Research On Recrystallization Behavior Of X80 Pipeline In Hot Transmutation

Recent research of pipelines has shown a trend which towards higher operation pressure with greater wall, thickness and higher strength pipeline. And X80 grade acicular ferrite pipeline steel with the fine property will be extensively applied in the future. Therefore, there will be a very important significance to research the phase changing and microstrcture control of X80 pipeline by hot simulation technology.This paper apply controlled rolling and controlled cooling technology to the production of micro-alloyed pipeline steel of X80 high grade pipeline by gleeble-1500D hot simulation technology. To research the refinement of grain size and phase changing of X80 pipeline by single-pass, double-pass, Multi-pass hot simulation technology. Experimental processes and results are as follows:Use the single-pass compression experiments on X80 pipeline steel in hot deformation in the process of dynamic recovery and dynamic recrystallization softening behavior. Come to true stress-strain curves and analyze its recrystallization behavior. Find out critical strain for dynamic re-crystallization based on single pass stress-strain curves of X80 pipeline steel;Use double-pass compression experiment to study the softening behavior between different pass interval time of X80 pipeline steel in hot rolling. Come to stress-strain curves in different pass interval time.Find out the austenite re-crystallization zone partially re-crystallization zone and no re-crystallization zone;Multi-pass compression experiment by Gleeble-1500D thermo-mechanical simulator.The control rolling and control rolling technology are used to X80 pipe-line . We can refine grain size by increasing the pass deformation,controling the finishing rolling temperature,increase the cooling rate and control other deformation condition;The ultra-fine austenite grain size can be obtained by dynamic re-crystallization. we can optimize the rolling technology by controlling the static re-crystallization to avoid uneven grain size. Large strain accumulation is basic condition for exceeding of critical strain for dynamic re-crystallization in finishing rolling pass.