Quantitative measurement method for acicular ferrite of pipeline steel

Abstract

The invention relates to a quantitative measurement method for acicular ferrite of pipeline steel, which utilizes an electron backscattered diffraction (EBSD) assembled on a scanning electron microscope (SEM) to carry out quantitative measurement on the acicular ferrite of the pipeline steel and comprises the following steps: grinding the cross section of a pipeline steel sample into a metallographical polished surface; etching the polished surface with natal, eliminating surface stress and showing an acicular texture; utilizing a conductive adhesive to fix the prepared sample on an EBSD sample stage; controlling the sample stage to rotate for 70 degrees by utilizing the SEM; vacuumizing an electron microscope sample chamber; when the vacuum degree reaches the electron microscope operating requirements, applying operational high pressure to acquiring an image, and finding a typical viewing field; stretching the probe of the EBSD into the sample chamber, and acquiring EBSD pattern data; and carrying out statistical treatment on the EBSD pattern data to obtain the effective crystallite dimension of the acicular ferrite texture. The invention is applied to the quantitative measurement of the acicular ferrite texture with unsharp boundaries in the pipeline steel.

Description

technical field [0001] The invention relates to a method for measuring the microstructure of pipeline steel in the field of iron and steel material research, in particular to a scanning electron microscope using an electron backscattered diffraction device (electron backscattered diffraction, hereinafter referred to as EBSD) to detect acicular ferrite with inconspicuous boundaries in pipeline steel Quantitative measurement of effective grain size. Background technique [0002] Modern high-strength steel structure research shows that the important organizational unit in steel is the effective grain, that is, the organizational unit corresponding to the size of the cleavage facet in the electron microscope fracture analysis. Effective grain size has different concepts and meanings in different organizational structures. In ferrite-pearlite pipeline steel, polygonal ferrite corresponds to the cleavage facet, and the grain diameter of polygonal ferrite represents the effective ...

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Problems solved by technology

It should be pointed out that in the contents of these documents and patent reports, EBSD devices are used to conduct relevant research on various structural properties in steel (for example, in the patent published by Kawasaki Iron and Steel of Japan, only the acicular ferrite EBSD pattern Quality, fine structure, etc. and the relationship between process parameters have been studied), but none of them involve the method, step or key point of quantitatively measuring the effective grain size of acicular ferrite by using EBSD as described in this application

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