Improving the production of pipe steel

Melts of pipe steel (strength class K52) obtained at the casting and rolling complex of AO OMK (a branch of AO OMK-Stal’) are analyzed. The initial data correspond to a set of 30 melts. The production system includes batch preparation, steel production in an arc furnace, treatment in a ladle–furnace unit, vacuum treatment (with microalloying and modification), hot rolling, and cutting of the rolled steel into sheet and strip. The basic factors affecting steel quality are identified. The rejection of the steel produced is mainly due to brittle and undeformable nonmetallic silicate inclusions. Changes in the process so as to reduce the content of nonmetallic silicate inclusions are recommended.     

Improving the quality of rolled pipe steel products by minimizing the bending of the ends of plates

The causes of the vertical bending of the front ends of plates during hot rolling are revealed. A finite-element mathematical model is developed to describe the state of stress of the metal in an asymmetric deformation zone with allowance for solving a temperature problem, and the model is adapted to the conditions of the 5000 rolling mill in OAO MMK. It is found that, in rolling with mismatched work roll speeds, the direction of bending of the front strip end is determined by the strip thickness and the deformation zone shape. The main cause of the bending of the front plate end at the stage of finishing stage of rolling is shown to be the difference between the roller bed level and the rolling line. New asymmetric deformation regimes are developed with allowance for the effect of the deformation zone shape on the direction of bending of the front strip end. The developed technological regimes of asymmetric rolling make it possible to decrease the mill downtime because of the bending of the breakdown bar ends and to reduce the metal volume rejected because of violated temperature regimes of the thermomechanical treatment of plates.     

高品质管线钢钙处理夹杂物变性研究

通过对国内某钢厂生产的B(PSL1)高品质石油管线钢钙处理前后钢中夹杂物类型的变化研究,从热力学上分析了钢中Al2O3夹杂的变性机理及夹杂物中CaS含量较高的原因.研究结果表明现有工艺条件下,喂入的硅钙线可以将Al2O3夹杂变性为炼钢温度下呈液态的12CaO·7Al2O3夹杂.同时,也可以将MnS完全变性为CaS,但钢中有大量单独的CaS生成.     

Improving the roller shaping of large-diameter pipe from strip

Current geometric requirements on pipe—especially thin-walled pipe for gas pipelines—set strict limits on the deviation of the cross section in shaping. A special control algorithm for the drives in the sheetbending machine minimizes local geometric errors in the cross section during the roller shaping of largediameter pipe from strip. Analysis of the nonuniformity in deformation permits the formulation of a cyclic operating sequence for the drives. Experiments confirm its effectiveness. On the basis of this research, automatic control of the drives in the sheet-bending machine is possible.     

开展焦炭质量攻关提高焦炭实物质量

通过加强炼焦基础管理、优化工艺操作、严格检验把关、提高服务质量等一系列质量攻关工作的开展,有效地提高了焦炭实物质量,保障了炼铁、炼钢生产的顺利进行。     

Improving the manufacture of corrosion-resistant steel pipe for power plants

The quality of corrosion-resistant steel pipe is critical to energy conservation. Prospective requirements on such pipe call for a fundamental change in the manufacturing technology, including higher internal-surface quality, limited residual stress, and minimum chloride ions at the surface.     

Improving the production of electrowelded straight-seam pipe. Part 2

For 12 years, specialists from Baikov Institute of Metallurgy and Materials Science and PAO Severstal’ have been focused on introducing and improving production technology for smalland medium-diameter welded straight-seam pipe at PAO Severstal’. The results are summarized in the present work. The adjustment of the supporting and welding system is discussed. Welding by high-frequency currents permits more efficient edge heating of the pipe blanks and the production of high-quality weld seams.