów do chłodzenia spoiny, można uzyskiwać różne struktury stopiwa i właściwości mechaniczne. W artykule przedstawiono zależność pomiędzy rodzajem gazu do chłodzenia mikrojetowego, a własnościami plastycznymi połączenia spawanego. Jako wielkości opisujące własności plastyczne wybrano współczynnik restytucji i odkształcenie trwałe. Testy przeprowadzono w warunkach dynamicznych.

2

Acicular Ferrite in Micro Welding Technologies

Węgrzyn T., Piwnik J., Hadryś D.

Archives of Metallurgy and Materials

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2014

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Vol. 59, iss. 2

581--583

EN

Laser is widely applied in micro welding. Apart from that method, welding with micro-jet cooling could be treated as another important method for thin structure welding. Until that moment micro-jet technology is not very popular. An article presents actual information about innovate welding technology with micro-jet cooling in comparison with standard laser welding. There were given information about influence of both micro welding method on metallographic structure of thin steel welds. Amount of AF was tested in two cases.

PL

Laser jest szeroko stosowany w mikro-spawaniu. Oprócz tej metody, spawanie z chłodzeniem mikrojetowym powinno być traktowane jako ważna metoda spawania cienkościennych konstrukcji. W artykule przedstawiono innowacyjną technologię spawania z chłodzeniem mikrojetowym w porównaniu do spawania laserowego. Uzyskano informacje o wpływie obu metod na strukturę metalograficzną stalowych cienkościennych konstrukcji. Zawartość ferrytu AF była porównana w obu przypadkach.

3

Heat treatment of Ni–Mn–Cu cast iron

Janus A., Granat K.

Archives of Civil and Mechanical Engineering

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2014

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Vol. 14, no. 4

602--607

EN

Examined was the influence of chemical composition defined by the nickel equivalent, as well as time and temperature of soaking on course of decomposition process of metallic matrix in the austenitic Ni–Mn–Cu cast iron. In alloys with the equivalent value ranging from 16.0% to 23.0%, with properly selected heat-treatment parameters, possible is controlled, partial transition of austenite to hard acicular ferrite. Obtained is the structure morphologically corresponding to that of ausferrite, characteristic for cast iron quench-hardened with isothermal transformation (e.g. CGI or ADI). Replacing the quench-hardening operation by soaking permits, among others, obtaining homogeneous structure in the entire cross-section of solid thick-walled castings or elimination of quenching stresses.

4

Plastic properties of weld after micro-jet cooling

Piwnik J., Hadryś D., Skorulski G.

Journal of Achievements in Materials and Manufacturing Engineering

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2013

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Vol. 59, nr 1

20--25

EN

Purpose: of that paper was analysing main plastic properties of welds made by MIG method with micro-jet cooling. The main reason of it was investigate possibilities of getting better plastic properties of welds made by MIG method with micro-jet cooling than welds made by ordinary welding method. It is possible because higher amount of acicular ferrite (AF) in WMD (weld metal deposit) is obtained in MIG method with micro-jet cooling in relation to ordinary welding method. Design/methodology/approach: During research Erichsen cupping tests and bending tests were carried out for welds made by MIG method with micro-jet cooling and ordinary welding method. Findings: High amount of acicular ferrite influences positively on plastic properties. Higher value of plastic parameters were observed for welds made by MIG method with micro-jet cooling. Research limitations/implications: That research was made for MIG method only. Another method of welding was not tested. Other methods of welding have not been tested, but it is suspected that similar phenomena are taking place. Practical implications: MIG method with micro-jet cooling `it is way to get better plastic properties of welds in relation to welds made by ordinary welding method. It is very important because it could be used to steering of mechanical properties of welded constructions. Originality/value: In this research welds made by new method of welding (welding with micro-jet cooling) were compare witch welds made by ordinary welding method. New method of welding is very promising and capable of industrial application, mainly due to the significant improvement of weld properties and quality.

5

Oxygen in steel WMD after welding with micro-jet cooling

Węgrzyn T., Piwnik J., Hadryś D.

Archives of Metallurgy and Materials

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2013

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Vol. 58, iss. 4

1067--1070

EN

Until that moment micro-jet technology was tested only for MIG welding process with argon as a shielded gas. An article presents actual information about innovate welding technology with micro-jet cooling. There are put down information about gases that could be chosen both for MIG/MAG welding and for micro-jet process. There were given information about influence of various micro-jet gases on metallographic structure of steel welds. Mechanical properties of weld was presented in terms of oxygen amount in WMD (weld metal deposit).

PL

Dotychczas technologia mikrojetowa była stosowana tylko w spawalniczym procesie MIG, gdzie gazem osłonowym był argon. W artykule przedstawiono innowacyjną technologię spawania z chłodzeniem mikrojetowym. Podano informacje zarówno dla gazów, które mogą być wybrane dla spawania MIG/MAG i dla mikrojetowego procesu. Uzyskano informacje o wpływie doboru gazu mikrojetowego na strukturę metalograficzną stalowych spoin. Własności mechaniczne złącza podano w funkcji zawartości tlenu w stopiwie.

6

Parameters of welding with micro-jet cooling

Węgrzyn T., Piwnik J., Łazarz B., Wieszała R., Hadryś D.

Archives of Materials Science and Engineering

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2012

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Vol. 54, nr 2

86-92

EN

Purpose: of that paper was analysing main welding process with parameters of micro-jet cooling. The main reason of it was investigate possibilities of getting varied amount of acicular ferrite (AF) in WMD (weld metal deposit). High amount of acicular ferrite influences positively impact toughness of weld. For optimal amount of AF it is necessary to determine the parameters (eg. number of clusters, diameter of stream) of the micro-jet. Design/methodology/approach: During research with varied micro-jet parameters the chemical analysis, micrograph tests and Charpy V impact test of the metal weld deposit on pendulum machine were carried out. The Charpy V impact test was prepared according to standard ISO EN 148-1 Metallic materials - Charpy pendulum impact test - Part 1: Test method. Samples for impact testing were prepared according to standard ASTM A370. Findings: Varied amount of acicular ferrite in weld metal deposit (in range 55-75%) in terms of micro-jet cooling parameters (numbers of jet, gas pressure). This high amount of acicular ferrite is unheard in weld metal deposit in another way or other methods of welding like MAG or TIG. Research limitations/implications: That research was made for MIG method (according to PN-EN ISO 4063:2009) only. Another method of welding in this article was not tested. Other methods (for eg. MAG, TIG) have not been tested, but it is suspected that similar phenomena are taking place. Practical implications: Micro-jet cooling it is way to get higher amount of acicular ferrite in weld metal deposit than the usual methods of welding. It is very important because it could be used to steering of weld joint structure and mechanical properties (for example impact toughness). Originality/value: In this research new method of cooling weld joint during welding was used. At the present time use of micro-jet cooling while MIG is in the testing phase and requires an accurate diagnosis.This method is very promising and capable of industrial application, mainly due to the significant improvement of weld quality and reduces costs.

7

Micro-jet cooling gases for low alloy steel welding

Węgrzyn T., Piwnik J., Łazarz B., Plata M.

Archives of Materials Science and Engineering

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2012

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Vol. 58, nr 1

40--44

EN

Purpose: of that paper was analysing main gases used in micro-jet cooling after welding. The main reason of it was to investigate possibilities of getting varied amount of acicular ferrite (AF) in WMD (weld metal deposit). High amount of acicular ferrite influences positively impact toughness of weld. Design/methodology/approach: During research varied gases were testes as micro-jet parameters. Further the chemical analysis, micrograph tests and Charpy V impact test of the metal weld deposit on pendulum machine were carried out. The Charpy V impact test was prepared according to standard ISO EN 148-1 Metallic materials - Charpy pendulum impact test - Part 1: Test method. Samples for impact testing were prepared according to standard ASTM A370. Findings: Varied amount of acicular ferrite in weld metal deposit (in range 55%-75%) in terms of micro-jet cooling parameters (in that case kind of gas and gas pressure). This high amount of acicular ferrite is unheard in weld metal deposit in another way or other methods of welding such as MAG or TIG. Research limitations/implications: That research was made for MIG method (according to PN-EN ISO 4063:2009) only. Another method of welding in this article was not tested. Practical implications: Micro-jet cooling it is way to get higher amount of acicular ferrite in weld metal deposit than the usual methods of welding. It is very important because it could be used to steering of weld joint structure and mechanical properties (for example impact toughness). Originality/value: In this research new method of cooling weld joint during welding was used. At the present time use of micro-jet cooling while MIG is in the testing phase and requires an accurate diagnosis. This method is very promising and capable of industrial application, mainly due to the significant improvement of weld quality and reduces costs.

8

Properties of high manganese Fe-Mn-Al-C alloys

Mazancova E., Rucka Z., Mazanec K.

Archives of Materials Science

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2007

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Vol. 28, nr 1-4

95-99

EN

Acicular ferrite (AF) microstructure represents an excellent contribution of mechanical properties and the toughness level detected in low-alloy steel. Majority of neighbouring plates (laths) have mutual high-angle misorientation in contradistinction to upper bainite (B) microstructure. High-angle interfaces are only formed between B-packets consisting of low-angle plates (laths) set. The cleavage unit crack path (UCP) has been found to be a distance between two grains of high-angle ferrite regions (corresponding to the two crystallographic B-packets boundaries). In the AF the UCP value is defined as a distance between two neighbouring highly misorientated plates. It shows the UCP values are shorter what results in higher deviation frequency and consequently in limited (retarded) cleavage crack propagation. The nucleation AF conditions in austenite matrix after application of an optimized thermomechanically controlled process consisting of the consecutive straining processes realized in recrystallization and in non recrystallization regions have been determined. The applied nucleation mechanism (base on the nucleation process realized in structural matrix) represents the second variant resulting in the AF formation. The beneficial resistance of the AF particles to hydrogen embrittlement can be held for a very important property of this microstructure what demonstrates the valuable contribution of this microstructure to its engineering application. The AF microstructure is associated with effective combination of strength and toughness. The behaviour of this microstructure is compared with upper bainite properties. Following differences between the microstructural parameters are detected. The AF is nucleated on intragranular inclusions. In majority, plates show high-angle arrangement in comparison with upper bainite. Numerous low-angle interfaces are detected within crystallographic upper bainite packets. In AF microstructure the unit crack path is defined as a distance between two neighbouring highly misorientated plates. The AF microstructure contributes to the achievement of high steels resistance to hydrogen induced cracking due to special arrangement of its plates.

9

Contribution to the Modelling of Processes Controlling the Acicular Ferrite (AF) Formation in C-Mn Steels

Mazancová E., Jonšta Z., Mazanec K.

Machine Dynamics Problems

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2006

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Vol. 30, No. 4

60-67

EN

Due to special morphology, AF microstructure makes possible to obtain a very favourable combination of mechanical properties (strength, ductility and toughness). The significant parameter is the deflection mechanism limiting cleavage crack propagation. Although the nucleation role of fine special non-metallic inclusions as inoculants controlling the austenite (A)-decomposition into ferrite has been described in great number of works, the comprehensive mechanism of these processes has not been developed. Due to large variety of non-metallic particles acting as inoculants in above considered transformation process, this solution is not facile. The nucleation potency of individual phases comprising complex inclusions has not been assessed so far. In the present contribution the investigation will be devoted to the finding of model being able to describe the nucleating behaviour of some complex inclusions based on manganese - silicate (MnO-SiO2) and on the nucleating effect of Mg-addition (MgO) to the basic chemical constitution resulting from deoxidization with Mn/Si/Ti. Among considered mechanism as the most perspective one could be held the formation of Mn-depleted zone being the nucleation site for intragranular A-decomposition into ferrite phase. It has been proposed this zone is formed around inclusion by the subsequent MnS nucleation on it. This process is accompanied with the subsequent Mn-diffusion running in the steel matrix to the MnS-nuclei. The following conclusions can be determined from the achieved results in investigated steel types. The nucleation potency of some inclusions complex represents a decisive initiation parameter in decomposition of A into AF. It has been established the higher density number of dispersed fine intragranular particles (0.5-2.0 µm) is very effective in the refinement of ferrite plates by AF nucleation. The non-metallic inclusions type participating in the considered nucleation process is determined by steel deoxidization. Precipitation of MnS on primary inclusions (investigated influence of Mn/Si and Mn/Si/Ti) has been analyzed. For both examples the same physical metallurgical characteristics leading to the formation of Mn-depleted zone and simultaneously realized MnS nucleation on applied non-metallic inclusions have been found. In case of AF nucleation on inclusions after Mg addition the mechanism of Mn-depleted zone has been also confirmed. The mechanism of AF formation in connection with Mn-depleted zone existence around the primary steel inclusions accompanied with MnS formation has been analyzed in detail. This complex mechanism can be considered as a very attractive model making possible to predict the AF nucleability in austenitic matrix.

10

Kształtowanie składu chemicznego wydzieleń tlenkowo - siarczkowych przy odtlenianiu stali manganem, krzemem i tytanem

Wypartowicz J., Podorska D.

Hutnik, Wiadomości Hutnicze

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2006

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Vol. 73, nr 3

91-96

PL

Przeanalizowano warunki, w jakich w niskowęglowej stali niskostopowej, zawierającej wydzielenia tlenkowe MnO-SiO2-TiO2 tworzy się ferryt iglasty, korzystny dla własności wytrzymałościowych. Stwierdzono, że decydującą rolę odgrywa skład chemiczny i temperatura likwidus fazy tlenkowej. Za pomocą własnego programu komputerowego obliczono ewolucję temperaturową stanów równowagi termodynamicznej między ciekłą stalą, zawierającą Fe, Mn, Si, Ti, O a ciekłą fazą tlenkową. Wyniki obliczeń wskazują, że program i zastosowana procedura obliczeniowa mogą służyć do projektowania procesu przygotowania stali o żądanym składzie chemicznym i ilości wydzieleń tlenkowych.

EN

The conditions relevant for acicular ferrite formation in low carbon low alloyed steel containing MnO-SiO2-TiO2 precipitates were analyzed. Acicular ferrite is beneficial for steel strength. It was concluded that the composition and liquidus temperature of oxide solution play a dominant role. The temperature evolution of thermodynamic equilibrium states between liquid steel containing Fe, Mn, Si, Ti, O and liquid oxide phase was determined by means of authors computer program. The results of calculations reveal, that the program and applied calculation procedure may by utilized in designinh the process of preparation of steel of required amount and chemical composition of oxide inclusions.

11

Calculations of oxide inclusions composition in the steel deoxidized with Mn, Si and Ti

Podorska D., Drożdż P., Falkus J., Wypartowicz J.

Archives of Metallurgy and Materials

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2006

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Vol. 51, iss. 4

581-586

EN

The work deals with the determination of the composition of liquid oxide solution MnO-SiO2-TiO2-Al2O3, present as an inclusion in liquid steel during its solidification. The region of compositions at which oxide solution remains entirely liquid at the temperatures 1523 K and 1673 was calculated by means of FACT program. The evolution of oxide phase chemical composition in thermodynamic equilibrium with liquid steel during its equilibrium solidification was calculated. The procedure of calculations may be applied in the determination of the conditions for acicular ferrite formation, which nucleates at oxide inclusions.

PL

Praca zajmuje się określeniem zmian składu ciekłego roztworu tlenkowego MnO-SiO2-TiO2-Al2O3 znajdującego się w postaci wtracenia w ciekłej stali w trakcie jej krzepnięcia. Obliczono przy pomocy programu FACT zakres składów roztworu tlenkowego, przy jakim pozostaje on całkowicie ciekły przy temperaturach 1523 i 1673 K. Wyznaczono ewolucje składu chemicznego fazy tlenkowej pozostającej w równowadze termodynamicznej z ciekłą stalą w trakcie jej równowagowego krzepnięcia. Procedura obliczeniowa może być zastosowana do określania warunków tworzenia ferrytu iglastego zarodkującego na wydzieleniach tlenkowych.