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EN
This work deals with the effect of austempering temperature and time on the microstructure and content of retained austenite of a selected cast steel assigned as a material used for frogs in railway crossovers. Bainitic cast steel was austempered at 400°C, 450°C and 500°C for two selected times (0.5 h, 4.0 h) to study the evolution of the microstructure and retained austenite content. The microstructure was characterized by optical microscopy, X-ray diffraction analyses (XRD), and hardness tests. Phase transformations during and after austempering were determined by dilatometric methods.The increase in isothermal temperature causes an increase in time to start of bainitic transformation from 0.25 to 1.5 s. However, another increase in temperature to 500°C shifts the incubation time to as much as 11 s. The time after which the transformations have ended at individual temperatures is similar and equal to about 300 s (6 min.). The dilatation effects are directly related to the amount of bainite formation. Based on these we can conclude that the temperature effect in the case of cast steel is inversely proportional to the amount of bainite formed. The largest effect can be distinguished in the case of the sample austempered at 400°C and the smallest at 500°C. Summarizing the dilatometric results, we can conclude that an increase in austempering temperature causes an increase in austenite stability. In other words, the chemical composition lowers (shifts to lower temperatures) the range of bainite transformation. It is possible that at higher austempering temperatures we will receive only stable austenite without any transformation. This is indicated by the hatched area in Figure 4b. This means that the heat treatment of cast steel into bainite is limited on both sides by martensitic transformation and the range of stable austenite. The paper attempts to estimate the content of retained austenite with X-ray diffraction.
EN
Materials based on cast irons are often used for protection against wear. One of the methods of creating protective surface with cast iron structures is hardfacing. The application of hardfacing with self shielded flux cored wire with high carbon content is one of the economical ways often used to protect machinery parts exposed to both abrasion and erosion. The wear resistance of hardfacings depends on their chemical composition, structure obtained after hardfacing, parameters of depositing process andspecific conditions of wear. As the base material in the investigation the steel grade S235JR was used. The wear behavior mechanism of hardfacings made with one type of self shielded flux cored wire and different process parameters were evaluated in thispaper. Structures obtained in deposition process were different in hardness, amount of carbides and resistance to wear with two investigated impingement angles. The erosion tests showed that impingement angle 30° gives lower erosion rate than angle 60°.
3
Content available remote Spawanie produkcyjne odlewu staliwnego żaroodpornego GX40NiCrNb35-45
PL
W pracy przedstawiono przykładowe wyniki badań kwalifikowania technologii spawania produkcyjnego odlewu staliwnego żaroodpornego w gatunku GX40NiCrNb35-45 przy użyciu materiału dodatkowego w gatunku WZ 35 45 Zr wg PN-EN ISO 14343. Badanie kwalifikowania technologii spawania wykonano zgodnie z PN-EN ISO 11970. Złącze próbne wykonano metodą 141 i następnie przeprowadzono badania nieniszczące oraz niszczące określające własności mechaniczne złącza. Wykonane badania pozwoliły spełnić wymagania zawarte w PN-EN ISO 11970 i były podstawą do wystawienia protokołu kwalifikowania technologii spawania.
EN
The paper presents the results of qualification of production welding procedures for heat-resistant cast steel in grade GX40NiCrNb35-45 with used filler material in grade WZ 35 45 Zr (PN-EN ISO 14343). Qualification of welding technology was made in accordance to PN-EN ISO 11970. Test welded joint was made using 141 method and non-destructive and destructive testing were performed in order to determine the mechanical properties of the welded joint. Completed tests met the requirements of PN-EN ISO 11970 and were the basis of the welding procedure qualification record.
4
Content available remote Properties of welded joints made of cast steel GX8ONil2-l
PL
Przedstawiono wyniki badań złączy spawanych ze staliwa GX8CrNi12-1. Jest to staliwo o mikromikrostrukturze martenzytycznej do stosowania w temperaturze pokojowej i podwyższonej na urządzenia ciśnieniowe. Złącza były wykonane w pozycji naściennej (PC) oraz w pozycji pionowej z dołu do góry (PF). Zastosowanie takich pozycji jest podyktowane warunkami przemysłowymi i koniecznością spawania odlewów staliwnych w wymienionych pozycjach. Spawanie w ww. pozycjach daje w pełni pewność, że próbki zostały pobrane z miejsc o najmniejszej i największej ilości wprowadzonego energii liniowej łuku. W artykule opisano proces spawania ręcznego elektrodą otuloną (111) i obróbkę cieplną po spawaniu. Złącza próbne poddano badaniom niszczącym: badanie na rozciąganie poprzeczne, udarności, twardości, makroskopowe i mikroskopowe. W otrzymanych wynikach badań zauważalne są różnice we właściwościach złączy wykonywanych w różnych pozycjach, co związane jest z ilością ciepła wprowadzonego do złącza podczas procesu spawania.
EN
The article presents test results concerning welded joints made of cast steel GX8CrNil2-l. The above-named cast steel has a martensitic microstructure and can be used in pressure equipment operated at ambient and high temperature. The test joints were made in the horizontal position and in the vertical up position. The foregoing was dictated by the fact that the above-named positions arę used in industrial conditions, e.g. when welding steel castings. The welding process performed in the above-named positions ensured that specimens were sampled from areas exposed to the lowest and highest are linear energy. The article describes the process of manual metal arc welding (111) and the post-weld heat treatment. The test joints were subjected to destructive tests including transverse tensile tests, impact strength tests, hardness measurements as well as macro and microscopic tests. The test results revealed differences in properties of joints made in different positions, resulting from various heat inputs to joints during welding.
EN
The article presents test results concerning the welding procedure qualification of the production welding of heat-resistant cast steel GX40NiCrSiNb35-25 (1.4852) performed using filler metal WZ 25 35 Zr according to PN-EN ISO 14343. The welding procedure qualification test was performed in accordance with PN-EN ISO 11970. The test joint made using the TIG method (141) was subjected to non-destructive and destructive tests enabling the identification of the mechanical properties of the joint. The test results satisfied the requirements contained in PN-EN ISO 11970 and constituted the basis enabling the preparation of a related welding procedure qualification report.
PL
Przedstawiono wyniki badań kwalifikowania technologii spawania produkcyjnego odlewu staliwnego żaroodpornego w gatunku GX40NiCrSiNb35-25 (1.4852) przy użyciu materiału dodatkowego w klasie WZ 25 35 Zr wg PN-EN ISO 14343. Badanie kwalifikowania technologii spawania wykonano zgodnie z normą PN-EN ISO 11970. Złącze próbne wykonano metodą 141 (TIG) i następnie przeprowadzono badania nieniszczące oraz niszczące określające własności mechaniczne złącza. Wyniki badań spełniły wymagania zawarte w PN-EN ISO 11970 i były podstawą do wystawienia protokołu kwalifikowania technologii spawania.
EN
This work deals with the effect of heat treatment on a microstructure and mechanical properties of a selected cast steel assigned as a material used for frogs in railway crossovers. Materials used nowadays in the railway industry for frogs e.g. Hadfield cast steel (GX120Mn13) or wrougth pearlitic steel (eg. R260) do not fulfil all exploitation requirements indicated in the UIC (International Union of Railways) Decision No. 1692/96 in terms of train speed that should be reached on railways. One of the possible solution is using a cast steel with bainitic or bainitic-martensitic microstructure that allows to gain high strength properties the ultimate tensile strength (UTS) of 1400 MPa, the tensile yield strength (TYS) of 900 MPa and the hardness of up to 400 BHN. The tested material is considered as an alternative to Hadfield cast steel that is currently used for railway frogs. Results of an experimental analysis of the effect of conducted heat treatment on a microstructure, the volume fraction of retained austenite and mechanical properties of bainitic steel, are shown in this paper. It was found that, the heat treatment leads to a stabilization of retained austenite in grain boundaries area of the primary austenite. Additionally, the heat treatment according to the variant #3 results with an almost 3-times higher impact toughness to that exhibited by material subjected to the other treatments.
7
Content available remote Analiza przyczyn pęknięć w złączu rura płuczkowa-zwornik w wiertnictwie
PL
W pracy omówiono przyczyny występowania pęknięć złączy rura-zwornik podczas eksploatacji rur płuczkowych. Na podstawie badań stwierdzono niewłaściwy sposób wykonania złącza – elektrody zostały źle dobrane i sprzyjały powstawaniu pęknięć. Ujawniono również wykorzystanie do produkcji rur płuczkowych niewłaściwego gatunku stali. Dla porównania przedstawiono zmiany właściwości i mikrostruktury złącza rura zwornik wykonanego metodą zgrzewania tarciowego.
EN
The paper presents analysis of the causes of cracks in the pipe-nipple joint region of the drill pipes occurred during service. The results of performed examinations showed the wrong way of making the pipe-nipple joint by welding instead of friction welding. In addition, electrodes used for welding were incorrect and favored crack nucleation and propagation in the heat affected zone of nipple joint. Also discloses the use of the drill pipe of the wrong steel grade. The changes in hardness and microstructure of the pipe-nipple joint properly made by friction welding were shown for comparison.
EN
This work deals with the influence of heat treatment on microstructure and tribological properties of specimen cast assigned as a material used for frogs in railway crossovers. Materials used nowadays in the railway industry for frogs: Hadfield cast steel (GX120Mn13) and forged pearlitic steel (R260) do not fulfil strict conditions of exploitation and speed that should be reached on railway as indicated in the UIC Decision No. 1692/96. One of the possible solutions is using cast steel with bainitic or bainitic-martensitic microstructure, which allows to gain high strength properties (Rm = 1400 MPa, Rp0,2 = 900 MPa and up to 400 BHN). The test material is an alternative to railway frogs made of Hadfield cast steel. It remains problematic to determine the properties at the weld of the frog with the rail, which can also have bainitic microstructure. To ensure similar wear in both the resistance joint and the base material the resistance butt joint should have almost the same mechanical and tribological properties as the base metal. The main objective of the present work is to study the influence of heat treatment on microstructure and tribological properties of resistance welds made of bainitic cast steel used for frogs in railway crossovers.
PL
Niniejsza praca dotyczy wpływu obróbki cieplnej na mikrostrukturę i własności tribologiczne odlewu próbnego przeznaczonego jako materiałna krzyżownice kolejowe. Dotychczasowe materiały stosowane w kolejnictwie na krzyżownice: staliwo Hadfielda (GX120Mn13) oraz kuta stal perlityczna (R260) nie spełniają rygorystycznych warunków eksploatacji i prędkości osiąganych na nawierzchniach kolejowych zawartych w Decyzji UIC nr 1692/96. Jednym z rozwiązań jest zastosowanie materiałów o mikrostrukturze bainitycznej lub bainityczno-martenzytycznej, co umożliwia uzyskanie wysokich własności wytrzymałościowych (Rm =1400 MPa, Rp0,2 =900 MPa, twardości do 400 HBW). Badany materiałjest alternatywą dla krzyżownic kolejowych ze staliwa Hadfielda. Problematyczne pozostaje określenie również własności w miejscu połączenia krzyżownicy z szyną, która również może mieć mikrostrukturę bainityczną. Wykonane złącze zgrzewane powinno wykazywać jak najbliższe własności (mechaniczne, tribologiczne itp.) do materiału rodzimego gdyż wówczas zapewniają one równomierne zużywanie się zarówno w obszarze złącza jak i samego materiału rodzimego. W pracy określono wpływ obróbki cieplnej na mikrostrukturę i własności tribologiczne zgrzein wykonanych ze staliwa bainitycznego stosowanego na krzyżownice do rozjazdów kolejowych.
PL
W artykule przedstawiono wyniki badań skłonności do pękania zimnego stali bainitycznej T24. Wyznaczono naprężenia krytyczne dla strefy wpływu ciepła stali T24 (7CrMoVTiB10-10), które powoduje powstanie pęknięć zimnych. Wartość naprężenia wywołującego pękanie zimne wynosi 485 MPa i jest niższa od granicy plastyczności materiału spoiny.
EN
The paper presents the results of the cold crack sensitivity of the bainitic steel T24. The critical stresses for cold cracks in 7CrMo- VTiB10-10 steel within the heat affected zone were estimated. The value of the critical stresses is 485MPa i.e. lower than the yield stress for the metal in welded joint.
10
Content available remote Korozja wżerowa złączy spawanych stali austenitycznej X6CrNiTi18-10
PL
Przedstawiono badania, które pozwoliły wyjaśnić przyczyny powstawania nieszczelności w rurociągu wody chłodzącej wykonanym ze stali austenitycznej X6CrNiTi18-10 (1.4541). Ustalono, że przyczyną powstawania nieszczelności jest korozja wżerowa, w której wżery powstają na niezgodnościach spawalniczych.
EN
The experiments which allowed to account for the causes of the developing of leakiness in the cooling water pipelines made of austenitic steel X6CrNiTi 18-10 (1.4541 ) were conducted. It was found out that pitting corrosion caused the developing of the leakiness, where corrosion pits are formed at the welding irregularities.
PL
Przedstawiono wyniki badań złączy spawanych rurociągu wody chłodzącej o średnicy 323,9x4 mm wykonanego ze stali X6CrNiTi18-10 (1.4541). Badano skład chemiczny spoiny oraz materiał rodzimy rurociągu, wykonano też badania radiograficzne i penetracyjne spoin oraz analizę zgładów metalograficznych spoin. Omówiono ujawnione podczas badań niezgodności spawalnicze oraz przedstawiono możliwe przyczyny ich powstania.
EN
Results of tests of welded joints of cooling water pipeline of 232.9x4 mm diameter, made of steel X6CrNiTi18-10 (1.4541) were presented. Chemical constitution of fusion weld and pipeline native material were tested, as well as radiographic inspections, liquid-penetrant inspections and analysis of metallographic specimens of fusion welds were performed. Welding imperfections discovered during tests were discussed and possible causes of their arising were showed.
12
Content available remote Microstructure formation and properties of abrasion resistant cast steel
EN
The so-called adamitic cast steels are characterised by a high abrasion resistance. These cast steels are of a pearlitic matrix withuniformly distributed hypereutectoid cementite precipitates. Apart from hypereutectoid cementite very often transformed ledeburite alsooccurs in the microstructure of these cast steels. Such cast steels contain chromium (app. 1 %) and nickel (app. 0.5 %) as alloy additions and sometimes their silicon content is increased. The presence of molybdenum is also permissible (app. 0.4 %). The basic problem in application of these steels for structural elements constitutes their insufficient crack resistance. An improvement of mechanical properties by changes of morphology of hypereutectoid cementite and transformed ledeburite precipitates by means of the heat treatment applicationwas the aim of this study. G200CrNiMo4-3-3 cast steel was the investigated material. Changes in the morphology of hypereutectoid cementite and transformed ledeburite obtained due to the heat treatment are described in detail in the present paper. An influence of the microstructure changes on impact toughness of the investigated cast steel is presented. Investigations performed within this study will serve for the microstructure optimisation on account of functional qualities of this cast steel.
EN
This work deals with influence of heat treatment on microstructure and properties of sample cast assigned as a material used for frogs in railway crossover. Materials used in railway industry for frogs (manganese cast steel and forged pearlitic steel) do not fulfil strict conditions of exploitation of railway. One of the solutions is using cast steel with bainitic or bainite-martensite microstructure, what allows to gain high resistance properties (Rm = 1400 MPa, Rp0,2 = 900 MPa, hardness to 400 HBW). The cooling rates of rail type UIC60 shows that it is possible to reach the bainitic microstructure in cast of frog. The microstructure of lower banite should have an advantageous influence on cracking resistance. In order to set the parameters of heat treatment, the critical temperatures were determined by dilatometric methods determined. This heat treatment consisted of normalizing that prepared it to the farther process of resistance welding. Moreover, the CCT diagram of proposed bainitic cast steel was prepared. The exams were done that can be used to evaluate the influence of heat treatment on microstructure and properties of the sample cast.
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