Study On Properties Control And Production Process Of X80 Pipeline Steel With Strain-based Design For Heavy Plate

With the extensive use of the pipelines,the using of the pipeline crossing the earthquake zone,tundra and marine areas occurs frequently.In order to satisfy the complex geological environment requirements,the pipeline with a higher elastic limit during the plastic deformation will be required.Therefore,strain-based design meets the requirement of the pipeline.In addition,based on the performance of the present pipeline steels,the property with large deformation resistance has been put forward,that is to say a kind of pipeline steel with a lower yield ratio,higher uniform elongation.In the production process,we found that it was particularly important to control the microstructure of the steel sheet,then the pipeline steel can obtain lower yield ratio and higher uniform elongation.This project mainly focus on the deformation capability of the pipeline with strain-based design,two aspects will be focused on,including meeting the requirements of a low yield strength and obtaining the designing microstructure.Taking full use of the fine grain strengthening,solid solution strengthening,dislocation strengthening,precipitation strengthening and other integrated strengthening mechanism will achieve the first goal,while for the second goal,the designing and production process controlling will be used to looking for industrial production process window,which would ensure that the performance requirements for the target pipe,steel plate industrial pipe,steel strain verify the applicability of the performance.Through continuous cooling condition analysis of low carbon and micro alloying designed composition steel plates,we can confirm the target tissue after the change of austenitic dynamic.By optimizing the heating technology and rolling technology parameters,we can attain smaller initial austenite grain size.Utilizing TMCP process to control cooling path of X80 pipeline with Strain-Based design,we can get a duplex organization of uniform refined Ferrite + Bainite.Ferrite,as soft ferrite phase in the organization,has a lower yield strength and higher uniform extension value.Bainite,as hard phase organization,has higher strength.rational Distribution of the volume fraction of Ferrite and Bainite can not only ensure high strength and high uniform elongation,but also get lower showed,so that X80 pipeline steel after rolling and piping can get good comprehensive performance to meet the design requirements of sustaining large deformation.In addition,developing proprietary strain on rolling region with X80 pipeline steel plates,controlled cooling and straightening model can achieve a stable batch production;The newly developed X80 pipeline steel has good strain properties,lower yield ratio and higher uniform elongation values,which will be adaptable for the third and fourth geological environment seismic zone,tundra and oceans.