Formation of high-carbon abrasion-resistant surface layers when high-energy heating by high-frequency currents

The paper shows the possibility of carburization of low-carbon steel surface layers using high-frequency currents. The mathematical modeling of carburization using high-energy heating by high-frequency currents (HEH HFC) has been carried out, the temperature fields formed during the given processing have been calculated, as well as the structural changes in the surface layers have been simulated. The features of the structure formation in the surface layers of low-carbon steel after carburizing via HEH HFC have been determined by optical and scanning microscopy, which is confirmed by the computational models. The rational mode of fusion via HEH HFC has also been determined (power density of the source q[s]=(1.5...4.0)•10{8} W m{-2}, (the relative travel speed of parts V[p]=5 ... 100 mm /sec), with forming the compressive retained stresses in the surface layer ([sigma][RS]=-300...-400 MPa)

The method of quantitative automatic metallographic analysis

A brief analysis of the existing softwares for computer processing of microstructure photographs is presented. The descriptions of the the software package developed by the author are demonstrated. This software product is intended for quantitative metallographic analysis of digital photographs of the microstructure of materials. It allows calculating the volume fraction and the average size of particles of the structure by several hundred secants (depending on the photographs resolution) in one vision field. Besides, a special module is built in the software allowing assessing the degree of deviation of the shape of different particles and impurities from the spherical one. The article presents the main algorithms, used during the creation of the software product, and formulae according to which the software calculates the parameters of the microstructure. It is shown that the reliability of calculations depends on the quality of preparation of the microstructure

Formation of high-carbon abrasion-resistant surface layers when high-energy heating by high-frequency currents

The paper shows the possibility of carburization of low-carbon steel surface layers using high-frequency currents. The mathematical modeling of carburization using high-energy heating by high-frequency currents (HEH HFC) has been carried out, the temperature fields formed during the given processing have been calculated, as well as the structural changes in the surface layers have been simulated. The features of the structure formation in the surface layers of low-carbon steel after carburizing via HEH HFC have been determined by optical and scanning microscopy, which is confirmed by the computational models. The rational mode of fusion via HEH HFC has also been determined (power density of the source q[s]=(1.5...4.0)•10{8} W m{-2}, (the relative travel speed of parts V[p]=5 ... 100 mm /sec), with forming the compressive retained stresses in the surface layer ([sigma][RS]=-300...-400 MPa)

The features of steel surface hardening with high energy heating by high frequency currents and shower cooling

The paper examines the process of surface hardening of steel 45 with the help of high energy heating by high frequency currents with simultaneous shower water cooling. We theoretically justified and experimentally proved a possibility of liquid phase forming in the course of heating not on the surface, but in the depth of the surface layer

Research on the possibility of lowering the manufacturing accuracy of cycloid transmission wheels with intermediate rolling elements and a free cage

Purpose: In the present work, different combinations of fits and accuracies, in relation to the profiles of mating parts, have been analysed in order to assess the degree of the engagement of transmissions that contain intermediate rolling elements. The aim of this work is to determine which fits have decreased accuracy, but nevertheless provide a minimum manufacturing clearance for the transmission engagement in order to reduce the cost of parts production. Methods and materials: Considering the normal probabilistic distribution law in relation to the obtained dimensions of the manufacturing equipment, a combination of fits were selected using the incomplete interchangeability method, taking into account the peculiarities of the cycloid engagement in transmissions with intermediate rolling elements (IRE). Results: Having studied various combinations of fits of parts that are engaged in transmissions with intermediate rolling elements and a free cage (IREFC), a combination of fits for a "ring, rolling-element cam" were determined, in which a technological clearance of 3 mu m is formed in the engagement. At the same time, cycloid disk profiles are manufactured according to the 9th tolerance grade, which reduces the laboriousness and cost of the production. Discussion. When reducing the manufacturing accuracy of cycloid disks, it is possible to obtain both very ample clearances and significant negative allowances. For example, having manufactured a ring with the H9 fit, rolling elements with h6 and a cam with js9, the maximum manufacturing clearance can reach 0.086 mm, while the clearance limits vary from 0.025 mm to 0.061 mm. Additionally, if mating parts are manufactured using a combination of K9-h6-js9 fits, a negative allowance varying from 0.014 mm to 0.026 mm will emerge in the engagement. Both described cases are unacceptable because both ample clearances and large negative allowances will negatively influence the working capacity of the mechanism. However, it is possible to select a combination of fits using the 9th tolerance grade of the basic parts, by which the parts will contact in the range from a small negative allowance of 1 mu m to a clearance of 3-4 mu m. Furthermore, if this is considered, taking into account the machine settings, it is possible to obtain parts according to the 9th accuracy tolerance grade and, at the same time, provide a clearance in the engagement that is almost equal to zero. Moreover, such a combination of fits is relevant for any transmission with IRE. This is a positive result because it reduces the laboriousness when manufacturing parts and, at the same time, provides high accuracy of the mechanism. Conclusions: It has been established that when lowering the accuracy of manufacturing transmission parts with IRE, both clearances and negative allowances may occur in the engagement, depending on the combination of fits. At the same time, it is possible to select such a combination of fits, by which the parts manufactured according to the 9th tolerance grade, will provide almost zero clearance of the engagement of the transmission. In this way, it is possible to reduce the cost of manufacturing the parts for gears with intermediate rolling elements and, at the same time, maintain a high accuracy of the transmission mechanism.Web of Science121art. no.