Method and device for determining uniform ductility of hi-grade steel pipeline steel pipe

Abstract

The invention discloses a method for determining uniform ductility of a hi-grade steel pipeline steel pipe, and relates to the technology of pipeline steel materials. The method comprises the following steps of: picking a tensile sample on a pipe body of a hi-grade pipeline, and obtaining an engineering stress-engineering stress curve through a tensile test; taking two percent points toward the stress positive and negative directions near points corresponding the biggest press on the engineering stress-engineering stress curve to fit a data range; and fitting the engineering stress-engineering stress curve in the data range, and obtaining the uniform ductility. The invention also discloses a device for determining the uniform ductility of the hi-grade steel pipeline steel pipe. The method for determining the uniform ductility of the hi-grade steel pipeline steel pipe has the advantages that the engineering stress-engineering stress curve of the tensile test is fitted, the mathematical expression of the curve is obtained, the real uniformity ductility numerical value of the material is determined on the foundation, the deformation performance of the steel pipe is objectively judged, and an erroneous judgment is avoided.

Description

technical field [0001] The invention relates to pipeline steel material technology, in particular to a method and device for determining the uniform elongation of high-grade pipeline steel pipes. Background technique [0002] In general, pipeline failures are load-controlled failures using design criteria based on stress limits. However, for pipelines laid in harsh environments such as earthquakes, debris flows, landslides and other geological disasters, tundra and seabeds, the magnitude of the load cannot be controlled, and the deformation will only stop after the displacement reaches a certain level. In this case the load is controlled by displacement or strain. In this case, simply using the traditional stress limit criterion to design can no longer guarantee the safety of the pipeline, and the strain limit criterion must be adopted, that is, the design strain of the pipeline must be less than the allowable strain of the pipeline. The allowable strain of the pipeline is...

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