Quantitative analysis method for volume content of each phase in QP steel

Abstract

The invention discloses a quantitative analysis method for the volume content of each phase in QP steel, which is characterized in that the volume content of ferrite in the QP steel can be obtained by subtracting the volume content of martensite of the QP steel obtained by a color metallographic method by 100% and then subtracting the volume content of retained austenite of the QP steel obtained by an X-ray diffraction method, and further the volume content of each phase in the QP steel is obtained. The novel coloring agent used in the method does not contain picric acid, is stable in solution performance, high in safety, simple in formula and easy to operate, has a very good dyeing effect on the martensite phase in the QP steel, can enable the martensite phase in the QP steel with a complex metallographic structure and relatively small retained austenite to have relatively obvious contrast with other phases, is clear in outline and easy to recognize, and furthermore, the volume content of each phase in the QP steel can be accurately and quantitatively analyzed according to a color metallographic method and an X-ray diffraction method, finally, a guarantee is provided for identification and quantitative detection of microstructures in the QP steel, research and development of products are promoted, and remarkable economic benefits and social benefits are obtained.

Description

technical field [0001] The invention belongs to the field of quantitative analysis of metallographic microstructures, in particular to a quantitative analysis method for the volume content of each phase in QP steel. Background technique [0002] QP (Quenching and Partitioning, quenching and partitioning) steel is a new type of steel plate developed in recent years to meet the high strength, high plasticity and high formability of the automotive industry. The superior performance of QP steel is mainly due to the phase transformation of retained austenite in the structure during the strain process, which transforms into martensite to produce phase transformation strengthening and plasticity improvement (deformation-induced phase transformation, QP effect), and its microstructure is generally It is composed of ferrite, martensite and retained austenite. [0003] At present, the corrosive agents used for color metallography of advanced high-strength steel are mainly Lepera reag...

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Problems solved by technology

There are also patents that try to avoid picric acid in advanced high-strength steel color metallographic technology. Chinese patent ZL201810068253.0 discloses a metallographic etchant for the staining of advanced high-strength steel residual austenite and its use. The etchant used is sulfuric acid 3.5 -15%, hydrochloric acid 12-15%, FeCl 3 7-10%, the balance is absolute alcohol, but for complex metallographic structures, the contrast between the phases of this method is usually not obvious enough, it is difficult to carry out accurate quantitative analysis, especially the retained austenite in QP steel Usually relatively small, many distributed between martensitic laths, it is difficult to identify by metallography

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