


卷 63, 编号 5-6 (2019)
- 年: 2019
- 文章: 31
- URL: https://journal-vniispk.ru/0026-0894/issue/view/15020
Article
Metallurgist Volume 63, Number 5



Improvements to Mixing of Natural Gas and Hot-Air Blast in the Air Tuyeres of Blast Furnaces with Thermal Insulation of the Blast Duct
摘要
Using natural gas as an additional fuel in a blast furnace is known to reduce coke consumption during blast-furnace production. In a standard tuyere, the hot blast pushes the natural gas up against the surface of the blast duct, resulting in poor mixing between the natural gas and the hot blast, which in turn leads to incomplete combustion and pyrolysis of the natural gas. One approach for improving mixing between the natural gas and the hot blast is to modify the blast-channel geometry.
An engineering design solution was proposed, and the gas dynamics, thermal conditions, and stress/strain state of the air tuyere for this solution were analyzed via ANSYS modeling. Toroidal protrusions on an insert near the outlet of the air tuyere (swirlers) or on the gas inlet nozzle flange (rim) were considered; these protrusions also protect the insert against premature damage in areas subject to the most severe mechanical damage.
The following assumptions were made: The model scope includes both the fluid medium within the blast duct and the thermal insulation insert, i.e., this can be thought of as a conjugate heat exchange problem, and heat transfer to the cooling system water was taken into account using the generalized boundary conditions.
We show that modifying the insert geometry so that there is a protrusion on the working surface or installing a rim in the area where the insert starts to show damage, will increase mixing of the natural gas into the blast air and during combustion. This then increases the blast temperature at the tuyere outlet, which in turn increases the natural-gas flow rate and reduces coke usage. A similar result was achieved for wear on the insert.



Calculation and Analysis of the Relationship Between the Efficiency and Position of Electric Arcs and Power Consumption in Electric Arc Furnaces (EAF) of Smaller and Larger Capacity. Part 2. Calculation and Analysis of the Relationship Between Position of Arcs, Walls and Power Consumption
摘要
The power consumed during the melting process by a small-capacity DSP-5 furnace was analyzed. For each melting stage, the arc efficiency values of DSP-5 furnaces and average arc efficiency of the melting process (ηAM = 0.57) were calculated. The arc efficiency of the small-capacity furnaces is considerably lower than that of the modern large-capacity DSP-120 furnaces (ηAAV = 0.78). One cause of the lower arc efficiency of the small-capacity furnaces during furnace charge melting and arc burning inside the wells is the small distance between the arcs and the lining of the furnace walls. Another cause of the lower arc efficiency of the small-capacity furnaces during the liquid-phase periods of the melting process is the large exposed portion of the arc, no deep arc immersion into slag, and no slag foaming in the furnace. The low arc efficiency of the small-capacity furnaces leads to a significant specific power consumption during melting (700–750 kW·h/t), which is 1.9 to 2 times greater than that of the modern DSP-120 furnaces (375 kW·h/t). By using slag foaming devices in the small-capacity furnaces, it becomes possible to increase the average furnace arc efficiency of the melting process to ηAM = 0.72–0.74, while reducing the specific power consumption during melting to 400–420 kW·h/t.



Experience of Mastering in NLMK Dansteel Production of Arctic Usage High-Strength Microalloyed Steels F240, F460, and F500 for Shipbuilding and Marine Structures
摘要
Shipbuilding remains one of the most metal-consuming segments of the transport industry. For various types of vessels there is a trend of a successive increase in specifications for the specific volume of freight transport that predetermines an increase in the use of materials for construction, including thick steel plate. Considering the general trends in development of the thick plate market for shipbuilding, NLMK DanSteel has mastered production technologies for rolled product up to 35 mm thick produced from low-carbon microalloyed extra high-strength steels F420, F460, F500 intended for vessels of various types for Arctic application. Pilot plant, certified and industrial batches of heavy plates have shown a high level of strength, low-temperature impact strength at – 60°C, and a high level of welded joint mechanical properties employing various welding methods with heating input in the range from 15 ± 1 to 50 ± 2 kJ/cm. The results obtained provide NLMK DanSteel with favorable certification test results for production of extra high-strength grades F420, F460, F500 and their analogs in thickness up to 35 mm according to the IACS rules and confirm the quality of heavy plates in accordance with the requirements of DNV-GL and other marine certification association classification programs and standards.



Production of Permanent Magnets for Magnetically Hard Alloys Using Rare-Earth Metals
摘要
A requirement for improving powder metallurgy technology of alloys for permanent magnets containing rare-earth metals based on the use of secondary resources and a replacement of rare-earth metals and fine control of the semifinished products chemical composition is demonstrated. These approaches are realized successfully in the preparation of Nd–Fe–B system magnetically hard materials by a binary mixture method using rare earth metal hydrides and their alloys. Analysis of the magnetic properties of Sm–Co–Cu–Fe–Zr system permanent magnets according to the results of the primary ingot chemical composition control minimizes production costs.



Development of Manufacturing Technology for a Continuously-Cast Wheel Billet with a Controlled Aluminum Content
摘要
The quality of railway wheels significantly affects the economy and security of railway transportation. In order to improve the properties of railway wheels steel is used currently with a controlled aluminum content. A feature of this steel is the increased risk of forming large alumina non-metallic inclusions. Nonmetallic inclusions in the defective and defect-free zones of a rejected wheel are studied. The causes of defect formation and a new comprehensive technology of smelting are determined, and ladle treatment and continuous casting of steel are developed, which provide avoidance of forming these defects.The main essence of the technology is the diffusion deoxidation of metal with slag of optimum composition, control of aluminum content during ladle treatment, and use of aluminum exclusively for steel alloying.



Structural and Analytical Evaluation of the Strain Intensity and its Components During Cross-Roll Piercing at Different Feed Angles
摘要
Strain intensity and its components during cross-roll piercing at different feed angles were evaluated using a combined structural/analytical method. Commercially pure aluminum ingots of 60 mm diameter and 300 mm length were pierced to produce shells of 64.6 ± 0.5 mm diameter and 21.3 mm wall thickness at feed angles of 10, 12, 14, 16, and 18°. It was established that the shear component of strain intensity responsible for the formation of helical fiber macrostructure is predominant. The distribution of strain intensity through the wall thickness is characterized by a significant gradient that decreases as the feed angle increases. The feed angle is an effective factor that controls the process and determines the magnitude of strain intensity (its shear and linear components) and its uniform distribution throughout the wall thickness.



Study of the Effect of Composition and Thermal Deformation Treatment on Properties of Ferritic Steels Microalloyed with Titanium and Niobium. Part 1. Microstructure Characteristics
摘要
The effect of composition and thermal deformation processing (finishing temperature of rolling and coiling, cooling rate after rolling) parameters on the mechanical properties and structure of advanced Ti, Mo micro-alloyed structural (automobile sheet) ferritic steels is studied. It is established that the strength characteristics of steel increase regularly with increasing Ti content within appropriate limits and additional microalloying with molybdenum. The resultant structural state is primarily determined by the cooling rate after steel hot rolling. At relatively low values of 10–15 °C/sec polygonal ferrite is formed, and on increasing up to 30 °C/sec formation of a high dislocation acicular ferrite is observed. The expediency of reducing carbon content to 0.04–0.06 wt.% is demonstrated.



Structure, Mechanical Properties and Fracture Surface Features of Structural Steels Subjected to Deformation-Heat Treatment
摘要
A comparative study is made of the structure, mechanical properties and crack growth micromechanisms of 09G2S, 25 and 35X steel pipes after different versions of deformation and heat treatment, including cold plastic deformation of highly tempered material by radial forging and subsequent annealing. It is established that the maximum strength of the test steels is achieved after cold radial forging (CRF) with a degree of deformation of 55% and subsequent annealing at 300 °C. It is shown that CRF and annealing at 600 °C leads to formation of an ultra-fine-grained structure as a result of which reliability properties are achieved similar to a highly tempered condition with retention of improved strength properties. Features of the structure are revealed that is formed during CRF. The micromechanism of crack growth after heat and deformation-heat treatment is studied. Analysis is provided for elements of the failure surface after dynamic tests.



Advances in Materials Science and Engineering: Prediction of AISI 304 Stainless Steel Pipe Deformation by FEM Simulation
摘要
The high quality standards required for metal forming call for compliance tests aimed to guarantee that such standards are met. Such tests often imply a waste of time and of economic resources. In particular, when stainless steel pipe forming is considered, many factors need to be taken into account. This paper analyzes the effect of different process parameters and geometrical constrains on the cold forming of austenitic stainless steel pipes by the finite element method (FEM). The results of such analysis will allow one to map the effect of different parameters.



Influence of Atomic and Molecular Hydrogen in Silumins Melts on Their Mechanical Properties
摘要
We study the influence of gas porosity caused by the presence of dissolved hydrogen on the mechanical properties of Al–Si alloys. The results are obtained by testing cast samples with identical contents of hydrogen and a given (atomic or molecular) form of hydrogen inclusions. The dependence of the mechanical properties of alloys on the density index is statistically established. It is shown that if the density index increases and hydrogen is released in the atomic form, the mechanical properties remain practically unchanged, whereas the presence of hydrogen in the molecular form in silumin deteriorates the mechanical properties of the metal.



Processing of the Silver–Zinc Crust of the Product of Refining of Raw Lead in a Copper-Smelting Converter
摘要
We present the results of industrial testing of the technology of processing of silver–zinc crust obtained in the process of refining of raw lead from silver in a copper-smelting converter. We perform the tests for two versions of charging of dried crust into the converter: either into the empty converter prior to pouring matte from the smelting of secondary copper-containing raw materials in a shaft furnace or during the period of conversion after obtaining white mat. In the case of charging over the white mat, we get the slags that are poorer in all analyzed metals, whereas the yield of silver and gold into copper blister is higher. According to data of balance smelting, the direct yields of silver and gold from all types of processed raw materials into blister copper are 96.72% and 97.76%, respectively.



Technology for Extracting Manganese from Vanadium Converter Slag After Leaching Vanadium
摘要
New technology is developed for preparing pure vanadium pentoxide from vanadium-containing metallurgical slag. As a result of the selective extraction of vanadium from calcined slag, solid residues containing from 7 to 10% of manganese are formed, which are suitable for extraction. A study of the mineralogical composition of solid residues shows that manganese is found in cakes in the form of MnCO3. An aqueous solution of sulfuric acid is adopted as the leaching agent. According to our data, the maximum solubility of manganese sulfate was 484–500 g/dm3 at T = 25 °C, 5 g/dm3 H2SO4. Considering these data, a study is made of leaching Mn from solid residues with aqueous solutions of H2SO4. Extraction of Mn from solid residues into the solution is 75%, and additional extraction of vanadium remaining in cake is up to 50%. The complex solutions obtained by leaching, containing Fe3+, V5+, Al3+, Si4+, are purified by feeding them to a fresh portion of cake at pH 4–4.5 and Mn is precipitated from solution by using (NH4)2CO3 to form MnCO3. The washed and calcined residue contains pure Mn3O4. The main production scheme for comprehensive treatment of vanadium slag with preparation of V2O5, Mn3O4, MgO, (NH4)2SO4 from solution, and complex master alloys from solid residues is presented.



Metallurgist Volume 63, Number 6



Improving the Performance of Hot-Blast Stoves at EVRAZ ZSMK
摘要
A gas mixing station for admixing natural gas to the blast-furnace gas for heating the hot-blast stove was developed and put into commercial operation at BF No. 2 of EVRAZ ZSMK.



Characteristic Features of the Gas Injection Process in Oxygen Converters That Use Iron-Containing Slag Produced During Steel Smelting
摘要
We describe the characteristic features of the steel smelting process in the 160-metric-ton converters at EVRAZ Consolidated West Siberian Metallurgical Plant JSC for the case where 10–50% of the solid metal charge consists of ferrous converter-slag waste products. Information on the chemical composition of the slag materials and the metal and slag components of the slag/scrap mixture was combined with the scrap consumption rate to quantitatively estimate the change in fundamental process statistics. The parameters of the traditional oxygen-injection process for the 160-metric-ton converters were compared against those for the technology to be discussed in this paper. Both the decrease in the concentration of non-ferrous-metal impurities and the required impurity removal levels at the exit from the converter are specified. The oxidative metal refining production data for the 160-metric ton converters at EVRAZ Consolidated West Siberian Metallurgical Plant JSC and the cost reductions from slag/metal scrap usage indicate that the process is economically promising.



Study of Hydrodynamic Processes in a Steel-Pouring Ladle During Steel Flushing with Inert Gas
摘要
The effect of flushing molten metal with inert gas in a steel-pouring ladle on steel quality is considered. Hydrodynamic processes during metal flushing in a steel-pouring ladle are modeled in a computer. A hydrodynamic picture and the rate field in a ladle vertical cross section are obtained.



Improving the Performance of the Reheating Furnace of the EVRAZ ZSMK Ball-Rolling Mills
摘要
Measures were developed to reduce the fuel consumption by the walking-beam furnace of the EVRAZ ZSMK ball-rolling mill based on an analytical review of modern technical solutions for fuel saving in ferrous metallurgy heating equipment. The thermal analysis performed confirms the effectiveness of the measures.



Mastering of the Technology of Assembling of Composite Mill Rolls Under the Conditions of Rail and Structural Steel Shop at the JSC “EVRAZ ZSMK”
摘要
We develop a technology of assembling of composite mill rolls for the universal stands of the rail and structural steel shop at the JSC “EVRAZ ZSMK.” The proposed technology is based on the method of thermal shrink-fitting, including the application of bandage made of cast iron. The investigations are carried out to determine the optimal temperature and time parameters of the process of assembly.



Development of Advanced Calibrations for Point and Wing Rails in a Universal Rail and Structural Steel Mill
摘要
We presented the results of scientific and practical investigations of the technology of rolling of asymmetric rail sections, namely, of point and wing rails, performed on a universal rail and structural steel mill. The detected disadvantages are described according to the initial calibration and the causes of formation of the surface defects in the course of rolling of these profiles are established. The results of the performed analysis made it possible to develop calibrations for the analyzed asymmetric rail sections with evaluation of the stressed state of the metal in the course of rolling.



Mastering of New Rebar Profiles and Roll Materials in the Rolling Production of the EVRAZ ZSMK
摘要
The 250-1 continuous small-section mill of the JSC “EVRAZ Joint West-Siberian Metallurgical Plant” is specialized in manufacturing rebars No. 10 and No. 12 and equal angles Nos. 2–4 from workpieces with cross sections 100 × 100 mm in size. The production of rebars from carbon and low-alloy steels was mastered according to the standards of Europe, South-East Asia, and America. The production of rebars is performed both by the slitting process and without longitudinal slitting of the breakdown bars. The durability of the rebar roll passes of the finishing stands is, to a great extent, determined by the shape of grooves made at the bottom of the streams and used to form transverse ribs. The lowest durability of the passes of finishing stands is observed in the case of rolling of sections with crescent edges. In these passes, we observe the fractures of the working surface accompanied by the formation of cracks and crumbling. We tested cast iron of different grades intended for rolls of the finishing group with a minimal Shore hardness equal to 60. The best operating parameters were obtained for rolls made of nodular cast iron and alloyed with chromium, nickel, molybdenum, and vanadium.



Study of Grinding Ball Quality Properties During Manufacture in a Screw Rolling Mill
摘要
The governing effect of macrostructure quality on impact resistance is established by experiment for grinding balls 50 and 60 mm in diameter prepared by screw rolling. It is shown that presence of flakes significantly reduces grinding ball impact resistance regardless of their quenched microstructure parameters. In this case there is no significant effect of ball microstructure parameters after heat treatment on their impact resistance.



Mold Oscillating System with Optimized Non-Sinusoidal Oscillation Profile
摘要
A mold oscillating system for continuous casting machines has been developed based on a nonsinusoidal oscillation profile with an online oscillation control capability. A new type of the mold oscillating system is proposed comprising two servomotor-driven eccentric shafts. The principle of operation of a non-sinusoidal oscillation system is described. Based on the analysis of the non-sinusoidal oscillation waveform expressed as a piecewise linear function, the angular speed of a servomotor necessary to realize such oscillations was determined. A procedure for calculating process parameters was developed. The model of synchronized control of the casting speed and oscillation frequency was optimized and process parameters were calculated for the deviation factor of 20% and amplitude equal to 4 mm. The mold oscillating systems of sinusoidal and non-sinusoidal type were compared. The advantages of the non-sinusoidal type of oscillating system were shown, which include a decrease in depth of the oscillation marks on the surface of continuous-cast billet, an improvement in the mold-ingot lubrication conditions, and higher quality of continuous-cast billets.



Correlation of 12% Chromium Ferritic-Martensitic Steel Heat Resistance with Supercooled Austenite Stability Indices
摘要
Development of new heat-resistant ferritic-martensitic steels with 12% chromium designed for operation at 700–720 °С is a complex multifactorial task. The main characteristics of such steels that define the possibility of their application at elevated temperature are high values of strength within the temperature range of 20–720 °С, and high values of creep resistance at temperatures of 650 °C and above with a satisfactory ductility level (at least 6–12% at 20–720 °С). A significant amount of time is required in the case of large range of steels investigated to determine the abovementioned properties. An important task is finding readily and quickly obtained properties by which it is possible to estimate the level of steel heat resistance properties. Diagrams for isothermal decomposition of supercooled austenite are analyzed and equations are found in the present work for their connection with yield strength and creep strength of the materials studied.



Study of the Effect of Composition and Thermal Deformation Treatment on Properties of Ferritic Steels Microalloyed with Titanium and Niobium. Part 2. Phase Precipitate Characteristics*
摘要
The effect of composition and thermal deformation treatment parameters (temperature for the end of rolling and strip winding on a coil, cooling rate after rolling) on mechanical properties, microstructure, and characteristics of precipitates (type, amount, size, morphology, distribution) in advanced ferritic automotive sheet steels is studied. It is demonstrated for the first time that these steels make it possible to obtain simultaneously high strength, ductility and formability due to a homogeneous fine ferritic microstructure additionally strengthened by volumetric system of nano-sized carbide precipitates. It is shown that the contribution to steel strengthening due to the formation of phase precipitates can reach significant values of more than 300 MPa. The main features of phase precipitate, microstructure, and property formation of ferritic steels are established.



Increase in Efficiency of Heat Treatment of Large-Sized Mill Rolls by Simulating Thermal Conditions of Hardening
摘要
The paper offers a review of the current technologies of induction heating utilized during heat treatment of mill rolls. It is shown that designing the equipment and heat treatment technology with induction heating of the mill rolls is important, first of all, to ensure high quality of heat treatment. In this case, it is necessary to comply with the following requirements: provide minimum deviations of hardness from the required values along the length of the roll body and through the depth of the hardened layer, and eliminate dangerous (thermal and structural) stresses leading to roll destruction during or after the heat treatment. These problems cannot be resolved without computer simulation. A universal method of digital design and control of thermal conditions of the induction heating equipment is considered, which ensures high quality of heat treatment of the rolls.



Distribution of Antimony in Copper-Zinc Concentrate Metallurgical Processing Products
摘要
The distribution of antimony in sulfide copper-zinc concentrates processing products manufactured according to a production scheme including autogenous smelting, matte conversion to blister copper, and flotation extraction of metals from slags, is evaluated. The main products concentrating antimony concern autogenous smelting and conversion dust. The proportion of antimony transferred into these products does not exceed 40%, and the rest is removed with slag flotation treatment tailings. With a relatively low antimony content in blister copper its electrolysis sludge contains up to 15% Sb. Dust and anode sludge are considered as a source of antimony production.



Use of Thiourea Leaching During Gold-Containing Dump Treatment
摘要
In Tadzhikistan the volume of gold-containing waste converted to gold is 18 tons. This waste is products of amalgamation and cyaniding processes., and with respect to end component content they may be classified as a very rich type of raw material since they contain 1.7–8.5 g/ton of gold, whereas the average gold content in ores extracted for processing in one of the richest deposits of the republic, i.e., Tarror, comprises 2.4 g/ton. In addition, treatment of these dumps does not require crushing and refining since they have adequate coarseness of a finished class. In view of this the research object is goldcontaining waste of Tarror ore and a number of other adjacent deposits that have been accumulated over a long time. Results are provided for the raw material substance composition of the test raw material and the possibilities of using thiourea leaching for processing them. The main process parameters are optimized and the degree of gold extraction at the level of 80% is demonstrated.
A fundamental production scheme is presented for processing dumps, including the following operations: preliminary acid treatment; sorption thiourea leaching; desorption; reactivation; electrolysis; melting.



Study of the Effect of Vibration Treatment of Porous Sintered Workpiece Treatment on Structure and Properties of Hot-Forged Powder Object Surface Layer
摘要
A number of combine-harvester components are produced by mass production of hot-forged sintered powder blanks in the at “Rostsel’mash” plant. With the aim of improving the structure and properties of a component surface layer before hot forging sintered workpieces are subjected to vibration treatment with application of a lubricant coating. Component surface layer structure is studied and properties are determined. A reduction is established in material overall degree and local decarburization, and wear resistance is improved by a factor of 1.35–1.4.



Technology for Production of Monodisperse Spherical Granules
摘要
The conducted study shows the possibility of improving the technology for producing monodisperse spherical granules. By modifying the surface of a die, it becomes possible to utilize the technology when granulating ErNi alloy. A potential for using the regime of forced capillary jet breakup with satellite droplets to expand the size-based operating range of the granulators in the finely-dispersed region has been demonstrated. To improve the granular quality, the forced capillary breakup regime with an excitation wavelength of about λ = 4.5d should be used.



Development of a Method for the Visualization of the Process of Forming of Curved Profiles in the Software Used for the Numerical Analyses of the Roll Passes
摘要
We propose a method for the visualization of the process of bending in the developed computer-aided system aimed at the design of equipment and tools used in manufacturing of bent profiles. The necessity of development of a special program for the numerical analyses of the profiling equipment of the rolls of roll-bending units is demonstrated. We present the description of the conditions of working with the proposed software and its functionality and discuss the method for the numerical analyses of changes in the geometry of the blanks. The displacements of reference points of the blanks in the production of arbitrary profiles according to the chosen flow diagram is analyzed. We also present graphic results of the numerical analyses of the profiling equipment for an arbitrary profile illustrating the possibilities of the program.


