Electrical Discharge Machining by Structural-Steel Electrodes

Russian Engineering Research - An approach is outlined to selecting conditions of electrical discharge machining such that coatings with the required functional properties are formed on the working...     

Deformation Behavior of Metastable Austenitic Steel at Low and Moderate Temperatures

Metal Science and Heat Treatment - The TRIP effect and deformation behavior of metastable austenitic steel were studied under tension in the temperatures range from –120 to +200°C. The...     

Effect of pulse current on deformability, structure, and properties of NbTi alloy superconductor

The effect of pulsed current on the deformability, structure, and properties of a superconductor based on the Nb-47 wt % Ti alloy after electroplastic deformation is studied. It is shown that the use of a pulsed current during rolling makes it possible to produce a nanocrystalline structure in the alloy and improve its microhardness, as well as to reveal the electroplastic effect in it. It is found that electroplastic deformation does not suppress the superconductivity effect.     

Effect of the Relaxation Modulus on The Shape of the Stress—Strain Diagram of an Oriented Amorphous-Crystalline Polymer

In analyzing the stress—strain diagrams in the region of significant, but not yet destructive mechanical effects, it is necessary to take into account relaxation of applied stress. A method is proposed for calculated verification of the correlation between the stress—strain diagram and simple relaxation for = const. The method can also be used to refine the numerical values of the parameters of the model of physicomechanical properties selected.     

Microstructures and properties of ultrafine-grained pure titanium processed by equal-channel angular pressing and cold deformation

Equal-channel angular pressing (ECAP) has been used to refine the grain size of commercially pure (CP) titanium as well as other metals and alloys. CP-Ti is usually processed at about 400 degrees C because it lacks sufficient ductility at lower temperature. The warm processing temperature limits the ability of the ECAP technique to improve the strength of CP-Ti. We have employed cold deformation following warm ECAP to further improve the strength of CP-Ti. Ti billets were first processed for eight passes via ECAP route Bc, with a clockwise rotation of 90 degrees between adjacent passes. The grain size obtained by ECAP alone is about 260 nm. The billets were further processed by cold deformation (cold rolling) to increase the crystalline defects such as dislocations. The strength of pure Ti was improved from 380 to around 1000 MPa by the two-step process. This article reports the microstructures, microhardness, tensile properties, and thermal stability of these Ti billets processed by a combination of ECAP and cold deformation.     

Modification of aluminum antifriction alloys by carbon nanomaterials

A procedure is developed for modification of the near-surface layers of AO-20-1 alloy (AlSn20Cu, GOST Standard 14113–78) by carbon nanotubes at a depth of 2 μm. Data on the depth distribution of carbon across the near-surface layer are obtained. Mechanical and tribological tests of the modified layer are performed. It has been found that the hardness of the near-surface layer increases by 10–60% at a depth up to 1 μm and the friction coefficient decreases by ∼25 %.