The optimization of modes of submerged arc surfacing with application of external magnetic field over the layer of alloying charge of caterpillar machine running gear parts was carried out. The influence of external axial magnetic field parameters and powders of silicon carbide SiC and aerosil SiO2, introduced with the charge, on hardness and microhardness of the deposited metal was studied. During experiments the concentration of silicon compounds in alloying charge, number of deposited layers, deviation in the arrangement of the latter relatively to the arc axis as well as induction of the external magnetic field were changed. The regression dependence of hardness on surfacing mode parameters for two types of charge is presented. The software complex was designed intended to determine the parameters of arc surfacing mode according to the proposed scheme to provide the maximum effect of using external influences. 11 Ref., 1 Table, 3 Figures.
Given are the results of study of structure, hardness and relative wear resistance of surface layers of parts, restored by submerged arc surfacing with addition of powdered materials and superposition of external magnetic axial field. Using powders of silicon carbide SiC and aerosil SiO2 the paste-like mixture on the base of GF-021 primer was prepared and deposited by beads along the surfacing direction. During experiments the composition of mixture, number of layers being deposited, eccentricity in arrangement of layers relative to electrode wire axis, as well as induction of external magnetic field were varied. Coming from the obtained results, the highest values of hardness of the deposited metal were observed at B = 20-50 mT. Optimum pitch in deposition of layers is 4-6 mm. Hardness is growing with increase of number of layers being deposited. Regression equations of mentioned relationships are presented. Due to external magnetic field it became possible to decrease the heat effect on added powdered materials without melting of their particles. Analysis of microstructures proves the effect of magnetic field on crystallization. The uniform distribution of particles of powdered material was occurred, grain number reached 10-12 over 6-8 initial one. Wear tests revealed the least losses in mass of specimens, deposited with addition of SiO2 particles. In this case the allowable plastic deformation and maximum increase in hardness of surface layers are occurred. The practice of restoration surfacing of parts in different branches of industry predetermined a great number of directions in development and improvement of methods of traditional arc consumable electrode surfacing. In different times the technology and equipment were offered, which allowed increasing the efficiency of surfacing, providing the deposition of layers in multi-layer coatings in various spatial positions and of different chemical composition, including composite ones [1].At general tendency of applying non-deficit and inexpensive surfacing materials for restoration and hardening of parts, the main difficulty is encountered in attaining the high wear resistance of contact surfaces being restored. The increase in service characteristics of the deposited working layer is attained usually by the selection and optimizing the chemical composition of electrode or filler surfacing materials and, when necessary, by subsequent heat treatment [1][2][3][4][5].To increase the term of service of parts, operating under conditions of abrasive wear, the updating of installation for automatic submerged arc surfacing was made, technology of surfacing over the layer of alloying charge was developed, surfacing of specimens was performed by the developed technology, microstructure and wear resistance of deposited specimens were examined.The principle of offered changes consists in superposition of controlling axial magnetic field on welding arc during surfacing, which has a retarding effect on rate of molten metal flows in a pool and decreases the depth of base met...
Abstract. It is possible to increase the MAG-welding efficiency by controlling the electrode metal mass transfer at the reduction of discharge coefficient on spattering by influence of longitudinal magnetic field on the arc. The paper identifies a range of longitudinal magnetic field frequencies and induction which provide the discharge coefficient reduction of the electrode metal; it has also been found the characteristics of their mutual influence on electrode metal mass transfer process; mathematical models correlating the frequency and induction of longitudinal magnetic field length with loss coefficient of electrode metal on spattering are presented; technological recommendations, the implementation of which will allow to improve the efficiency of MAG-welding in industrial environments, are given.
The hydrodynamic processes modelling in the weld pool under the influence of the electromagnetic bulk force was carried out. For the approximation of the model equations the finite difference method was used. The resulting system of linear algebraic equations was solved by simple iteration. The finding served the basis for determining the optimal scheme supply of powder material adding for the modification and alloying of the weld (build-up) metal in the presence of an external magnetic field.
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