Key Engineering Materials Vol. 684

Abstract: Shown are results of theoretical and experimental research of force modes and limit possibilities of the first and subsequent operations of combined isothermal drawing of axisymmetric parts made out of anisotropic materials through conic and radial matrixes in the mode of short-time creeping. Studied was straining of anisotropic material under conditions of short-time creeping. We ignore the elastic components of strain. We introduced potential straining speeds for an anisotropic body under conditions of short-time creeping. Found was the effect of technological parameters, anisotropy of mechanical properties, and of age-hardening upon the stress condition, the force modes of the operation, and upon the design margin of strain during the first and subsequent operations of combined drawing. Experimental research was carried out for the force conditions and possible limits of straining during the first and second operations of combined isothermal drawing with convex-face and conic matrices in the mode of short-time creeping. Comparing the results of theoretical and experimental research for force modes and strain limits during the first and subsequent operations of combined drawing has shown their satisfactory similarity (up to 5% - 10%).

Abstract: Provided is a mathematical model of stretching operation involving wall thinning of axisymmetric blanks of anisotropic materials. Obtained were correlations which can be used to evaluate the kinematics of the material flow, the stress and strain states of the blank, the force conditions and the limit possibilities of drawing involving wall thinning of thick-walled anisotropic axisymmetric blanks. Comparison of results of theoretical calculation against experimental data have shown satisfactory similarity. The maximal difference between the theoretical and experimental data does not exceed 10 percent. The research results were used in developing the technological process to manufacture thick-walled cylindrical blanks for critical axisymmetric items made of steel 11YUA.

Abstract: Authors of article offer the mixed technology of receiving the facilitated screening casing from aluminum foil of 0,15÷0,2 mm thickness by the means of magnetic-pulse welding preforming (MPWP) combining thermal and force impact on processed material.The physical entity of MPWF is described, parameters of the modes of welding are specified, metallographic researches of a zone of welded connection are conducted.The press of double action realizing static and impulse loading on processed material is developed.

Abstract: The report shows the classification of methods of high-voltage capacitor welding (HVCW) with magnetic drive pulse applied to the preparation of joints such as "rod - drive" of non-ferrous metals and alloys. Researches of processing methods of process of HVCW are provided. The ranges of energetic, geometrical parameters are defined and dependences of durability of welded connections are given. The hypothesis is offered and usage considerations on HVCW are made.

Abstract: The production of a new type of hard alloys by explosive compaction of chromium carbide (Cr₃C₂) and titanium powder mixtures was investigated. The phase composition of the fabricated alloys was studied using scanning electron probe microanalysis. The chemical composition of the alloy components does not change, and no redistribution of the elements was observed. The formation characteristics of the interfaces between the material components during shock wave processing were investigated using electron microscopy. The explosion compaction of high melting carbide and metal powder mixtures results in the formation of consolidated hard alloys during the compaction stage.

Abstract: The tribological characteristics of the Cr₃С₂–Ti system hard alloys produced by the explosive compaction of powders containing 20, 30, 40, and 50 vol. % of the titanium binder are investigated. The general approach to selecting the optimal structure and properties of wear-resistant hard alloys for manufacturing the slider bearing parts working in conjunction with silicified graphite under water lubrication conditions is formulated. It is shown that, to attain the highest antifriction characteristics and minimal wear of the friction unit, the alloy should have the maximally possible hardness with the minimally admissible specific volume of a carbide phase in the material structure. It is established that such alloys have higher antifriction characteristics and wear resistance than silicified graphite and the Cr₃C₂–20% Ni-type materials produced by conventional methods.

Abstract: There are the results of computer simulating using DEFORM-2D specialized software and experimental researches during the pressing of aluminium alloys tubes with conical-stepped needles. On the basis of the experiment mathematical planning and dividing coordinate grid the influence of the taper angle and needle position to the pressing stress and the intensity of deformation relative to the die parallel land was established. The optimal parameters determining methods of conical-stepped needles geometry were proposed.

Abstract: Computer analysis of distribution of stress intensity and strain intensity in different cross sections of plastic deformation region and in finished material in the course of hot extruding process was carried out. By means of the finite element method in the Deform-2D program influence of small extrusion ratio value on stress-strained state of large 250mm to 500mm dia. bars in 7075 high-strength Aluminium alloy was established.

Abstract: The correct choice of a metal separation method, in particular for thin-walled tubes, is vital for technical and economical performance indices in aircraft building. The most important selection criteria are separation quality, the amount of waste, possibility to consolidate operations and equipment efficiency. These factors require ongoing development & enhancement of tube separation methods. Waste-free technological processes like torsion tube sectioning are preferred. As the result of the extended research of tube separation process using torsion with active counterpressure, particularly the effect of structural parameters on cut quality, optimum tolerance for clearance fit between dies was defined. Compliance with recommended practices during equipment manufacturing will let cut quality reach the value peculiar to the quality value of sectioning method of separation using metal-cutting equipment. Herewith manufacturing becomes waste-free and quarantines calibration of sections adjacent to the cut.

Abstract: This article considers the method of determining the parameters of the rheological properties of material of titanium alloy BT6 used in aircraft engine technology, under face milling. Calculations were carried out in CAE system Deform using FEM - model.