Publication Details

Kostryzhev, A. G., Strangwood, M. & Davis, C. L. (2010). Mechanical property development during UOE forming of large diameter pipeline steels. Materials and Manufacturing Processes, 25 (1-3), 41-47.


Mechanical properties of large diameter welded steel pipes depend on the thermomechanically controlled rolled (TMCR) plate microstructure and UOE pipe-forming cold deformation sequence. Strength from plate to pipe may increase (work-hardening) or decrease (the Bauschinger effect). Bauschinger effect parameters depend on steel composition and plate processing history. The present study is examining two pipeline grades: X60 (Nb-alloyed) and X65 (Nb- and V-alloyed). Mechanical properties are determined by grain refinement, solid solution, precipitation strengthening mechanisms, and work-hardening (work-softening). The reverse deformation yield drop increases with an increase in the precipitate particle volume fraction and pre-strain. Annealing, leading to a decrease in the dislocation density, reduces the yield drop. The Bauschinger parameters are being quantitatively related to the particle type, size, and volume fraction, and the dislocation density.



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