Abstract: The transverse magnetic field (TMF) use allows to obtain follow effects: increasing the electrode melting coefficient, reducing the base metal penetration depth and grinding the weld metal structural components. The paper analyzed the existing literature data about the TMF influence on the refinement of the weld metal structure. It is experimentally shown that the alternating TMF influence of 6 Hz frequency reduces the grain size of weld metal is almost twice in comparison with the welding process without the TMF influence at submerged arc welding of plates of austenitic steel type 12X18H9T (X10CrNiTi18-9). The average grains size is 7-6 index, when welding without the TMF influence and the average grains size of the weld metal corresponds to 8 index, with separate inclusions of grains with 7 index when welding with the TMF influence. This is should increase the yield strength value of the weld metal in accordance with the data of Hall – Petch.
Abstract: Mechanical engineering is one of the most dynamically developing industries in many countries. Welding at the same time is one of the main processes of metal working in various industries, especially in mechanical engineering. The World Health Organization considers welding works to be harmful and dangerous for health. The present paper identifies the main factors leading to injuries during welding works at a stationary workplace. A causal tree for a welding incident has been devised and analyzed. Probability of an incident was estimated by using the expert evaluation method. It was found out that machine injury is the most probable type of incident. The aim of this article is to work out welding incident mitigation measures in the industrial sphere based on the incident probability assessment
Abstract: An interrelation between structural features, microhardness and wear resistance was studied in the coatings obtained by non-vacuum relativistic electron beam cladding of chromium and titanium carbides powder mixture on low carbon steel. Five coatings differing in the amount of the entered energy were investigated using scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX), indentation tests and wear resistance measurements. It was found that the concentration of alloying elements both in solid solution and eutectic as well as the volume fraction of eutectic are the main structural characteristics which defines the microhardness of the coatings. The distribution of TiC phase plays a key role in the resistance to wear.
Abstract: This paper presents an overview of applying nano-and ultra-disperse powders as modifiers in various procedures of arc welding, as well as in electro-slag welding and plasma powder spraying. Consideration of some methods of embedding nano-and ultra-disperse powders into a liquid weld pool is provided.
Abstract: Crack resistance of welded joints is one of the most important indices of service reliability of critical designation structures. The purpose of the research is the establishment of the influence of technological modes, hybrid laser-arc welding of high strength steel NA-XTRA-70 on the formation of structure in the metal welded joints, as well as analysis of the influence of this structure on their crack resistances. For the experiments the laboratory setup has been developed on which the experiments were carried out in the technological scheme that provides the location of the consumable electrode arc at a certain distance in front of the laser beam in the welding direction. Nd: YAG-laser DY 044 of company ROFIN (Germany) was a laser radiation source. Power for consumable electrode arc was carried out by welding generator PSG-500. Investigations of structural-phase changes in weld metal and HAZ were carried out by means of optical microscopy (optical microscope Versamet-2 and Neophot-32), microhardness was measured using M-400 gage of Leco company at 0.98N loading. Fractographic investigations were carried out by scanning electron microscopy (scanning electron microscope SEM-515 of PHILIPS company, Netherlands) on fractured specimens of welded joints, made as a result of impact bend tests. An analysis of crack resistance of the welded joints was carried out under different conditions of test temperatures. It was based on experimental data, received by a quantitative fractography method. It is shown that metal of a welded joint produced by hybrid laser-arc welding at Vw = 72m/h rate has mainly failure of ductile nature after external loading. This indicates sufficient level of crack resistance and further working capacity under operation conditions.
Abstract: The article is devoted to the problems of fractioning the general abrasive mass into the fractions of certain shape grains. The methods of separation of bulk materials have been analyzed. The designs are considered and the operating principle of the original units for abrasive separation is described. The revealed regularities at the separation of abrasive masses of various granularities are presented.
Abstract: This article develops a fundamentally new approach in the selection of optimal methods for restoring of worn surfaces of agricultural machines’ tools with the formation and application of technological repair units. Based on the systematization and linkage of modular worn-out surfaces, their operating conditions, technological environment and the choice of their optimal combinations, it found a low-cost method of restoring details with white cast iron to gain a necessary quality of a new surface layer.
Abstract: The paper discusses the results of the numerical simulation of high-speed impact effect of compact projectiles made of steel and tungsten alloy with steel obstacles of equal mass. The obstacles have different initial porosity of the material. Conducted the final evaluation of the penetration speed of the projectile depending on the porosity of the obstacle and the initial speed of the shock interaction. The initial impact velocity range from 1 to 16 [km/s]. The destruction, melting and evaporation of the interacting bodies are taken into account. The analysis of porosity influence evaluation of obstacles material revealed that the protective advantage of porous obstacles disclose at the higher impact velocities, greater than 1.5 [km/s] for steel strikers and 2 [km/s] for projectiles of tungsten alloy. The more impact velocity the more protective effect of porous obstacles.
Abstract: The use of computational methods allows us to significantly shorten the time required for researches and save welding and other consumables. In addition, the computational methods used in studies make it possible to demonstrate the obtained results with a high degree of accuracy. Computational methods are based on computer-aided mathematical modeling of welding processes. Mathematical modeling is applied specifically to develop models adequately describing various welding processes or interrelation between those processes. The article describes the model that demonstrates the distribution of temperature fields in butt joints during the arc welding with pulsed electrode wire feeding.