Coercive force of double layer ferromagnetic materials

Peculiarities of the coercive force (CF) measuring of inhomogeneous ferromagnetic materials, in particular layered ones, are considered. The concept of effective CF of layered ferromagnetic materials is introduced. The analysis of the magnetic fluxes distribution in a double layer ferro-magnetic material during its reversal magnetization by an attachable transducer with a U-shaped core made of soft magnetic material is carried out. An analytical expression of the effective CF for such class of materials for the case of the same layers’ thickness and linear approximation of their demagnetization curves is obtained. It was found that the effective CF of a double layer ferromagnetic material is determined not only by the CF of its individual layers, but also by the values of their residual induction. Experimental verification of the obtained results was performed on experimental samples, which were collected from steel 08kp (sample # 1) and steel St3 (sample # 2) plates. Each of the samples was a stack of 6 plates each measuring 87×50×1 mm. With tight compression of the plates and complete elimination of the gaps between them, these samples can be considered as single layer ferromagnetic structures with a thickness of 6 mm. To model a double layer ferromagnetic material with the same layer thickness, sample № 3 was used. Its the upper part consisted of the three steel 08kp plates and the lower part – of the three steel St3 plates. To measure the magnetic parameters of these samples the KRM-Ts-MA type magnetic analyzer was used. The device permit to measure the CF, residual induction and other parameters of the hysteresis loops of ferromagnetic materials in the closed magnetic circuit by attachable type transducers with U-shaped core. The transducer used with the magnetic analyzer during the experiments had poles with an area of 16×32 mm and the distance between the edges of the poles: inner – 32 mm, outer – 64 mm. It is shown that the discrepancy between the calculated value of the effective CF of the double layer ferromagnetic material (sample # 3) from steel 08kp and St3 according to the obtained expression and the measurement results is about 3%. This confirms the adequacy of the proposed model of reversal magnetization of double layer ferromagnetic material and the correctness of analytical calculations.

Synthesis and experimental studies of the method of manufacturing screw spirals with a rotating plug with feasibility study

The structural synthesis of methods of winding screw spirals using the method of hierarchical grouping by means of morphological analysis is carried out and a number of alternatives that allowed to create the improved way of winding screw spirals with rotating plug is obtained. On the basis of the conducted multifactor experiment the study of torque of the process of screw workpiece calibration per step was performed and the regression dependence was obtained to determine the influence of winding width, wedge angle and winding thickness on the torque of the calibration process. It is established that calibration process of the turn of screw workpiece per step depends on the width, thickness of the spiral and the angle of the wedge of the device. With increasing inclination of the wedge of the device and the thickness of the winding, for the material steel 08kp, the torque increases and reaches 79 N m. It is established that the dominant factor influencing the value of torque is the angle of the wedge of the device, and the least influential is the winding width. The technical and economic estimation of the method of winding screw spirals with rotating plug is carried out and found that the annual economic effect, when replacing the basic version of winding screw spirals (winding on the frame) on the design (winding with rotating plug), when operating equipment in one shift is 16995.79 UAH.

EVALUATION OF THE RESIDUAL STRESSES LEVEL FORMED DURING THE COOLING OF THE TITANIUM-STEEL BIMETAL

The level of internal stresses arising in the titanium VT1-0 + steel 08kp bimetal during cooling was estimated by methods of finite element modeling. It is shown that the intermetallic layer formed during diffusion annealing leads to a sharp local increase in the residual internal equivalent Mises stresses with a slight decrease in the stresses normal to the interface.

Microalloying of low carbon steel with boron and a method for determining the effective concentration of dissolved boron

Goal. The effect of boron on the properties of steel is considered. It has been established that hardenability improves due to the influence of boron, which is not bound in oxides, nitrides or other compounds. This boron is in solid solution in austenite and is called an “effective” boron. The mechanism of increasing the hardenability of steel due to such boron is associated with inhibition of the occurrence of crystallization centers of ferrite and bainite. Methodology.The effective fraction of boron in dissolved state in austenite is determined by the method of electrochemical phase analysis. The microalloying of low-carbon steel 08kp with boron is tested on industrial heats under conditions of Martin workshop of JSC «Zaporozhstal». Smelting and teeming of steel were performed according to the requirements of operating technology. The input of ferroboron into metal took place while letting out the heats into the ladle after completion of the ferromanganese input. All the experimental heats were blown through in the ladle with argon to appearance of the furnace slag. For microalloying the ferroboron of the grade FB20 was used. At the by-sheet sorting of the experimental ingot of the heat (the average content of boron in the heat - 0,00138%), sampling of metal rolled stock was brought off on 5 horizons by the height. In every sample the chemical analysis for the content of boron was executed in 3th points, corresponding to the edge of roll, ¼ on the width and axis. Results of the chemical analysis are presented in the table 1. At the average content of boron in the heat - 0,00138%, the content of boron was distributed along the height and width of the ingot was distributed from 0,0008% (-0,00058%) to 0,0024% (+ 0,00102%). Results. The technology of microalloying low-carbon steel with boron has been mastered with obtaining a guaranteed content of at least 0,0008%. Putting a ferroboron into the ladle with a flow rate of 0.26 - 0.31 kg / t followed by purging the metal in a ladle with pure argon provides the boron content in the steel 0.0009 - 0.0015%. The absorption of boron during microalloying depends on the fractional composition of boron-containing material. For a fraction of less than 3 mm, assimilation is 29%, and for a fraction of 5-10 mm, 76% of the assimilation values obtained for an optimal fraction of 20-40 mm. Boron in 08kp steel increases the tensile strength by 4.5% and the yield strength by 2.6% compared with the average values of this steel without boron.

Forming a structure of the CoNiFe alloys by X-ray irradiation

The experimental data of electrodeposition kinetics researches and structure formation of ternary CoNiFe alloys deposited onto low-carbon steel 08kp in the presence of X-rays are presented. Relations of deposit rate, current efficiencies, element and phase compositions of CoNiFe coatings formed from sulfate baths with respect to cathode current densities (0.5–3[Formula: see text]A/dm[Formula: see text], electrolyte composition and irradiation were obtained. It is shown that, the CoNiFe coatings deposited by the electrochemical method involving exposure of the X-rays are characterized by more perfect morphology surfaces with less developed surface geometry than reference coatings. The effect of the X-ray irradiation on the electrodeposition of CoNiFe coatings promotes formatting of alloys with increased electropositive component and modified phase composition.