April 2015, № 4 (179)

Gorbachev C.B., Fot A.P., Shchipachev A.M., Lutfullin R.Ya. INFLUENCE OF POST-WELD TREATMENT ON THE STRUCTURAL FEATURES OF WELDED JOINTS OF STEELS 20 AND 30KHGSATypical form of a limit condition of the vessels working under pressure is destruction or damage as result of development of a crack. The usual location of cracks are welded seams or their vicinities. Automatic welding under a gumboil layer is widely applied to production of the welded bottoms of the vessels working under pressure. Manual arc welding is applied mainly in the unions having short and faltering seams, seams of a difficult configuration. Decrease in mechanical and operational properties of welded connections is a consequence of structural changes. Welding tension also promotes acceleration of corrosion processes. The used methods of heat treatment of welded connections are long and power-intensive, don't provide uniform strength of a seam and the main metal. For achievement of structural uniformity and providing a combination of high durability and plasticity use of hot plastic deformation of welded seams in the temperature and high-speed modes of manifestation of effect of superplasticity of metals is represented perspective. In article the problem of decrease in structural imperfections of welded connections steel 20 and 30HGSA is solved. The method of the X-ray diffraction analysis investigated models of welded connections after different types of processing Is established that for welded connections from steel 20 all types of postwelding processing lead to decrease in microtension, for welded connections from steel 30HGSA after annealing and thermocyclic processing reduction of microtension isn't observed, and rolling by the heated rolls in the mode of superplasticity (joint venture) allows to reduce microtension. Novelty is use of postwelding deformation processing of welded connection by heated rolls (isothermal rolling) in the mode of superplastic deformation (ε = 20 %).Key words: superplastic deformation, residual tension, welded connections, oil and gas equipment.

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References:

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About this article

Authors: Gorbachev S.V., Fot A.P., Shchipachev A.M.

Year: 2015

Editor-in-chief

Sergey Aleksandrovich
MIROSHNIKOV

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