Production of new isotropic electrical steels at OAO NLMK

Specialists at OAO NLMK, in close collaboration with research institutes, have developed new grades of isotropic electrical steels and practical principles for their mass production, especially for use in high-efficiency magnetic cores. These include steels with low magnetic losses, high magnetic induction, and high magnetic permeability (high-permeability steel); semiprocessed rolled products from several alloying groups; and steel for high-speed stamping. The proposed technologies have no counterparts anywhere in the world and permit complete import substitution.     

Producing high-quality strip (thickness >16 mm) at the OAO MMK 2000 broad-strip mill

Improvement of relatively thick strip (16–20 mm) produced on the OAO MMK 2000 broad-strip mill is considered. Artificial neural networks may be used to optimize broad-strip hot rolling, so as to obtain the required mechanical properties of the strip produced. High surface quality of the strip may be ensured on the basis of finite-element models for predicting the behavior of surface defects on rolling and hence identifying effective rolling conditions.     

Simulation of the longitudinal thickness deviation of the steel strips hot rolled in the continuous group of a broad-strip mill

A model for the formation of longitudinal thickness deviation in hot-rolled strips as a function of the rolling parameters and an algorithm for optimizing the rolling conditions for the criterion of the minimum longitudinal thickness deviation are developed and implemented in the form of computer programs. This optimization is performed by the redistribution of percent reductions over the stands of the finishing group in a broad-strip hot-rolling mill. As a result of the application and industrial tests of the developed computer programs on a 2000 rolling mill, the longitudinal thickness deviation of hot-rolled strips is decreased by a factor of 1.87.     

Selecting mixtures for continuous casting of rail steel at OAO EVRAZ ZSMK

Two versions of TSK-K-20 mixture are selected for the casting of 300 × 340 mm rail-steel billet on a radial continuous-casting machine: TSK-K-20B1 and TSK-K-20B1m. Their chemical composition and thermophysical characteristics are investigated. The mixtures ensure the required surface quality of the billet and the rolled product; the life of the submersible nozzles is at least 20 h. At present, these mixtures are used instead of ShOS-1 mixture for continuous casting in the electrosmelting shop.     

Production of coiled pipe-steel sheet of improved reliability on the 2000 mill

A production technology for coiled sheet with improved operational reliability (low-temperature stability, corrosion resistance) is developed for the 2000 broad-strip hot-rolling mill. The steel sheet will be used in the production of oil and gas pipe.     

八钢连续棒材生产线生产弹簧扁钢工艺技术

通过设计孔型、制定加热工艺、轧制工艺,修改电气程序,实现弹簧扁钢在连续式棒材生产线的生产.     

GCr15轴承钢连铸冷却速率下凝固原位观察

GCr15轴承钢在连铸凝固过程中的组织生长与溶质偏析是碳化物液析的重要诱因,成为产品质量提升的关键.为此,针对国内某钢厂240 mm×240 mm GCr15轴承钢的连铸过程,选取方坯表面下方40、80和120 mm位置处的坯样为研究对象,首先建立二维凝固传热模型,结合红外测温试验,求解它们在糊状区的平均冷却速率,然后...     

Plasma hardening of cast-iron rollers for channel production on a 450 mill at OAO EVRAZ ZSMK

The microstructure and microhardness of the hardened surface layers of cast-iron rollers are investigated. Plasma hardening of the grooves in a 450 mill is proposed. Industrial tests show that this approach extends roller life.     

Analysis of various versions of the deoxidation of rail steel at OAO NTMK

The deoxidation of steel melted using various types of deoxidizers during out-of-furnace treatment is studied. The total oxygen and nitrogen content and the oxygen contents in the main types of oxide nonmetallic inclusions are determined by fractional gas analysis of steel samples taken from heats performed by various schedules. The main types of nonmetallic inclusions and their size distributions are found with qualitative and quantitative metallography. The oxygen content in the rail steel is minimal (5 ppm) when calcium carbide CaC₂ is introduced into the metal in tapping of a converter. When the metal is deoxidized using a steel wire filled with calcium or a steel wire filled with silicocalcium, the oxygen content in rail steel is ≈8 and ≈11 ppm, respectively. A comparison of various processes of rail steel deoxidation under the OAO NTMK conditions shows that the limitation of the aluminum content (no more than 30 ppm) or the use of a wire with a calcium or calcium carbide filler is more effective than the use of a wire filled with silicocalcium.