Structure Of Wire Rod Research Articles

DETERMINATION OF RATIONAL PARAMETERS OF COOLING OF PEARLITIC GRADE STEELS WIRE ROD IN THE LINE OF WIRE ROLLING MILL

Wire rod from pearlitic steels and carbon content of 0.7-0.9 % is attributed to the responsible range of metal products, so its quality indicators are subject to very strict regulatory requirements. The results of research indicate that in industrial conditions there are all the necessary prerequisites for the effective impact of deformation-heat treatment on the processes of structure formation and ensure a more uniform distribution of structural components in the cross section of the wire rod. Increasing the average mass temperature increases the stability of austenite before the start of continuous cooling, and together with the lack of water cooling provides the formation of a more dispersed and homogeneous structure of wire rod of pearlitic grade steel.

ПРО МОЖЛИВІСТЬ ПРОГНОЗУВАННЯ МЕХАНІЧНИХ ВЛАСТИВОСТЕЙ ХОЛОДНОДЕФОРМОВАНИХ МЕТАЛОВИРОБІВ ЗІ СТАЛЕЙ ПЕРЛІТНОГО КЛАСУ

In accordance with the latest global trends and modern needs of hardware factories, the demand for wire rod made of pearlitic steels has significantly increased, which can undergo cold plastic deformation with large degrees of reduction and is intended for the manufacture of various commercial products (cold-worked reinforcement, reinforcing ropes, spring wire, steel cord, wire for high pressure hoses, construction fiber, etc.). The most promising direction for increasing the strength class of hot-rolled steels is strain hardening during cold plastic deformation. The structure of cold-worked steels has a more uniform distribution over the cross-section, in contrast to thermally hardened ones, which in the latter case are characterized by annular structural zones formed due to different mechanisms of austenite decomposition. In a number of cases, structural heterogeneity causes instability of the mechanical properties of rolled steel, therefore, there is currently no alternative way to strain hardening. The manufacture of high-strength cold-worked metal products is a complex process and depends on the quality of the wire rod. If the cold-worked hardware does not meet the requirements of the normative documentation for the strength class, then it is no longer possible to ensure the correction of this defect using heat treatment. In this regard, scientific and practical interest has arisen to determine the possibility of creating a method for predictive determination of the mechanical properties of cold-deformed metal products made of pearlitic steels. The features of the influence of cold plastic deformation by on the formation of the strength class of pearlite grade steels with a carbon content of 0.7…0.9 % are considered It is established that the temporary resistance to fracture, at the known parameters of structure and carbon content, lends itself well to mathematical calculations and allows to create predictive models. According to the results of the research, a computer program was created that allows to automatically calculate the energy parameters of drawing and determine the tensile strength of the wire after depending on the total relative compression, parameters of the structure of wire rod and the carbon content in the steel.

Влияние металлургических факторов и термической обработки на структуру катанки под металлокорд

Влияние металлургических факторов и термической обработки на структуру катанки под металлокорд

Microstructure and Properties of Al-Mg-Si Wire-Rod Subjected to Continuous Heat Treatment

Among multiple applications 6XXX-series aluminum alloys are widely used as electrical conductor for overhead power lines. For that application Al-Mg-Si alloys are produced mainly in the form of wire rod in the continuous casting and rolling lines (CCR). There is many technological routes possible to transform the Al-Mg-Si wire-rod into precipitation hardened, ready to use Al-Mg-Si wires. One of these routes involves using the heat of continuous casting and rolling process to artificial ageing of wire-rod, which is motivated by ecological premise. In the current paper the results of continuous heat treatment of the wire-rod within the CCR line (involving quenching of the alloy to artificial ageing temperature) on the microstructure and properties has been examined. It was shown the structure of wire rod formed in such process is very irregular. TEM investigations has shown that many heterogeneous particles are present and the arrangement of the β main hardening phase is very inhomogeneous with wide precipitate free zones occurred. However this type of microstructure has a positive effect on electrical properties of the material in question, which is important taking into consideration application of the alloy.

Fine microstructure of wire rods manufactured from Sv-08G2S high-plasticity steel

This paper presents the results of transmission-electron-microscope and scanning-electron-microscope studies of the fine structure of wire rod made from Sv-08G2S silicon-manganese welding steel, including electron microscope images used to identify the structural components of the wire-rod metal and determine the dislocation density. The wire-rod microstructure was compared against that obtained when a new, optimized process was developed for heat-treatment of the wire rod in a Stelmor line. We show that the wire rod has the highest ductility when the production flow includes long-term holding of the wire-rod coils under quasi-isothermal conditions (under insulated hoods with a cooling rate 0.2-0.3°C/sec) in such a way as to minimize the number of bainite-martensite areas when the structureless martensite (hardenite) content does not exceed 5%. The resulting process and optimized microstructure enabled us to achieve a relative deformation of 98% when direct-drawing wire rod from Sv-08G2S alloy steel.

Production of high-quality wire rod

Currently, world wire-rod output exceeds 50 million t/yr, which is ~10% of the total rolled-metal output. To produce more competitive wire rod and hence increase sales, manufacturers need to better satisfy the requirements on the mechanical properties and structure of the steel, the dimensional precision, the bale size, and other characteristics. In the 1970s, the finishing groups of wire mills began to be replaced with finishing cell modules and two-stage cooling lines. In the next 20 years, the rolling rate of wire rod increased from 35 to 120 m/s, the bale mass reached 2.0‐2.5 t, and the dimensional accuracy of the wire rod increased from ± 0.5 mm to ± 0.10‐ 0.15 mm. Besides the structure of the wire rod, the mechanical properties and their uniform distribution over the bale length improved. The range of final products expanded [1‐3]. The mass-production of wire rod of 5.5-mm diameter was organized, without loss of productivity of the mills. There was an increase in the output of wire rod made from high-alloy and special steel and alloys and from continuous-cast billet. Reequipment of wire mills consumed considerable capital expenditure, especially in radical reconstruction. However, the investment was recouped in full, thanks to the improved quality and broader range of the wire rod. As a rule, after 10‐15 years of operation, mills are partially modernized, with the installation of up-todate equipment. Reequipment began in the Soviet Union in 1979, when a new 150 mill wire mill was introduced at Beloretsk Metallurgical Works (BMW). The 250-2 mill at Cherepovets Metallurgical Works was them reconstructed; mini mills were built in Moldavia and Belorussia with modern 320/150 small-rod and wire mills; and 150 wire mills went into operation at Makeevsk Metallurgical Plant (MMP), as well as 150 and 250/150 mills at Krivorozhstal works. In collaboration with plant specialists, researchers at the Institute of Ferrous Metallurgy (IFM) improved the design technology for a series of wire mills. As a result, high-quality wire rod went into production, including rod made from different grades of steel. For example, the rolling rate was increased at the BMW 150 mill, and metal consumption was reduced, with improvement in overall performance. In addition, rolling from lowertemperature billet reduced the metal losses on account of scale and also the gas consumption [4]. The water-cooling system for the wire rod was redesigned, and two-stage cooling was introduced, with improvement in the structure and properties of carbonand alloy-steel wire rod. This permitted simplification of the subsequent treatment and reduced metalware production costs [4‐6]. After a number of years, the BMW 150 mill and the 320/150 mill at Belorussian Metallurgical Plant (BMP) were reconstructed. At BMW, high-speed units with refined gear ratios from the electric drive to the rollers were introduced. The line for cooling wire rod in coils was reconstructed on the basis of research data from IFM, the All-Russian Scientific-Research Institute of Metallurgical Technology (ASIMT), and BMW; cooling by high-speed air fluxes was introduced. At BMP, the small-bar and wire mill was divided into a 320 small-bar mill and a 150 wire mill, with integration of the primary and secondary equipment [2]. The reconstruction costs for the BMP 320/150 mill (with the participation of foreign firms) were recouped within 2‐3 years of operation. Thanks to improvement in wire rod quality and performance, the manufacturing technology for metal cord was improved, and cord exports increased. Where necessary, high-speed air fluxes were used in cooling coils of high-carbon wire rod; this expanded the range of both 150 mills and improved the metal structure. The wire-rod output for the production of high-strength metal cord increased; the quality of cable and high-carbon wire rod for the manufacture of high-strength reinforcing wire was improved, thereby eliminating the need for one patenting operation in metalware production. The production of high-quality wire rod for cold bulk stamping increased; the structure and mechanical properties of the metal became more uniform over the length of the bales. At IFM, a mathematical model of continuous rolling in the finishing modules with a common cell drive has been developed. It may be used to determine and regulate the longitudinal stress in the steel between the cells, in the baseline (design) mode, as well as the rolling

Inverse magnetostrictive effect and electromagnetic non-destructive testing methods

The influences of mechanical stresses on magnetic properties are investigated. A qualitative and quantitative description of the reversible and irreversible components of the magnetostrictive effect in iron and carbon steels is presented. Applications of the effect in a new method for analysis of stress waves in mechanically stressed ferromagnetic metals, and also in an alternative strategy for enhancement of the signal-to-noise ratio of eddy current testing of tubes, wires and rods in mechanized lines are described, as is a non-destructive method for evaluation of the martensite content in the structure of wire rod.