Regulating the macrostructure of continuous-cast billet

The macrostructure of 10, 20, 09Γ2C, and дб steel billet (diameter 150 and 220 mm) is investigated. Regardless of the casting parameters and grade of steel, the metal in the continuous-cast billet studied contains sections distributed randomly over the length that are characterized by impermissible central porosity in tests. The nonuniform distribution of this defect over the length of the billet is due to unstable solidification of the central zone and is not eliminated in continuous casting of the steel. The research permits the adoption of a new edition of Technical Specifications TU 14-159-324-2012 for continuous-cast billet, with requirements on the extent of the central porosity.     

Improving the cross section of continuous-cast billet

The introduction of new billet configurations ensuring high quality on initial formation in the mold is considered. These configurations also promote temperature and deformation conditions that stabilize the quality of the billet and subsequent rolled product.     

Defect healing in the axial zone of continuous-cast billet

Minimization of the metal consumption in components imposes ever-increasing structural requirements on steel. Accordingly, it is important to study the behavior of structural defects in continuous-cast billet (shrinkage pores, gas bubbles, axial porosity) during deformation. The use of laminar physical models to study the pressure treatment of metals is further developed in the present work. The influence of the strain on defect healing may be assessed by using laminar models together with defect application to the surface of layer n and the analysis of information regarding its distortion. The proposed method is applied to the deformation of continuous- cast bar billet in the first three rectangular grooves of the reduction cell in the 500/370 linear rolling mill at PAO Donetskii Metalloprokatnyi Zavod. On the basis of the experimental data, the existing healing mechanism for axial metal defects may be refined in terms of the total extension and the applied deforming forces.     

Production of hollow continuous-cast billet for seamless pipe

A promising method for producing more competitive seamless pipe on the basis of hollow continuous-cast billet is considered. The main difference between the new and standard methods is the design of the equipment.     

Macrostructure of hot-pressed boiler pipe made from undeformed continuous-cast billet

The macrocrystalline structure of metal in hot-pressed boiler pipe made from undeformed continuous billet is studied. The relation between the macrostructure of the metal and the operational reliability is determined. It proves expedient to monitor the steel macrostructure in thick-walled hot-pressed boiler pipe made from undeformed continuous billet, searching for residues of cast structure.     

Defects and thermal hardening of reinforcement rolled from continuous-cast billet

Defects of carbon and low-carbon steel reinforcement of periodic profile are investigated. Optimal heat-treatment conditions for reinforcement used in Kazakhstan are investigated in laboratory tests.     

Production of 180 × 180 mm continuous-cast billet from high-carbon steel

The introduction of the continuous casting of high-carbon steel into 180 × 180 mm billet is described. Measures are developed to increase the production series in the intermediate ladle from 3.5 to 10 melts. The basic factors that affect the development of microstructural defects—central porosity, as well as liquation bands and cracks extending over the cross section—are identified. The technology is corrected so as to hinder the development of such defects.     

Centering of continuous-cast billet prior to piercing at OAO Severskii Trubnyi Zavod

Attention focuses on how the centering of continuous-cast billet prior to piercing affects the geometry of thin- and thick-walled sleeves at OAO Severskii Trubnyi Zavod. The influence of the depth and shape of the rear centering socket on the variation in wall thickness at the rear of the sleeve is studied.     

Reducing the central porosity of continuous-cast billet by modification of the solidification process

The quality of continuous-cast billet is considered. Means of improving billet solidification are developed, with the pulsed injection of inert gas into the metal in the mold and shear-enhanced mild compression of the billet in the secondary-cooling zone of the continuous-casting machine. These measures are found to shrink the columnar-crystal zone and reduce the central porosity.