Elastoplastic shaping of metal in an edge-bending press in the manufacture of large-diameter pipe

An analytical method is outlined for calculating the edge-bending parameters of thick sheet: the size and shape of the thick sheet in shaping and after shaping on an edge-bending press; the spring-action coefficient; and the residual curvature of the edge. At all stages of the process, the model of an elastoplastic medium is considered. The results may be used in developing a production technology for large-diameter steel pipe used in oil pipelines.     

Expansion of large-diameter welded pipe

The expansion of large-diameter welded pipe is modeled by the finite-element method. The dependence of the oval distortion of the pipe on that of the pipe blank is studied. The equivalent stress is changed by the first expansion step.     

The Bauschinger effect and the formation of microalloyed-steel properties in pipe manufacture

The Bauschinger effect is investigated on samples of microalloyed pipe steel. Tests are conducted with one and several extension-compression cycles on a Gleeble-3800 system, at room temperature and elevated temperatures. The influence of temperature on the final sheet properties is considered in conditions of small alternating deformation, so as to simulate the straightening of hot-rolled sheet. The successive influence of each cycle on the final properties of the metal is demonstrated. The strength of the final strip may be modified by 150 MPa, depending on the selected straightening temperature.     

Shaping of blank in large-diameter pipe production

The three most promising production methods for large-diameter pipe are considered. These methods are employed at Russian plants. Each one has advantages and disadvantages. Detailed study is required to improve product quality.     

Production of high-weldability steel for large-diameter pipe

The use of controlled rolling for coiled steels of type 05G1B — which are distinguished by their low carbon content (0.04–07%), economical alloying (Cr, Ni, Cu), and microalloying with niobium — ensures formation of the requisite set of characteristics in the coiled product: a combination of high strength with good weldability and cold resistance. This is achieved through the formation of a ferritic-bainitic structure with fine ferrite grains and dispersion-hardening of the steel by niobium carbonitrides. New high-weldability steel 05G1B can be recommended for use in the production of electric-welded large-diameter gas-line pipe of strength class K56. __________ Translated from Metallurg, No. 2, pp. 36–40, February, 2006.     

Simulation of the shaping of blanks for large-diameter pipe

An analytical method is outlined for calculating the bending parameters of thick sheet (thickness up to 40 mm) used in pipe production: the size and shape of the punch-blank contact zone; the elasticity coefficient of the blank and its residual surface curvature; the maximum force of the punch at different stages of stepwise shaping on a press. At all stages of the process, the model of an elastoplastic medium is employed. The results may be used in developing production technologies for large-diameter steel pipe used in pipelines.     

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.     

Improved shaping of the blank for welded large-diameter pipe

A new method of shaping single-seam welded large-diameter pipe is proposed. This method employs an additional deforming tool.     

Shaping of thick sheet in the production of welded large-diameter pipe

An analytical method is proposed for calculating the shaping parameters of thick sheet in the production of large-diameter pipe. This method is considered in several stages: formulation of a geometric model of the blank and the tool; numerical calculations; selection of the algorithm; and analysis of the results. Comparison of calculated and experimental shaping parameters for sheet used in the production of different types of large-diameter pipe reveals good agreement. The proposed method is recommended for calculating the shaping parameters in the production of large-diameter pipe and the setup so as to minimize the defects due to the geometry of the press.     

Shaping of sheet to produce large-diameter welded pipe

The quality of welded pipe (diameter 508–1420 mm; wall thickness 8–48 mm) of strength class up to K80 (X100) is investigated. Plastic shaping is simulated, with quantitative estimation of the stress–strain state of thick-walled pipe blanks in TESA 1420 presses during edge bending and stepwise shaping. The corresponding computer program permits calculation of the setup of the equipment and determination of the geometric parameters of the pipe blank specified in the standards. Theoretical results are presented for a range of large-diameter pipe produced on the TESA 1420 system.     

钢坯组织性能控制对轧制成品的影响

文章就钢坯组织形态对成品性能的影响，钢坯的加热和冷却同组织结构的关系作了分析，并对提高成品质量提出了建议．     

Failure of large-diameter steel pipe with rolling scabs

Russian pipelines employ large-diameter pipe of straight-seam, two-seam, and spiral-seam type (diameter up to 1420 mm, API strength class up to K65). The newest developments in the production of large-diameter (1020, 1220, and 1420 mm) straight-seam welded pipe (strength classes K38–K65 and X42–X80, wall thickness up to 52 mm, length up to 18 mm, and working pressure up to 22.15 MPa) is stepwise press shaping (the JCOE process), proposed by SMS Meer (Germany). The SMS Meer technology is widely used at Russian pipe plants (AO Vyksunskii Metallurgicheskii Zavod, AO Izhorskii Trubnyi Zavod, PAO Chelyabinskii Truboprokatnyi Zavod) and also plants in Russia, China, and India. However, the accident statistics for Russian pipelines show that stress corrosion of the pipe wall mainly occurs in pipelines of large diameter (700–1420 mm). More than 80% of pipeline failures associated with stress corrosion occur in pipelines of diameter 1020–1420 mm. Corrosion cracking of pipe walls may be attributed to three main factors: (1) poor steel quality and pipe defects in manufacturing (such as high residual stress, microcracks and micropeeling of the metal after shaping of the pipe blank, corrugation, scratches, scabs from the rolling process, and imperfections of the weld seams); (2) the presence of a corrosive medium and its access to the metal surface; (3) multicyclic fatigue and failure of the metal on account of pulsation of the working pressure within the pipe and hydraulic shocks. In Russian oil pipelines, failures due to production defects and assembly and installation problems are twice as frequent as in the United States and Europe. Therefore, careful study of pipeline failure due to production flaws is of great importance. In the present work, a mathematical approach is proposed to determining the critical pressure in the pipe at which elastoplastic failure of the pipe will occur at rolling scabs accompanied by a scratch on the pipe’s outer surface. The results may be used in failure diagnostics of large-and medium-diameter steel pipe for major delivery pipelines and transfer pipelines.