Powder Wire Research Articles

Employing powder wire with SK40 filler in the ladle-furnace unit at OAO EMZ

Employing powder wire with SK40 filler in the ladle-furnace unit at OAO EMZ

More efficient production of thin-walled pipe and shells for powder wire

More efficient production of thin-walled pipe and shells for powder wire

Improved use of powder wire in steel metallurgy

Ladle treatment of hot metal by magnesium-bearing powder wire is in increasing use at metallurgical enterprises, since it does not involve large capital and operating expenses and it ensures effective desulfurization, stability of the results, and considerably reduced toxic emissions [1]. This technology is used today at OAO Mariupol’skii Metallurgicheskii Kombinat im. Il’icha, OAO Tulachermet, OAO Lipetskii Metallurgicheskii Zavod Svobodnyi Sokol (LMZSS), and elsewhere [2, 3]. At OAO LMZSS, ladle treatment of hot metal by magnesium-bearing powder wire is included in the production cycle for commercial cast iron and cast-iron pipe. In the blast-furnace shop, a push-rod system is installed in the region of the casting machines; both commercial iron cast in pigs and hot metal sent to the pipe-casting shop for further treatment in induction furnaces and pipe casting undergo desulfurization in 100-t ladles. In the mixer department of the pipe-casting ship, where necessary, the hot metal undergoes desulfurization in 30-t ladles to ensure a sulfur content of less than 0.012%. In the modification section, the hot metal is treated in 7-t ladles for 5‐10 min after discharge from the induction furnaces. After treatment, the ladle with the hot metal is sent on a trolley directly to the section for centrifugal pipe casting [4]. The technology ensures a stable residual-magnesium content of more than 0.025% throughout the pipe-casting cycle, permits considerably more efficient use of the magnesium, and significantly reduces the costs of modification; the pipe obtained meets all the standard requirements regarding microstructure and mechanical properties. Magnesium‐staurolite wire is used for desulfurization, and ferrosilicon‐magnesium wire is used for modification. The characteristics of ladle desulfurization of hot metal by magnesium‐staurolite/ferrosilicon‐magnesium wire in 30-, 100-, and 140-t ladles are shown in the table. (The data for 140-t ladles are taken from [4].) The results indicate that desulfurization is highly effective when using magnesium-bearing powder wire. Ladle treatment of hot metal by magnesium‐silicon alloy considerably improves the efficiency of magnesium utilization. The cost of removing 0.01% S is $0.5‐ 1.0/t if the initial content is ≥ 0.03% S, and $1.2‐1.6/t if the initial content is ≤ 0.02%. The degree of magnesium assimilation for the different groups of hot metal at OAO LMZSS is 90.2‐98%; the coefficient of magnesium utilization in sulfur removal K Mg‐S is 28.8‐46.4%; the magnesium consumption is 0.3‐0.5 kg/t. In steel production, treatment of the melt with calcium-bearing reagents is very effective and, in view of non-Russian experience, essential. In the production of high-quality metal for major gas and oil pipelines, shipbuilding, and the construction industry, ladle treatment with calcium-bearing powder wire is a key part of steel production and an effective means of improving the properties of liquid and solid steel. Calcium has a significant influence of the kinetics of steel reduction, refining, modification, and microalloying [2, 5]. At metallurgical enterprises where the melt is treated with calcium, the casting of steel reduced by aluminum is not a problem. The negative influence of alumina in the melt and in the final product is eliminated; the content of harmful impurities, oxides, and sulfides is reduced; and the composition and shape of the nonmetallic inclusions are modified. This improves the steel quality. The relative elongation is increased by 10‐15%, and the impact strength of thick rolled sheet is increased (by a factor of 1.5‐1.8), with simultaneous increase in strength (by 5‐10%) and decrease in the cold-brittleness threshold (by 15‐20 ° C). The surface

Improving the manufacturing technology for thin-walled pipe and small-diameter shells

In arc welding, attention focuses on the electrode materials, based on powder wire. Benefits of powder wire include a high melting rate, its universal applicability for different welding and soldering systems, generation of specified properties of the metal, and high quality of the weld joints. In powder-wire production technology, continuous roller shaping of the packed tubular shell is followed by drawing to the specified size, with winding of the final product in coils. One of the main operations is shaping of the tubular shell. To evaluate the influence of the contact interaction on the shaping and motion of the billet through the working grooves, a method of determining the contact area of the roller with the pipe blank for two-radius grooving has been developed [1]. In determining the shaping energy and forces for the pipe blank, the total vertical force is the key factor. The shaping force ( in the i th cell for two-radius grooving of shaping-mill rollers is

Correlations between In-Flight Particles, Splats and Coating Microstructures of Ni20Cr Thermally Sprayed by Flame and Arc Spray Processes

Correlations between in-flight particle, splat and coating microstructure of thermally sprayed Ni20Cr were investigated. Flame spray and arc spray systems were employed for spraying Ni20Cr powder and Ni20Cr wire, respectively. The results showed that the arc spray process produced a broader size distribution for both in-flight particles and splats compared to flame process. Flower-like splat morphology was obtained from the arc spray whereas a pancake-like splat was obtained by flame spray. Ni20Cr coating sprayed by arc process had a denser microstructure, lower porosity and better adhesion at the interface. This could be due to the higher temperature and velocity from the arc spray process enhancing the melting and adhering for coating formation.

Effect of the laser fusion of electrometallized coatings of the Fe-Cr-B-Al system on their corrosion resistance

We studied the effect of laser treatment of electric arc coatings produced of powder wires of the Fe-Cr-B system on the changes in their structure, electrolytic potential, and polarization currents. We additionally introduced aluminum, nickel, and copper to the charge of these coatings. Laser treatment was realized by means of Nd: YAG laser radiation. We have shown that the addition of a small amount of these elements to the coating under study in different ways affects the character of formation, structure, and electrochemical characteristics of the fused layer. In particular, copper and nickel additions increase the fluidity of the coating. The parameters of laser treatment affect strongly the uniformity of the distribution of elements in the fused zone. In the case of alloying with copper, the nonuniformity of their distribution is more pronounced, which can exert a slight negative influence on the corrosion characteristics of the coating. Aluminum addition improves the corrosion resistance of laser-modified coatings.

Heat Resistance of Electric Arc Coatings Made of Fe–Cr–B–Al Powder Wire

Electric metallized coatings made of Fe–Cr–B–Al powder wire possess a high heat resistance at 700–800°C at the level of compact 08Kh13 material. During 5–7 h, the coating is subjected to intense internal oxidation, which prevents oxygen penetration into the base material. To obtain heat-resistant electric metallized coatings of powder wire, it is necessary to form a structure with controlled heterogeneity by adding a certain quantity of Al and Mg to the charge.

Degradation of Bi-2223/Ag-wires composite bulk exposed to repetitive temperature change

Repetitive temperature cycles may cause the damage in the superconducting bulk, and thus the effect of repetitive temperature change was studied. A Bi-2223/Ag wires composite bulk was prepared by stacking the calcined powder and pure Ag wires alternately followed by sintering. The specimen was exposed to the repetition of temperature changes between 77 and 300 K up to 400 times. Homogeneous external magnetic field generated by Helmholtz coils was applied at each cycle, and the surrounding magnetic fields were measured. The shielding effect was evaluated by the integration of the flux density and the standardization by the value in the normal conducting state. The shielding effects were compared with those for sintered BSCCO specimen without Ag. Degradation was small in the Bi-2223/Ag wires composite bulk.

Tribological properties of arc sprayed coatings obtained from FeCrB and FeCr-based powder wires

The technology of wear resistant coatings and new powder wire composites has been developed. New coatings with low porosity and small grains were obtained by arc-spraying of FeCrB+Al and FeCr+Al+C powder wires in a steel cover. A modified arc spraying torch was used. The initial phase contents of coatings and their changes in the subsurface region during friction processes were studied by X-ray diffractometry (XRD). Wear tests with the block-on-ring configuration at boundary lubrication and friction in an abrasive-oil mixture under normal pressure at 5 MPa have been performed. Results for sprayed coatings of both systems showed their high wear resistance.

Gas shield powder wire welding of SPW steels

Gas shield powder wire welding of SPW steels

Structure and Distribution of Components in the Working Layer Upon Reconditioning of Parts by Electric-Arc Metallization

Reliable data on the structure of the deposited layer are very important due to the considerable instability of the process of deposition of coatings by the method of electric-arc metallization and the strict requirements for reconditioned crankshafts. The present paper is devoted to the structure of coatings obtained from powder wire based on ferrochrome-aluminum with additional alloying elements introduced into the charge.

Appearance and redistribution of internal stresses in coatings in the process of their application

We describe an original method for experimental determination of the formation of and changes in internal stresses that appear in electrometallized coatings in the process of their application. The regularities of changes in internal stresses depending on the thickness of coatings and composition of the blend of a powder wire are investigated. It is shown that residual tension stresses in coatings relax by means of plastic strain of low-strength structural components and/or due to the initiation and growth of cracks in brittle components. The characteristics of strength and crack resistance of coatings can be considerably improved by optimizing the composition of the blend of the powder wire.

Use of powder wire to correct the manganese content of steel

Use of powder wire to correct the manganese content of steel

Extrafurnace carburization of steel with powder wire

Extrafurnace carburization of steel with powder wire

Alloying of steel with vanadium using powder wire

Alloying of steel with vanadium using powder wire

Out-of-furnace treatment of steel and iron by powder wire

Out-of-furnace treatment of steel and iron by powder wire

Nonfurnace desulfurization of iron with powder wire

Nonfurnace desulfurization of iron with powder wire

Improving the wear resistance of suction dredges

1. An industrial procedure for electrofacing by a powder wire of special composition has been developed to produce a wear-resistant coating up to 5 mm thick on the components of suction dredges. An increase of 4–6 times is achieved in the time to failure of the faced components, while the cost of these operations does not exceed the price of the initial article. 2. It is expedient to use the facing procedure to strengthen new components under plant conditions and to restore worn parts at the site where the suction dredges are operated. The Scientific-Production “Spetsstal'” can perform work on electrofacing with the required materials, equipment, and technical accompaniment, and organize the strengthening of components at the plant. 3. The installation of a three-channel suction dredge with effective water protection of components from abrasive wear while eliminating overflow of slurry into the pump and increasing the efficiency of the unit on the whole is proposed. The proposal is recommended for development and implementation.

Dependence of the level of residual stresses on the composition of coatings and conditions of electric arc metallization

A modified method for determining the stresses that appear in electrically metallized coatings in the process of spraying followed by cooling is suggested. Using this method, we study the dependence of internal stresses on the efficiency of the spraying process, coating thickness, and powder wire charge composition. According to the results of these investigations, all the coatings under consideration can be classified into four groups. It is shown that the residual stresses in the coatings relax as a result of plastic deformation of low-strength structural components and/or as a result of crack initiation and growth in brittle components. Depending on the correlation between the plastic and brittle phases, one observes either a single crack or numerous cracks. The strength and crack-resisting characteristics of electrically metallized coatings can be improved significantly by optimizing the powder wire charge composition.

BiCaSrCuO superconductors: Powder synthesis, wire fabrication and hot extrusion experiments.

Abstract BiCaSrCuO and BiPbCaSrCuO powders were synthetized. Different research methods (SEM, EDS, XRF, XRD, DTA) were used to characterize the bulk specimen and wires. Resistance and current density were measured as a function of temperature. The ceramic products contained several phases. Lead containing specimen gave the best results and the synthesis was easily reproducible.