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1
Content available Oxide Layer Evolution of Cast Fe24Cr12NiXNb Heat-Resistant Cast Steels at 900°C in Atmospheric Air
Ramos P. A., Coelho R. S., Pinto H. C., Soldera F., Mücklich F., Brito P. P.
Archives of Foundry Engineering
|
2021
|
Vol. 21, iss. 1
125--131
EN
The austenitic stainless steels are a group of alloys normally used under high mechanical and thermal requests, in which high temperature oxidation is normally present due to oxygen presence. This study examines the oxide layer evolution for Fe24Cr12NiXNb modified austenitic stainless steel A297 HH with 0,09%Nb and 0,77%Nb content at 900°C under atmospheric air and isothermal oxidation. The modifiers elements such as Mo, Co and Ti, added to provide high mechanical strength, varied due to the casting procedure, however main elements such as Cr, Ni, Mn and Si were kept at balanced levels to avoid microstructure changing. The oxide layer analysis was performed by confocal laser scanning microscopy (CLS) and scanning electron microscopy (SEM). The elemental analysis of the different phases was measured with energy dispersive X-ray spectroscopy (EDX). The Nb-alloyed steel generated a thicker Cr oxide layer. Generally elemental Nb did not provide any noticeable difference in oxide scale growth, for the specific range of Nb amount and temperature studied. High temperature oxidation up to 120h was characterized by protective Cr oxidation, after this period a non-protective Fe-based oxidation took place. Cr, Fe and Ni oxides were observed in the multilayer oxide scale.
2
Content available Numerical Modelling of Micro-Stresses in Carbonised Austenitic Cast Steel Under Rapid Cooling Conditions
Tuleja J., Zatorski Z.
Archives of Metallurgy and Materials
|
2017
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Vol. 62, iss. 2A
635--641
EN
The paper presents a method of the numerical modelling of micro-stresses in carbonised austenitic cast steel being developed during rapid cooling due to differences in the values of thermal expansion coefficients for this material phases – carbides and austenitic matrix. Micro-stresses are indicated as the main cause of crack initiation in the tooling elements of carburising furnaces being mainly made of austenitic cast steel. A calculation model of carbonised and thermally fatigued austenitic cast steel was developed based on the microstructure images obtained using light microscopy techniques and the phase composition evaluated with the X-ray diffraction method. The values of the stress tensor components and the reduced stress in the complex models of test material structure were determined numerically by the finite element method. The effort analysis was performed and the areas where development of cracks is to be expected were identified, which was experimentally confirmed.
3
Content available Effect of Heat Treatment on the Microstructures 20%Cr-21%Ni-5%Si Cast Steel
Kalandyk B., Kasińska J., Olejnik E.
Archives of Foundry Engineering
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2015
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Vol. 15, iss. 2 spec.
39--42
EN
The study describes the effect of heat treatment on the microstructure of cast high-alloyed 20%Cr-21%Ni-5%Si steel. It has been found that the microstructure of the tested material in the initial state consists of an austenitic matrix and precipitates rich in Si, Cr, Ni and Mn, characterized by different morphology and distributed mainly along the grain boundaries. The conducted heat treatment (after solutioning at: 1060, 1100 and 1200ºC) has changed both morphology and chemical composition of the precipitates. Significant reduction in the Si and Ni content and slight increase in the Cr content, especially after solutioning at 1200°C, combined with a simultaneous decrease in the hardness of the precipitates was evidenced.
4
Microstructure and microhardness of annealed austenitic cast steel
Christodoulou P., Chylińska R., Garbiak M., Piekarski B.
Inżynieria Materiałowa
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2013
|
Vol. 34, nr 3
145--148
EN
The study proposes how to use the random HV0.01 microhardness measurements in the description of changes in the microstructure of 0,3C-18Cr-30Ni cast steel with an addition of titanium. The cast steel was investigated in four technological states, i.e. after annealing at 800°C for 10, 100, 500 and 1000 hours. Microhardness measurements were performed on unetched metallographic sections applying a 10 G load for 10 seconds. The measurements were taken at random, each time imposing a grid with 200 points on the surface of a metallographic section. Microhardness distribution density functions were detennined for the investigated technological cast steel States. To peaks occurring in different microhardness distribution density functions were assigned areas of the microstructure characterised by different content of the structural components.
PL
W pracy zaproponowano sposób wykorzystania losowego pomiaru mikrotwardości HV0,01 do opisu zmian w mikrostrukturze staliwa 0,3 C-18Cr-30Ni z dodatkiem tytanu. Badano staliwo w czterech stanach technologicznych - po wyżarzaniu w temperaturze 800°C przez 10, 100, 500 i 1000 godzin. Pomiary mikrotwardości przeprowadzono na zgładach nietrawionych, stosując obciążenie 10 G przez 10 sekund. Pomiary wykonano losowo, każdorazowo nakładając na powierzchnię zgładu siatkę 200 punktów. Wyznaczono funkcje gęstości rozkładów mikrotwardości dla badanych stanów technologicznych staliwa. Pikom występującym w poszczególnych funkcjach gęstości rozkładów mikrotwardości przyporządkowano obszary mikrostruktury charakteryzujące się odmiennym udziałem składników strukturalnych.
5
Content available Wearing quality of austenitic, duplex cast steel, gray and spheroidal graphite iron
Pietrowski S.
Archives of Foundry Engineering
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2012
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Vol. 12, iss. 2
235-244
EN
The current work presents the research results of abrasion wear and adhesive wear at rubbing and liquid friction of new austenitic, austenitic-ferritic ('duplex') cast steel and gray cast iron EN-GJL-250, spheroidal graphite iron EN-GJS-600-3, pearlitic with ledeburitic carbides and spheroidal graphite iron with ledeburitic carbides with a microstructure of the metal matrix: pearlitic, upper bainite, mixture of upper and lower bainite, martensitic with austenite, pearlitic-martensitic-bainitic-ausferritic obtained in the raw state. The wearing quality test was carried out on a specially designed and made bench. Resistance to abrasion wear was tested using sand paper P40. Resistance to adhesive wear was tested in interaction with steel C55 normalized, hardened and sulfonitrided. The liquid friction was obtained using CASTROL oil. It was stated that austenitic cast steel and 'duplex' are characterized by a similar value of abrasion wear and adhesive wear at rubbing friction. The smallest decrease in mass was shown by the cast steel in interaction with the sulfonitrided steel C55. Austenitic cast steel and 'duplex' in different combinations of friction pairs have a higher wear quality than gray cast iron EN-GJL-250 and spheroidal graphite iron EN-GJS-600-3. Austenitic cast steel and 'duplex' are characterized by a lower wearing quality than the spheroidal graphite iron with bainitic-martensitic microstructure. In the adhesive wear test using CASTROL oil the tested cast steels and cast irons showed a small mass decrease within the range of 1-2 mg.
6
Content available Effects of Cr - Ni 18/9 austenitic cast steel modification by mischmetal
Gajewski M., Kasińska J.
Archives of Foundry Engineering
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2012
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Vol. 12, iss. 4
47-52
EN
This paper presents the results of Cr - Ni 18/9 austenitic cast steel modifications by mischmetal. The study was conducted on industrial melts. Cast steel was melted in an electric induction furnace with a capacity of 2000 kg and a basic lining crucible. The mischmetal was introduced into the ladle during tapping of the cast steel from the furnace. The effectiveness of modification was examined with the carbon content of 0.1% and the presence of \delta ferrite in the structure of cast steel stabilized with titanium. The changes in the structure of cast steel and their effect on mechanical properties and intergranular corrosion were studied. It was found that rare earth metals decrease the sulfur content in cast steel and above all, they cause a distinct change in morphology of the \delta ferrite and non-metallic inclusions. These changes have improved mechanical properties. R02, Rm, and A5 and toughness increased significantly. There was a great increase of the resistance to intergranular corrosion in the Huey test. The study confirmed the high efficiency of cast steel modification by mischmetal in industrial environments. The final effect of modification depends on the form and manner of placing mischmetal into the liquid metal and the melting technology, ie the degree of deoxidation and desulfurization of the metal in the furnace.
7
Przesłanki wytwarzania staliw pod kątem jakości odlewów austenitycznych
Lis T., Nowacki K., Kania H.
Hutnik, Wiadomości Hutnicze
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2011
|
Vol. 78, nr 9
720--723
PL
Światowa produkcja stali i staliw odpornych na korozję, podczas ostatnich 25 lat, wykazuje wzrost około 5 % rocznie, z wyraźnym przyspieszeniem w ostatnich paru latach. Polska jest jednym z największych producentów staliw w Europie. Wytwarzanie odlewów austenitycznych odpornych na korozję w małych krajowych odlewniach, nie posiadających obróbki pozapiecowej, napotyka szereg trudności, m.in. uzyskania zawartości węgla na poziomie 0,02÷0,03 % C. W pracy zaproponowano algorytm optymalizacji działań technologicznych umożliwiający produkcję dobrych jakościowo odlewów austenitycznych.
EN
The world production of corrosion resistant steels and cast steels during the last 25 years has increased about 5 % a year, and has accelerated recently Poland is one of the largest producers of casts in Europe. Production of austenitic corrosion resistant casts is encounters difficulties at small domestic foundries. In the article we suggested algorithm of the optimization of the technological process enabling the production of high quality casts.
8
Content available Mechanical properties of phase constituents in selected grades of cast steel
Garbiak M., Zubko P.
Archives of Foundry Engineering
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2011
|
Vol. 11, iss. 3 spec.
57--60
EN
The nanoindentation measurements performed on three cast steels of 0.3C-30Ni-18Cr type with various content of niobium and titanium were carried out. Mechanical properties of the main phase constituents of the alloys, such as austenite, MC and M23C6 type carbides, were determined and analysed. The values of hardness (H) and Young modulus (E) for the austenite matrix were similar within the tested alloys. Essential differences (H=12÷24 GPa; E = 250÷400 GPa) were found between the carbide p hases p resent in tested alloys. The nanoindentation measurement on small particles is affected by different effects. One of these effects was excluded using numerical simulation of impressing the phase constituent into the matrix during indentation. The values of H and E obtained from simulation were: 30/450 GPa for NbC; 50/580 GPa for TiC; and 19/320 GPa for Cr23C6 respectively.
9
Content available remote Ocena wpływu makro i mikronaprężeń na powstawanie i rozwój pęknięć w staliwie austenitycznym podczas zmęczenia cieplnego. I. Makronaprężenia
Tuleja J.
Archives of Foundry Engineering
|
2010
|
Vol. 10, iss. 2 spec.
157--162
PL
W pracy oceniono wpływ makronaprężeń na pękanie elementów oprzyrządowania technologicznego eksploatowanych w piecach do nawęglania. Wyznaczono rozkłady temperatury analitycznie, stosując model ciała półnieskończonego oraz numerycznie, metodą elementów skończonych dla modelu węglika częściowo osłoniętego austenityczną osnową. Porównano rozkłady naprężeń σx, σy, σz wyznaczone metodą elementów skończonych przy uwzględnieniu wymiany ciepła oraz jednoczesnej zmiany temperatury w całej objętości przyjętego modelu obliczeniowego węglika i otaczającej go osnowy. Na podstawie przeprowadzonych obliczeń wykazano, że w obszarze przypowierzchniowym badanych elementów, w którym dochodzi do inicjacji pęknięć, temperatura podczas gwałtownego chłodzenia jest stała, stąd można wykluczyć bezpośredni wpływ makronaprężeń na ich powstawanie.
EN
In the study, the effect of macrostresses on the cracking of technological instrumentation elements used in carburising furnaces was evaluated. Temperature distributions were determined analytically using a model of semi-infinite body and numerically with the finite element method for the carbide model partially surrounded by the austenitic matrix. The distributions of stresses - σx, σy and σz - determined with the finite element method, allowing for heat exchange and simultaneous temperature change in the whole volume of carbide and its surrounding matrix adopted as a computational model, were compared. It was shown based on the carried out calculations that temperature during rapid cooling in the near-surface area of the tested elements where it comes to the initiation of cracks is constant, and therefore a direct effect of macrostresses on their development can be excluded.
10
Content available remote Ocena wpływu makro i mikronaprężeń na powstawanie i rozwój pęknięć w staliwie austenitycznym podczas zmęczenia cieplnego. II. Mikronaprężenia
Tuleja J.
Archives of Foundry Engineering
|
2010
|
Vol. 10, iss. 2 spec.
163--168
PL
W pracy oceniono wpływ mikronaprężeń na pękanie elementów oprzyrządowania technologicznego eksploatowanych w piecach do nawęglania. Doświadczalnie oceniono możliwość wystąpienia przemiany fazowej w warunkach oddziaływania podwyższonej i zmiennej temperatury w staliwie austenitycznym typu Fe-Ni-Cr-C. Numerycznie, metodą elementów skończonych, wyznaczono naprężenia strukturalne σx, σy, σz, powstające wskutek różnic, głównie w wartościach współczynników rozszerzalności cieplnej węglików i austenitu, w modelu węglika częściowo osłoniętego austenityczną osnową, podczas jego gwałtownego chłodzenia. Dla przyjętego modelu węglika, stosując hipotezę niezmienników Burzyńskiego określono obszar, w którym węglik ulegnie uszkodzeniu. Wykazano, że naprężenia strukturalne wynikające z różnic we właściwościach fizycznych faz są bezpośrednią przyczyną pękania badanych elementów.
EN
In the study, the effect of microstresses on the cracking of techno-logical instrumentation elements used in carburising furnaces was evaluated. A possibility of the appearance of phase transition in austenitic cast steel of the Fe-Ni-Cr-C type under raised and variable temperature effect conditions was evaluated experimentally. Structural stresses – σx, σy and σz, - developing due to differences, for the most part, in carbide and austenite thermal expansion coefficient values were determined numerically with the finite element method in the carbide model partially surrounded by the austenitic matrix during its rapid cooling. For the adopted carbide model, the area where the carbide will be damaged was determined using the Burzyński’s hypothesis of invariants. It was shown that microstresses resulting from differences in the physical properties of phases are a direct cause of cracking of the examined elements.
11
Content available remote Influence of the heat treatment on the microstructure and properties of austenitic cast steel
Bała P., Krawczyk J., Pawłowski B.
Archives of Foundry Engineering
|
2010
|
Vol. 10, iss. 3
35--38
EN
Exploitation investigations of a centrifugally cast pipe of austenitic cast steel indicated a significant influence of its microstructure on functional properties. Determination of the possibility of forming the microstructure and properties of the investigated cast steel by heat treatments was the aim of the presented paper. According to the Standard ASTM A 297, material from which the pipe was made is determined as HF type cast steel. The solution heat treatment from a temperature of 1080 °C was performed and followed by the microstructure observations and hardness measurements. It was found, that the solution heat treatment from this temperature will not significantly improve the material strength properties. However, it will visibly influence its fracture toughness. An influence of aging performed after the solution heat treatment on microstructure and hardness was also investigated. Cast steel was aged for 1 hour at 600 °C (solution heat treatment from 1080 °C). On the basis of the obtained results it was found, that the solution heat treatment temperature should be the maximum permissible by the Standard i.e. 1150 °C. Heating the supersaturated material (from 1150 °C) even to a temperature of 600°C should not cause the carbide precipitation in a form of the continuous network in grain boundaries, which would decrease fracture toughness of the investigated cast steel. Due to fracture toughness a service exposure of this material should not exceed 600 °C. The permissible service exposure up to 900 °C, given for this material in the Standard, is correct only on account of heat and high temperature creep resistance but not fracture toughness.
12
Content available remote Corrosion resistance of various bio-films deposited on austenitic cast steel casted by lost-wax process and in gypsum mould
Gawroński J.
Archives of Foundry Engineering
|
2010
|
Vol. 10, iss. 1
39-44
EN
This work is the next of a series concerning the improvement of austenitic cast steel utility predicted for use in implantology for complicated long term implants casted by lost-wax process and in gypsum mould. Austenitic cast steel possess chemical composition of AlSl 316L medical steel used for implants. In further part of present work investigated cast steel indicated as AlSl 316L medical steel. Below a results of electrochemical corrosion resistance of carbon layer and bi-layer of carbon/HAp deposited on AISI 316L researches are presented. Coatings were manufactured by RF PACVD and PLD methods respectively. Obtained results, unequivocally indicates on the improvement of this type of corrosion resistance by substrate material with as deposited carbon layer. While bi-layer of carbon/HAp are characterized by very low corrosion resistance.
13
Content available remote Analysis of effort of carbides and austenite in austenitic cast steel cooled violently
Tuleja J.
Archives of Foundry Engineering
|
2010
|
Vol. 10, iss. 1
205-210
EN
This work presents the analysis the effort of phases which are present in the austenitic cast steel Fe-Ni-Cr-C, applied for elements of technological instrumentation for carburising furnaces. The reduced stresses [sigma]_red in the carbides and the austenitic matrix were determined in accordance with the assumed hypotheses of effort, on the basis of the structural stresses [sigma]_x [...] calculated by the finite element method for two model location cases of the carbides towards the cast steel surface. The hypotheses referred to the crack condition were applied to evaluate the elastic carbide efforts, while for the elastic-plastic austenitic matrix - the hypotheses referred to the plasticity condition were used. There were compared the reduced stresses óred determined in accordance with various hypotheses and the correctness of their applying. It was demonstrated on the basis of the executed analysis of the effort that the carbides are destroyed only when they are not entirely surrounded by the austenitic matrix.
14
Content available remote Wpływ dodatków stopowych na temperaturę krzepnięcia staliwa austenitycznego
Garbiak M.
Archiwum Technologii Maszyn i Automatyzacji
|
2008
|
Vol. 28, nr 3
35-40
PL
W artykule przedstawiono wyniki badań, których celem była ocena wpływu niobu, tytanu i krzemu na wartość temperatury początku i końca krzepnięcia staliwa austenitycznego typu 0,3 C--30Ni-18Cr. Metodą ATD rejestrowano krzywe krzepnięcia 15 stopów zawierających 0,03÷3% Nb, 0,03÷5-1,4% Ti oraz 1,6÷4,3% Si. Wykazano, że badane składniki stopowe zwiększają zakres temperaturowy i wydłużają czas krzepnięcia. W stopach z górną zawartością wprowadzonych pierwiastków rejestrowano dwa przystanki temperaturowe i tworzenie się dodatkowego składnika fazowego w mikrostrukturze stopów.
EN
The paper presents the results of research on TDA cooling curves of austenitic cast steel 30Ni-18Cr with niobium, titanium and silicon. The liquidus and the end of solidification temperature were determined for 15 experimental alloys in which the content of alloying elements varied in a range of 0.03-3% Nb, 0.03-1.4% Ti and 1.6÷4.3% Si. It has been found that all the alloying additions decrease the liquidus and end of solidification temperature and they cause an enlargement of the solidification interval. For alloys of the highest total content of Nb, Ti and Si the second temperature arrest on TDA curve was recorded and simultaneously G phase precipitates have been observed in the microstructure.
15
Content available remote Konstruowanie odlewów pracujących w warunkach cyklicznych zmian temperatury
Piekarski B., Drotlew A.
Archiwum Technologii Maszyn i Automatyzacji
|
2008
|
Vol. 28, nr 3
95-102
PL
W artykule na przykładzie odlewanych elementów służących do uformowania i transportu wsadu w piecach do obróbki cieplnej - przedstawiono podstawowe zasady obowiązujące przy projektowaniu odlewów pracujących w warunkach cyklicznych zmian temperatury. Zestawiono wytyczne dotyczące doboru grubości i sposobów łączenia ścianek odlewów.
EN
In this paper, on an example of cast elements for charging batch in heat-treatment furnaces, the basic rules of designing of castings working in conditions of cyclic changes of temperature have been show. The guiding principles of the choice of wall thickness and wall commotions have been presented.
16
Content available remote Fracture formation in austenitic cast steel during thermal fatigue
Tuleja J.
Archives of Foundry Engineering
|
2008
|
Vol. 8, iss. 1
139-142
EN
In the paper are presented the results of numerical analyses of carburisation and thermal shock effect on fracture formation in stable austenitic cast steel of Fe-Ni-Cr-C type used in the charge-carrying elements of carburising furnaces. Using the method of finite element method, the distribution of stresses developing in carbides and their surrounding matrix were determined during rapid temperature changes. It was showed that very large tensile stresses developed in the carbides "out–coming" onto the alloy surface, regardless of the volume, type and anisotropy of properties, which could have led to their cracking as early as in the first cycles of heating and rapid cooling.
17
Content available remote Exploitation of rare earth metals in cast steel production for power engineering
Gajewski M., Kasińska J.
Archives of Foundry Engineering
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2008
|
Vol. 8, iss. 4
41-46
EN
The paper presents results of experiments carried out on industrial melts. There has been tested the REM influence on carbon properties (0.20%C) as well as austenitic cast steel Cr-Ni 18/8+Ti type. It was found that REM cause an essential improvement of cast steels impact strength and in case of austenitic cast steel – also the corrosion resistance improvement in boiling 65%HNO3 (Huey test).
18
Content available remote Creep-resistant austenitic cast steel
Piekarski B., Kubicki J.
Archives of Foundry Engineering
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2008
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Vol. 8, iss. 2
115-120
EN
The study reviews the reference literature and gives some results of own investigations concerning changes of phase composition that take place in creep-resistant austenitic cast steel of two generations due to an ageing treatment. The cast steel of the first generation contains in its chemical composition only the alloying additives like nickel, chromium and silicon. Compared with the first group, the chemical composition of the second generation cast steel has been enriched with additions of niobium and/or titanium.
19
Content available remote Fracture toughness of stabilised 0.3%C-30%Ni-18%Cr cast steel
Garbiak M.
Archiwum Technologii Maszyn i Automatyzacji
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2007
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Vol. 27, nr 1
27-32
EN
The effect of niobium, titanium and silicon additions on fracture behaviour of 0.3%C-30%Ni--18%Cr cast steel after annealing for 300 hrs at a temperature of 900°C has been investigated. The Charpy test results showed that the presence of Nb/Ti in chemical composition in combination with silicon reduces the fracture toughness of cast steel at room temperature and at 900°C.
PL
W artykule omówiono badania wpływu dodatków niobu, tytanu i krzemu na udarność staliwa 0,3%C-30%Ni-18% Cr po wyżarzaniu w temperaturze 900°C w czasie 300 godzin. Wyniki pomiaru udarności wykazały, że badane pierwiastki zmniejszają udarność staliwa zarówno w temperaturze pokojowej, jak i w temperaturze 900°C.
20
Content available remote Sample preparation vs quality of X-ray phase analysis results
Chylińska R.
Archives of Foundry Engineering
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2007
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Vol. 7, iss. 4
21-24
EN
In this study, taking as an example the creep-resistant austenitic cast steel, the results of the investigations were presented whose aim was to show what effect the specimen surface condition, discussed in terms of its roughness obtained by grinding, polishing with diamond paste, electrolytic polishing and etching, may have on the quality of results obtained by X-ray phase analysis. The preset goal has been achieved comparing the quantity and intensity of reflections on X-ray diffraction patterns obtained from the prepared specimens. The test material was cast steel containing (in wt.%): 0.29%C, 1.02%Mn, 4.36%Si, 0.007%S, 0.015%P, 17.8%Cr, 29.3%Ni, 1.59%Nb and 1.19%Ti, subjected to the process of annealing at a temperature of 850°C for 100 hours. For identification of structural constituents by the technique of X-ray phase analysis, four solid specimens were prepared. Their surfaces were successively ground, polished, and subjected to electrolytic etching. The reference sample (isolate) was obtained by the method of electrolytic extraction. In solid material the following phases were identified: Fe[gamma], NbC and G; in the isolate additionally the presence of TiC, M23C6 and [sigma] was reported. It has been proved that in the case of solid specimens partial identification of phase constituents may be carried out on surfaces subjected only to grinding with 600 grit abrasive paper without the need of any further preparation.
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