Microstructure and mechanical properties of ADI depending on austenitization methods and parameters

Ductile iron was quenched using two-variant isothermal transformation. The first treatment variant consisted of one-phase austenitization at a temperature t = 830, 860 or 900 C, cooling down to an isothermal transformation temperature of 300 or 400 C and holding from 8 to 64 minutes. The second treatment variant consisted of two-phase austenitization. Cast iron was austenitizied at a temperature t = 950 C and cooled down to a supercritical temperature t = 900, 860 or 830 C. Isothermal transformation was conducted under the same conditions as those applied to the first variant. Ferrite cast iron was quenched isothermally. Basic strength (Rp0.2 Rm) and plastic (A5) properties as well as matrix microstructure and hardness were examined. As a result of heat treatment, the following ADI grades were obtained: EN-GJS-800-8, EN-GJS-1200-2 and EN-GJS-1400-1 in accordance with PN-EN 1564:2000 having plasticity of 1.5-4 times more than minimum requirements specified in the standard

Modeling of Railway Wheels Made of Austempered Ductile Iron

A person is forced to travel constantly throughout its entire life. The more modern the society, the greater the pace of life, and the greater the need to be present in many places that are distant from each other. Rail transport occupies second place in this regard, after air transport. This means of transportation has many advantages, however the time of travel requires continuous improvement, in particular, to match the competition. One factor limiting the speed of travel is inter-operation between the wheels – rail kinematic pair. When rolling on a rail, a wheel is subject to wear, which unavoidably leads to its degradation. Frequent damage to both the wheel and the rail necessitates consideration of this problem. Because any changes to the rail are very expensive and time-consuming, this paper focuses on possible changes to the wheel. This paper is of an analytical nature and is based on sources in the literature, as well as on own simulations. The objective of the paper is to indicate the advantages of using ADI (Austempered Ductile Iron) as a material for the wheel of a railway rolling stock through analysis of available scientific materials and analysis based on a conducted simulation. The application of ADI on a large scale would certainly make a large impact on the development of railway engineering, significantly reducing the costs of manufacturing the product and its future exploitation

Wykresy CTPc żeliwa sferoidalnego z węglikami

This work presents continuous cooling transformation diagrams for different kinds of carbidic nodular cast iron. We investigated the cast iron, chemical composition of which in nodular cast iron allows the obtainment of a metal matrix which consists of: pearlite, upper bainite and its mixture with lower bainite, ausferrite and martensite when the casts were cooled in the mold. The influence of the rate of cooling on the obtained microstructure and hardness of the casts was shown. The work describes the influence of the alloy additives on the curves of austenite decomposition in the carbidic nodular cast iron. Diagrams were plotted which enable an understanding of the kinetics of the transformations of austenite in carbidic nodular cast iron. The diagrams also indicate the possibility of obtaining pearlite, bainite, martensite and ausferrite with the established chemical composition and the wall thickness of the cast.W pracy przedstawiono wykresy CTPc różnych rodzajów żeliwa sferoidalnego z węglikami. Zbadano żeliwo o składzie chemicznym zapewniającym uzyskanie w żeliwie sferoidalnym osnowy metalowej złożonej z: perlitu, bainitu górnego oraz jego mieszaniny z dolnym, ausferrytu i martenzytu przy studzeniu odlewów w formie. Pokazano wpływ szybkości studzenia na uzyskiwaną mikrostrukturę i twardość odlewów. Opisano wpływ dodatków stopowych na krzywe rozpadu austenitu w żeliwie sferoidalnym z węglikami. Opracowane wykresy umożliwią poznanie kinetyki przemian austenitu w żeliwie sferoidalnym z węglikami oraz ocenę możliwości uzyskania perlitu, bainitu, martenzytu i ausferrytu przy zadanym składzie chemicznym oraz grubości ściany odlewu

Comparing the possibilities of austenite content determination in austempered ductile iron

The article presents various methods for assessment of the austenite volume fraction in Austempered Ductile Iron (ADI). Tests were carried out on two types of ADI, i.e. unalloyed and alloyed with the addition of 0.72% Cu and 0.27% Mo, heat treated under different conditions of isothermal transformation to obtain different austenite volume fractions. The test material was then subjected to metallographic examinations, X-ray diffraction (XRD) analysis, an analysis using the author's genuine programme of artificial neural networks, image analysis and magnetic measurements. The results were compared with each other indicating the possibility of a quantitative measurement of austenite and other phases present in cast iron. It was found that different methods of measurement are not fully consistent with each other but show similar results of the austenite content

Eutectoid Reaction Ar1 of Cast Iron GJS-400-15 in Isothermal Conditions

This scientific paper presents the research on influence of austenitizing temperature on kinetics and evolution of the spheroidal plain cast iron during eutectoid reaction in isothermal conditions. The cast iron has been austenitized in temperatures of 900, 960 or 1020°C. Therewere two temperature values of isothermal holding taken into consideration: 760 or 820°C. The order of creation of reaction products and their morphology have been analyzed. The particular attention has been paid to the initial stage of transformation. The qualitative research has been executed using the transmission electron microscope (TEM), as well as quantitative research (LM). The influence of austenitizing temperature has also been determined on transformation kinetics and structural composition. It was found that the increase of austenitizing temperature is conductive to the initial release of structures by metastable system. A reduction of time was observed of the initial stage of transformation at temperature close to Ar12 with its simultaneous elongation at temperature close to Ar11, with an increase of austenitizing temperature. The dependences obtained by the metallographic method confirm the prior results of dilatometric research of eutectoid reaction

Wpływ temperatury łamania na udarność żeliwa ADI

W publikacji podjęto próbę zbadania wpływu temperatury łamania w temperaturach 20°C, 0°C i – 20°C, na udarność żeliwa ADI. Do otrzymania żeliwa ADI użyto dwa wytopy żeliwa sferoidalnego różniące się składem chemicznym. Pierwszy zawierał oprócz pierwiastków podstawowych dodatkowo 0,48% Cu, drugi zaś 0,51% Cu i 0,72% Ni. Wariant obróbczy polegał na jednostopniowym austenityzowaniu w temperaturze tγ = 900°C, podchładzaniu do temperatury przemiany izotermicznej 375°C i wytrzymywaniu w czasie od 15 do 90 min

Characteristics of products received during grinding in hammer mills

W pracy przedstawiono charakterystykę produktów otrzymanych podczas rozdrabniania ziarna pszenicy i kukurydzy za pomocą rozdrabniacza bijakowego. Jako parametry zmienne zastosowano zmienną długość roboczą bujaka: 173, 177, 181 mm.The characteristics of products obtained during grinding of wheat and corn using a hammer mill is presented in the paper. A variable working length of ram (173, 177, 181 mm) was used as a changeable parameter

Continuous Cooling Transformation (CCT) Diagrams Of Carbidic Nodular Cast Iron

This work presents continuous cooling transformation diagrams for different kinds of carbidic nodular cast iron. We investigated the cast iron, chemical composition of which in nodular cast iron allows the obtainment of a metal matrix which consists of: pearlite, upper bainite and its mixture with lower bainite, ausferrite and martensite when the casts were cooled in the mold. The influence of the rate of cooling on the obtained microstructure and hardness of the casts was shown. The work describes the influence of the alloy additives on the curves of austenite decomposition in the carbidic nodular cast iron. Diagrams were plotted which enable an understanding of the kinetics of the transformations of austenite in carbidic nodular cast iron. The diagrams also indicate the possibility of obtaining pearlite, bainite, martensite and ausferrite with the established chemical composition and the wall thickness of the cast

Characteristics of phosphate conversion coatings

Celem pracy jest przedstawienie produkcyjnych i użytkowych charakterystyk fosforanowych powłok ochronnych. Opisano wybraną metodę wytwarzania fosforanowej powłoki ochronnej oraz podano przykład jej zastosowania. Przedstawiono przykładową pracującą linię fosforanowania oraz opisano cechy uzyskiwanej powłoki.A main aim of the paper is to present the production and usable characteristics of phosphate conversion coatings. The paper describes a selected method of protective coating manufacture and gives an example of its application. An example of working phosphatizing process line is shown and the formation of coating after successive trials is described