The study of the complex thread knurling process

The study carried out to research a manufacturing process of long products for mining industry by a method of cold knurling, in particular, on a stud of a self-drilling bolt used for strengthening of mountain rocks. The solution of the task was obtained by mathematical simulation of the knurling process in the FE software package that allows establishing stress-strain state parameters necessary to analyze forming and loading of the process. According to the R&D carried out on a basis of the two-rolled screw thread rolling machine was developed a technological process for which the knurling rollers were design and created. The manufactured pilot batch of items that's meeting the requirements for such type of anchors speaks of capability to maintain low-series production of self-drilling fasteners based on the complex profile cold knurling method of a long billet. © Published under licence by IOP Publishing Ltd

EBSD mapping of herringbone domain structures in tetragonal piezoelectrics

Herringbone domain structures have been mapped using electron backscatter diffraction (EBSD) in two tetragonal piezoelectrics, lead zirconate titanate, [Pb(Zr,Ti)O<sub>3</sub>] and bismuth ferrite – lead titanate, [(PbTi)<sub>0.5</sub>(BiFe)<sub>0.5</sub>O<sub>3</sub>]. Analysis of the domain misorientations across the band junctions shows that the structures correspond very well to crystallographic models. High resolution mapping with a 20 nm step size allowed the crystal rotation across one of these band junctions in lead zirconate titanate to be studied in detail and allowed an improved estimation of the peak strain at the junction, of 0.56 GPa. The significance of this for crack nucleation and propagation in such materials is discussed

Studying damage accumulation in martensitic corrosion-resistant steel under cold radial reduction

Cold radial reduction of specimens made of the Kh17N2 corrosion-resistant martensitic steel is studied on a lever-type radial-forging machine (RFM). The mechanical properties of the deformed specimens, the "damage accumulation - strain" relation in the specimens are obtained with the application of hydrostatic and fractographic methods for fractured specimens. The damage of the Kh17N2 corrosion-resistant steel is evaluated as a result of an experimental study considering the data of simulation by a complex finite element model of cold deformation on a lever-type RFM. © 2017 Author(s)

Effect of tetragonal distortion on ferroelectric domain switching: A case study on La-doped BiFeO3-PbTiO3 ceramics

The ferroelectric and piezoelectric properties of (1-x)BiFeO3-xPbTiO(3) (BF-PT) ceramics were investigated as a function of tetragonal distortion. The latter was adjusted by employing La-doping (0-30 at %) while keeping the material near the morphotropic phase boundary by varying x between 0.35 and 0.46. This allows changing the c/a ratio of tetragonal BF-PT in the range from 1.10-1.01 and consequently alters the level of compatibility stresses. It was found that the c/a ratio has a significant influence on domain switching as inferred from electric field induced polarization, strain hysteresis, and Rayleigh measurements. Specifically, a threshold c/a ratio of about 1.045 was identified below which the electric field induced domain mobility increases sharply.open342

Research of Load Distribution between Working and Backup Rolls of Sheet Levelling Machine with Regard to Gaps and Heat Strain

The article addresses to distribution of loading between working and backup rolls of sheet levelling machines taking into account presence of initial gaps between them and heating that occurs during the straightening process, which is especially important in case of the high-temperature straightening. For levelling machines with a single row of backup rolls calculated dependencies were obtained to evaluate loads suffered by backup roll taking into account factors under this study and the analysis of results for the 9-roll straightening machine were carried out. The analysis showed a significant overload suffered by backup rolls. © Published under licence by IOP Publishing Ltd

Experimental Research of the Hot-Rolled Pipe Wall Sizing Process at the Reeling Mill of Pipe-Rolling Plant-140 in Conditions of Product Mix Extension

This experimental study was conducted on the equipment of pipe-rolling plant-140 with an automatic mill in order to give a qualitative and quantitative evaluation of the parameters which define the pipe wall sizing process in reeling mills. During investigation values of the power parameters of the process were recorded for different sizing routes. Conclusions about the special features of the wall sizing process and feasibility of extension of the reeling mill process capabilities were formulated. © Published under licence by IOP Publishing Ltd

The research on the levelling process of thick slabs based on the electric motor parameters monitoring

For the leveling machines in conditions of a small batch production which is typical for manufacturing sheets of non-ferrous alloys, in particular, titanium, the rollers heating is very influential. In order to expand the technological possibilities of the main equipment in non-stationary thermal working conditions of rollers that is an actual new scientific problem the experimental study of the loading in the hot leveling of slabs made from hardly-deformed titanium alloys was carried out on the 9-roll leveling machine. To achieve this goal the methodology of the complex experimental study of the actual loading definition of the leveling machine drive was developed. The experimental study was carried out for alloys Ti6Al4V (Vt-6s) and PT-3V with the initial heating temperature of the rolled product from 750 to 850 C. The slab leveling process was logged for slabs with the thickness from 20 to 68 mm, the width from 985 to 1720 mm by the number of passes through the leveling machine from 2 to 8. The treatment and analysis of experimental data was conducted on the basis of which the summary of permissibility of assortment expansion of leveling slabs has been formulated. © Published under licence by IOP Publishing Ltd