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.     

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.     

Dark scabs in corrosion-resistant titanium steel after ladle treatment

Defects in the form of dark scabs detected by ultrasonic monitoring are studied in the macrostructure of corrosion-resistant titanium steel after ladle treatment. The type and morphology of the inclusions in the defect are studied, and their origin is analyzed. The role of exogenous and endogenous inclusions in the dark scab is discussed.     

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.     

Controlled rolling of high-strength microalloyed pipe steel on a 5000 thick-sheet mill

Models are developed to describe and predict the geometric and temperature conditions of thick-sheet rolling at different stages (with determination of the billet parameters, its chemical composition, and also the conditions of heating, rough and final rolling, and accelerated cooling). On that basis, effective production conditions for pipe blanks of strength classes K60 and X80 are formulated, so as to ensure the required structural state and specified mechanical properties of the blank.     

Hot plasticity of microalloyed pipe steel in continuous casting and hot rolling

The influence of continuous casting and hot rolling (on a broad-strip 2000 mill) on the hot plasticity of microalloyed pipe steel (strength category X42) is investigated. A Gleeble 3800 system is used for physical modeling of the hot plastic deformation. The temperature intervals corresponding to loss of plasticity are determined in different conditions of slab cooling during continuous casting. In subsequent rolling, the loss of plasticity typical of cooling in the continuous-casting machine is not seen, and the steel is highly plastic.     

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.     

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.