Russian Metallurgy (Metally)最新文献

Abstract

An electron-microscopic study of the structural-phase composition of materials for late graphitizing modification of cast iron melt is carried out in the mold pouring bowl (FeSi75 lump (AO Chelyabinsk Electrometallurgical Integrated Plant (ChEMK))) and inside the mold (cast insert in the sump under the riser). The shape and location of the main phases with their individual morphological features, namely, size, casting defects, etc., are analyzed. A conclusion was made about a positive effect of ferrosilicon repeated remelting in the manufacture of the cast insert.

Abstract

The results of a set of experimental studies of the properties of epoxy–sand composites used to repair parts of road-building machines are presented. The effect of the pretreatment of the particulate filler on the properties and structure of the composite was evaluated. The stability of the epoxy–sand composites in a harsh environment (deicing agent) was studied. The friction coefficients of the epoxy–sand composites were determined. It was found that a decrease in the filler concentration provides better resistance of the epoxy–sand composites to harsh environments and the best wear resistance.

Abstract

A procedure and results of estimating the adhesion strength of a fiber–matrix system are presented. Carbon and basalt fibers are used, and a composition of epoxy resin and an amine solidifier is applied as a polymer matrix. The results of strength tests on the estimation of the adhesion strength by the pull-out method using two types of samples are presented: macro- and microsamples differ in the accuracy of determining the contact area between a fiber and the polymer matrix. The values of adhesion strength of microsamples based on elemental fibers are found to be lower than those of macrosamples, but the determination accuracy is substantially higher than that for the macrosamples.

Abstract

Data on the estimation and selection of working gases for powder plasma build-up welding are reported. Being selected appropriately, these gases protect molten metal against oxidation and stabilize arcing. The industrial use of plasma methods with a properly selected gas medium makes it possible to cover machine parts and equipment components by wear-resistant coatings. Mobile equipment for plasma build-up welding based on a KamAZ motor truck has been designed, as applied to which the thermophysical behavior of hot hydrocarbons has been considered. Recommendations for its use and operation control are given.

Abstract—A technological process of hot die forging of a crosspiece has been developed using QForm computer simulation. The influence of the technological parameters on the force parameters and the filling of the die cavity is investigated. The state of stress and the temperature fields in a forging, the optimum shape and sizes of the initial workpiece ensuring the minimum technological forces, forging passes, the optimum conditions for filling the die cavity, and forging cooling conditions are determined. The optimum forging scheme has been determined.

Abstract—The dependence of the Russian industry on the import of rare metals is considered. The volume of imports and their geographical structure, including those from the so-called “unfriendly countries,” are presented. The rare metals the prospects for replacing them with imports in the near future seem to be low are considered.

Abstract

The effect of repeated use of the chrome-calorizing powder mixture on the thickness and structure of the diffusion coating in the repair of gas turbine engine blades was investigated. The experimental study showed that reuse of the powder mixture results in a change in the mechanism of formation of the diffusion coating. The mechanism of sticking of the powder mixture during deposition of the protective coating on the turbine blades was determined.

Abstract—The features and prospects of using nickel superalloys as structural materials for advanced reactor plants, in particular, molten salt reactor (MSR) are considered. The main limiting factors impeding the use of nickel superalloys under MSR operating conditions are considered. Information on new high-temperature EK198 and EK199 alloys, which have high radiation resistance and improved mechanical characteristics, is provided.

Abstract—The pricing environment of rare earth metals, which has a multidirectional character for different rare earth products, is reviewed. The potentially recoverable value of 1 kg rare earth metals is calculated for various foreign and Russian deposits. The level of unit cost of the rare earth products, which is taken as a basic comparative indicator, is revealed. An efficiency coefficient for manufacturing commercial rare earth products for various deposits has been proposed and calculated.

Abstract—The research on ultrasonic riveting has revealed that the application of vibrations enables a significant decrease in the riveting force and changes the deformation characteristics of a rivet. Initially, a rivet shank undergoes upsetting, and the gap between the rivet and the installation hole is filled with the deformed metal, and a closing head then forms. The joints formed by ultrasound-deformed D18 alloy rivets exhibit a considerable increase in the shear force.