Continuous-cast Semifinished Products Research Articles

Modeling the Piercing of Semifinished Products in a Three-Roll Rotary Rolling Mill on a Hollow Mandrel

The piercing of a tubular semifinished product by a hollow mandrel in a three-roll rotary rolling mill is modeled on a computer in the software DEFORM 3D. An analysis of the results showed the advantages of using a hollow mandrel instead of the traditional solid mandrel when a continuous-cast semifinished product is being pierced. Use of the hollow mandrel can alleviate variations in the thickness of the wall of the resulting hollow semifinished products.

Use of a Round Continuous-Cast Billet for the Production of Rolled Sections

Different methods of making rolled sections are analyzed along with the advantages and disadvantages of rolling sections from round and square continuous-cast billets. A literature search is made to find studies concerning the use of round continuous-cast semifinished products for making sections.

Production of Continuous-Cast Semifinished Products Made of Pipe Steels Alloyed with Rare-Earth Metals

The Severskii Pipe Plant has developed a technology for obtaining continuous-cast semifinished products made of pipe steels alloyed with cerium. Use of the technology makes it possible to homogeneously distribute the REM over the volume of the steel and give it satisfactory castability on continuous casters operating in the automatic regime. Up to 900 tons of liquid steel can be cast in a single series with the use of this technology.

Use of Finite-Element Modeling to Improve the Piercing Operation on a Piercing Mill

The authors evaluate the degree of agreement between results obtained from piercing continuous-cast semifinished products on a cross-rolling piercing mill and the indices of this process determined by finiteelement modeling. New piercing-mill equipment has been developed to make thin-walled hollows. Computer software is used to evaluate the optimality of the mill’s settings.

Introduction of a Level-2 Automated System as Part of the Reconstruction of a Walking-Beam Furnace in the Rail-Beam Shop

Engineers and scientists in Russia and abroad are giving a considerable amount of attention to improving the quality of the rails being made by metallurgical plants. Rolling 100-m-long rails requires proper preheating of the continuous-cast semifinished products with a minimal temperature gradient along and across the products. A heating operation of the requisite quality is assured by the use of a level-2 automation system to heat the metal in the furnace.

Trends in the technology and equipment for the production of copper tubes and bars from continuous-cast semifinished products in Russia

A brief analysis is performed of methods used for the continuous casting of semifinished products of copper and its alloys. The article describes the composition and characteristics of existing equipment and presents a universal complex for making hollow semifinished products. It also identifies trends in improving the equipment used for the production of nonferrous-metal semifinished products at micro- and mini-plants.

Selecting the diameter of a continuous-cast semifinished product for piercing shells at the seversky pipe plant

Results are presented from studies directed at reducing the damage done to hot-rolled tubes by internal scabs in the tube-rolling shop at the Seversky Pipe Plant. It is shown that it would be expedient to reduce the diameter of the continuous-cast semifinished product in order to alleviate surface defects and make the thickness of the tube wall more uniform in the transverse direction. An evaluation is made of the effect of adjusting the piercing mill and the reduction regimes on the formation of defects on the surface of tubes.

Method of calculating the optimum parameters for the air-mist cooling of a continuous-cast slab

This article examines the problem of determining the parameters for the air-mist cooling of a continuous-cast slab semifinished product. A method is proposed for solving this problem, the method being based on mathematical modeling of the temperature field of the slab. A criterion is formulated for optimizing the process of air-mist cooling and algorithms are developed to solve the given problem for an existing database of nozzle parameters.

Criteria of the quality of the temperature field of a continuous-cast ingot

This article examines different numerical characteristics of the temperature field of a continuous-cast semifinished product and examines their sensitivity to parameters of the casting operation. A method is proposed for evaluating the thermal state of ingots. The method can be used both at the design stage and in the course of operation of a continuous caster’s automated control system.

Choosing the shape and dimensions of punches for the operation of piercing on a press

Computer modeling and physical modeling are used to develop a method for choosing the shape and dimensions of a piercing tool based on the engineering problems that need to be solved. Results are given from use of the method to choose the shape and dimensions of tools in relation to the piercing force, the stability of the punches, the flow of metal into a hollow punch, and the removal of defects from continuous-cast semifinished products.

Selecting regimes for the delivery of slag-forming mixtures and oscillation of the molds on continuous casters

This article examines slag-forming mixture (SFM) feed regimes that provide for effective lubrication in continuous-caster molds and reduce the stresses in the skin of the continuous-cast semifinished product. It is shown that use of the mold oscillation regimes developed by the KORAD Corporation solves these problems and ensures dynamic balancing of the substantial loads that act on the structural elements of the caster during the vibration of massive molds.

Analysis of the formation of the solidifying skin of a round continuous-cast semifinished product inside the sleeve of the mold

The institute VNIIMETMASh has designed a new sleeve named VM-sinus for the continuous casting of round semifinished products. The working cavity of the sleeve is designed so as to ensure that it comes into intimate contact with the skin of the solidifying ingot both along the sleeve and about the perimeter of its cross section. Use of the sleeve has made it possible to produce commercial-sized batches of round semifinished products having the required geometric parameters.

Development of a theory of the strength of continuous-cast semifinished products made of peritectic low-alloy steel

A mathematical model is presented to describe the thermal stress state of the solidifying skin of the ingot during the continuous casting of peritectic low-carbon steel. A theoretical analysis performed with the use of the proposed model revealed that the magnitude of the tensile stresses in the ingot skin is significantly affected by the increased amount of shrinkage which occurs due to the δ→γ phase transformation. This effect is particularly strong during the intensive heat exchange that takes place near the top edge of the mold. The calculated thermal stresses in the skin are 1.5–2 times greater than the ultimate strength of the steel at temperatures close to the alloy’s solidus, which accounts for the high probability of rupture of the skin.

Technical solutions for controlling flows of melts in the tundishes of continuous casters

A relationship is established between the rate of eddy formation in tundishes, the velocity of the melt entering the tundish, and the degree of contamination of the continuous-cast semifinished product by nonmetallic inclusions. New hydrostabilizing and eddy-damping devices are proposed for use and their effects on the parameters of the casting operation and the quality of the cast metal are determined.

New method for cooling slabs in the secondary cooling zone of continuous casters that allows computer control of the slab crystallization process

A new contact-type method is proposed for controlling the cooling of continuous-cast semifinished products in the secondary cooling zone of continuous casters. The method employs water-cooled rollers and a system that controls the flow of coolant water. The method makes it possible to directly measure the removal of heat from the product, and it is based on a series of numerical-analytical models and highly precise algorithms. It is shown that it is possible to computerize control of the quality of cast slabs on the basis of real-time monitoring of the shape of the liquid crater and regulation of the slab’s macrostructure in each section.

Improving the technology for the tundish refining of steel in order to elevate the quality of continuous-cast semifinished products and rolled plates

An integrated technology has been developed for obtaining continuous-cast slabs to be used in rolling plates for critical applications. Special filtration elements are installed in partitions inside the tundish to reduce the content of nonmetallic inclusions in the continuous-cast semifinished product. A channeled ceramic lance for injecting the steel with argon has been developed and installed in the bottom of tundishes to remove nonmetallic inclusions 20 μm or smaller. Metallographic studies confirm the effectiveness of the new technology for obtaining plates of high-strength steels.

Modernization of the mold suspension system of continuous casters

This article presents a low-cost method of modernizing continuous-casting machines through improvement of the suspension of the mold. The replacement of lever-and-hinge type suspensions reduces or eliminates gaps in the unit and thus helps improve the surface quality of the continuous-cast semifinished product.

Improving a system for the secondary cooling of continuous-cast semifinished products on the basis of information on the actual thermal state of the ingot

A new system is proposed for controlling the secondary cooling of continuous-cast semifinished products. The system’s operation is based on the use of data on the actual thermal state of the ingot. These data are obtained by mathematical modeling and the use of a measurement complex that was designed as part of the system.

Effect of dendritic segregation in the continuous-cast semifinished product on the formation of the stucture of high-carbon-steel wire rod

This article examines the hereditary effect of microscopic dendritic segregation in the continuous-cast semifinished product on the structure (the presence of segregation-related striae and martensitic sections and their distribution over the cross section) of wire rod made of high-carbon steel. To improve the quality indices of wire rod, the casting technology should be stabilized by adding equipment for stopper-assisted pouring, fully protecting the stream with submersible refractory tubes, using modern mold-oscillation mechanisms (such as lever-type mechanisms), using parabolic molds that speed up crystallization of the CCS, and employing other measures. Maximum use should be made of heat treatment of the CCSs and rolled products, one of the goals here being to increase the degree of homogenization of the cast structure and rolled product and/or residues of that structure. This can often be achieved through longer heating of the CCS in walking-beam furnaces prior to the rolling operation.

Growth of the production of rails from continuous-cast semifinished products of electrical steel

Since 2001, the Novokuznetsk Metallurgical Combine has produced 3.0 million tons of R65 railroad rails of continuous-cast steel made in electric furnaces. The combine has significantly improved all the most important quality indices of the steel during this period, and the service life of the rails has increased from 0.5·109 to (0.8–1)·109 tons gross. The combine has mastered the production of rails with superior cold resistance and rails suited of use in high-speed rail systems. It is beginning production of rails with a bainitic structure and rails made of hypereutectoid steels. All these results have been obtained through the construction of new production facilities and modernization of the combine’s existing equipment. Plans for future rail production include extensive reconstruction of the heat-treatment section of the rail-beam shop and reconstruction of the machine-tool bay, the latter involving replacement of part of the equipment. Arc steelmaking furnace No. 1 and two continuous casters will be rebuilt in the electric steelmaking shop. The ultimate goal is to increase the durability and reliability of the rails so as to put them on par with the best rails in the world.