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

A volume content, martensite technology, applied in the analysis of materials, material analysis through optical means, material analysis using wave/particle radiation, etc., can solve the problems of insufficient contrast and difficult quantitative analysis, etc., to achieve formula Simple, promote product research and development, and stable performance

Active Publication Date: 2022-01-07
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AI-Extracted Technical Summary

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...
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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.

Application Domain

Material analysis using wave/particle radiationPreparing sample for investigation +2

Technology Topic

Picric acidDyeing +7


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


  • Experimental program(1)

Example Embodiment

[0020] Example 1
[0021] Following the step of detecting the volume fraction of each phase steel QP:
[0022] (1) Preparation of color metallography etchant: 3mL of concentrated hydrochloric acid was added 50mL of water and mixed with 50mL ethanol, and finally 5g sodium metabisulfite powder added to the mixture, followed by rapid stirring with a glass rod, so that the powder was completely dissolved, sodium metabisulfite, after allowed to stand in a fume hood 2-5min;
[0023] (2) Sample pretreatment: Select QP980 industrial production of steel (martensite content of about 60% by volume, the ferrite content of about 30% by volume of residual austenite volume fraction of about 10%) of the study, the QP cut and cooled steel inlay, followed by grinding and polishing; of step (1) preparation of sample color metallographic etchant 10-30 seconds, while the edge corrosion was observed when the sample surface turned dark to a bright, then the surface of the specimen flush with water, and wiped with a cotton hard, the surface can not have residual stain, rinsed with alcohol and finally dried;
[0024] (3) QP steel microstructure was observed under the optical microscope, such as figure 1 As shown in martensite as a dark region (dark brown color metallography drawing), and then using metallographic analysis software quantitative analysis relative to the dark area, a total volume of martensite content of 62% (volume ratio, the same below);
[0025] (4) The metallographic specimens by X-ray diffraction pattern for diffraction analysis, determining the volume fraction of retained austenite tissue, test conditions Cu Kα radiation target, voltage 40kV, 40mA operating current, step size 0.02 °, scan range 47 ° -94 °, to ensure that the sample size selection slit according to the X-ray is not irradiated to the outside of the sample, such as to give figure 2 As shown in X-ray diffraction pattern, based YB / T5338-2006 "quantitative determination of retained austenite X-ray diffractometer" calculate residual austenite volume fraction of 10.75%;
[0026] (5) using a quantitative metallography color 100% minus the amount of 62% martensite, residual austenite volume fraction minus obtained 10.75% X-ray diffraction method, to obtain the volume fraction of ferrite in the steel QP 27.25%, thereby obtaining steel QP volume fraction of each phase.
[0027] The test results of Example embodiment industrial production of large QP980 similar known composition of steel, the present invention show novel stains of QP martensitic steel has very good dyeing effect, enables the complex microstructure, residual QP is relatively small austenite steel having a martensitic phase and other phases of the liner obvious, and capable of QP steel volume fraction of each phase accurate quantitative metallographic analysis and color analysis according to X-ray diffraction.


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