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Unalloyed cast iron materials exhibit low tribological and corrosive resistance. In this respect, nitriding has a wide range of applications for steels. In the case of cast iron, the advantageous properties of nitrided layers are impaired by the presence of graphite. Electron beam remelting of cast iron surfaces prior to nitriding removes graphite. The homogeneous ledeburitic microstructure within the approx. 1 mm-thick remelted layer enables the formation of a dense compound layer during subsequent nitriding. The main objective of this study is to investigate the nitriding mechanism of unalloyed ledeburitic microstructures. Due to the complex relationships, investigations were carried out on both conventional ferritic and pearlitic cast irons and Fe-based model alloys containing one to four additional alloying elements, i.e., C, Si, Mn and Cu. The iron (carbo-)nitride composition (γ', ε) of this compound layer depends on the gas nitriding conditions, the chemical composition of the substrates and the microstructural constituents. As a result, a schematic model of the nitriding mechanism is developed that includes the effects of the nitriding parameters and alloy composition on the phase composition of the nitriding layer. These findings enable targeted parameter selection and a further optimization of both the process and the properties. [ABSTRACT FROM AUTHOR]

The paper addresses the microsegregation of Mn, Mo, Cr, W, V, Si, Al, Cu and P in the white cast iron. Eutectic alloy with the content of 4.25% C was studied. The white cast iron was directionally solidified in the vacuum Bridgman-type furnace at a constant pulling rate v = 83 μm/s and v = 167 μm/s and at a constant temperature gradient G = 33.5 K/mm. The microstructural research was conducted using light and scanning electron microscopy. The microsegregation of elements in ledeburite was evaluated by EDS measurements. Content of elements in ledeburitic cementite and ledeburitic pearlite was determined. The tendency of elements to microsegregation was found dependent on the solidification rate. Microsegregation of elements between pearlite and cementite structural constituents has been specified. The effect of solidification rate on the type and intensity of microsegregation in directionally solidified eutectic white cast iron was observed. A different type of microsegregation was observed in the components of ledeburite in cementite and pearlite. [ABSTRACT FROM AUTHOR]

Experimental values are derived for the tribological characteristics of EN-GJV-400 cast iron, as well as its surfaces modified by melting, alloying with copper and nickel, and tungsten inert gas (TIG) welding in a high-frequency magnetic field. The latter process considerably improves the wear resistance. [ABSTRACT FROM AUTHOR]

Medium-alloy chromium-nickel cast iron with different contents of silicon and vanadium is studied. The composition of the carbide phase, the distribution of elements in the carbide phase and in the metallic matrix, and the proportion of the structural components and of the carbides are determined. The effect of the form of globular graphite on the mechanical properties of the cast iron is described. Acomposition for fabrication of wear resistant parts with a mass exceeding 100 kg is suggested. [ABSTRACT FROM AUTHOR]

The structure and mechanical properties of an ultrahigh-carbon steel modified with amorphous ferrosilicon with a low melting point are studied. The methods of x-ray diffraction, optical and scanning electron microscopy are used to study the effect of the amorphous modifier on the structure of eutectic ledeburite in the cast steel. Tests for tensile strength and impact toughness are conducted. It is shown that the mechanical properties increase as a result of the modification without subsequent heat treatment. [ABSTRACT FROM AUTHOR]

A theoretical and experimental method for predicting the technical operating life of the working body of a chisel plow is proposed, which is based on the stage-by-stage wear of working bodies: the first stage is related to the formation of the bow geometry that provides the minimum level of energy consumption for the displacement of the working body in the cultivated soil; the second stage is the translational displacement of the obtained cross-section of the cutting part to the limit condition. An analytical dependence for determining the limit value of the linear wear of the working body of a chisel plow is derived. [ABSTRACT FROM AUTHOR]

The work presents investigation results of wear resistance of steel surfaces at abrasive wear after plasma carburization for different types of surface layer structures. The optimal surface microstructure of the parts that is able to resist the effect of solid abrasive particles during operation is determined. [ABSTRACT FROM AUTHOR]

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The production of ferrous metal increased during the Roman Late Republican period, Principate and Empire. The direct bloomery process was used to extract the metal from its ores using slag-tapping and slag-pit furnaces. The fuel was charcoal and an air blast was introduced by bellows-operated tuyères. Iron formed as a bloom, often as a spongy mass of metal, which contained impurities from the smelting process, including unreacted ore, fuel, slag and fragments from the furnace walls, while the metal was often inhomogeneous with varied carbon contents. Blooms were either smithed directly into bars or ingots or they were broken up, which also allowed the removal of gross impurities and a selection of pieces with similar properties to be made. These could then be forge-welded together and formed into characteristically shaped ingots. Making steel in the furnace seems to have been achieved: it depended on the ore and the furnace and conditions within it. Surface carburization was also carried out. Iron and steel were used extensively in construction and for tools and weapons. Fire welding was often used to add pieces of steel to make the edges of tools and weapons, which could be heat-treated by quenching to harden them. [ABSTRACT FROM AUTHOR]

Directional solidification of the Fe - 4,3 wt % C alloy was performed with the pulling rate equal to v=83 μm/s. Sample was frozen during solidification to reveal the shape of the solid/liquid interface. Structures eutectic pyramid and spherolitic eutectic were observed. The solidification front of ledeburite eutectic was revealed. The leading phase was identified and defined. [ABSTRACT FROM AUTHOR]

Directional solidification of ledeburite was realised out using a Bridgman's device. The growth rate for movement sample v=83.3 μm/s was used. In one sample the solidification front was freezing. The value of temperature gradient in liquid at the solidification front was determined. Interfacial distance λ on the samples was measured with NIS-Elements application for image analysis. [ABSTRACT FROM AUTHOR]