Method for discriminating bainite in hot rolled TRIP steel and calculating three phase ratio of hot rolled TRIP steel

A bainite and three-phase technology is applied in the field of identifying bainite in hot-rolled TRIP steel and calculating its three-phase comparison.

Inactive Publication Date: 2012-02-15
UNIV OF SCI & TECH BEIJING
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

The complexity of its data processing can be seen because this method cannot express bainite very clearly, but can only distinguish ferrite through the difference between the two parameters of IQ (Image Quality) or CI (Confidenc

Method used

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  • Method for discriminating bainite in hot rolled TRIP steel and calculating three phase ratio of hot rolled TRIP steel
  • Method for discriminating bainite in hot rolled TRIP steel and calculating three phase ratio of hot rolled TRIP steel
  • Method for discriminating bainite in hot rolled TRIP steel and calculating three phase ratio of hot rolled TRIP steel

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Experimental program
Comparison scheme
Effect test

Embodiment 1

[0027] 1) Take a small sample of 3.5mm×7mm×8mm on the test steel by wire cutting, roughly grind the six sides of the sample with coarse sandpaper, and finely grind the surface of the sample to be observed with fine sandpaper.

[0028] 2) Perform electrolytic polishing on the sample, the electrolyte is perchloric acid alcohol solution with glycerol (20% perchloric acid + 10% glycerin + 70% ethanol), voltage 15V, current 1.2A, polishing for 25s to remove surface stress.

[0029] 3) Use the HKL Channel 5 EBSD system equipped with the ZEISS SUPRA55 field emission scanning electron microscope to perform orientation imaging analysis on the micro-area, and select the BCC phase and the FCC phase in the phase selection;

[0030] 4) Select a step size of 0.08 μm;

[0031] 5) After the EBSD data collection is completed, open the analysis software, and analyze and process the collected EBSD data as follows:

[0032] For BCC addition of >1o small-angle grain boundaries and >15o high-angle...

Embodiment 2

[0037] 1) Take a small sample of 3.5mm×7mm×8mm on the test steel by wire cutting, roughly grind the six sides of the sample with coarse sandpaper, and finely grind the surface of the sample to be observed with fine sandpaper.

[0038] 2) Perform electrolytic polishing on the sample. The electrolyte is perchloric acid alcohol solution with glycerol (20% perchloric acid + 10% glycerin + 70% ethanol), voltage 15V, current 1.2A, polishing for 23s to remove surface stress.

[0039] 3) Use the HKL Channel 5 EBSD system equipped with the ZEISS SUPRA55 field emission scanning electron microscope to perform orientation imaging analysis on the micro-area, and select the BCC phase and the FCC phase in the phase selection;

[0040] 4) Select a step size of 0.15 μm;

[0041] 5) After the EBSD data collection is completed, open the analysis software, and analyze and process the collected EBSD data as follows:

[0042]Add two types of grain boundaries, the small-angle grain boundary of >1o ...

Embodiment 3

[0046] 1) Take a small sample of 3.5mm×7mm×8mm on the test steel by wire cutting, roughly grind the six sides of the sample with coarse sandpaper, and finely grind the surface of the sample to be observed with fine sandpaper.

[0047] 2) Perform electrolytic polishing on the sample. The electrolyte is perchloric acid alcohol solution with glycerin (20% perchloric acid + 10% glycerin + 70% ethanol), voltage 15V, current 1.2A, polishing for 20s to remove surface stress.

[0048] 3) Use the HKL Channel 5 EBSD system equipped with the ZEISS SUPRA55 field emission scanning electron microscope to perform orientation imaging analysis on the micro-area, and select the BCC phase and the FCC phase in the phase selection;

[0049] 4) Select a step size of 0.15 μm;

[0050] 5) After the EBSD data collection is completed, open the analysis software, and analyze and process the collected EBSD data as follows:

[0051] Add two types of grain boundaries, the small-angle grain boundary of >1o...

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Abstract

The invention relates to a method for discriminating bainite in a hot rolled TRIP steel and calculating a three phase ratio of the hot rolled TRIP steel. According to the method, an electron backscatter diffraction (EBSD) apparatus arranged on a scanning electron microscope is utilized to carry out quantitative measurement on FCC phase ( residual austenite) and BCC phase (ferrite+ bainite) of a hot rolled TRIP steel; processing is carried out on EBSD pattern data; a bainite structure is distinguished from the BCC phase by utilizing addition of a low angle grain boundary; Image Tool software is utilized to carry out statistics and calculation on three phase structure phase distinguishment graph of the hot rolled TRIP steel so as to obtain a content of a ferrite; and finally, a ration of the residual austenite to the ferrite to the bainite in the hot rolled TRIP steel is determined. Beneficial effects of the method is as follows: calibration on a phase structure can be carried out accurately and it is convenient to calculate all phase structures; and orientation information obtained by an EBSD technology can be utilized to carry out processing on various data according to own researches; therefore, researchers can accurately calibrate all phase structures in controlled rolling and controlled cooling steel with multi-phase structures without increased extra work.

Description

technical field [0001] The present invention relates to the identification and quantitative analysis of phases in transformation-induced plasticity multiphase structure steel (TRIP steel) with good matching of strength and plasticity, in particular to a method for identifying bainite in hot-rolled TRIP steel and calculating its three phases method. Background technique [0002] In recent years, TRIP steel for automobiles with high strength and high plasticity has attracted widespread attention. The good coordination of the three-phase structure of ferrite, bainite and retained austenite ensures the comprehensive mechanical properties of TRIP steel. . The martensitic transformation of 5-15% of the retained austenite in the steel under stress results in transformational strengthening and plastic growth. The mechanical properties of TRIP steel depend on the grain size and volume percentage of each phase in the steel, the hardening rate of the hard phase and soft phase, the l...

Claims

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Application Information

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IPC IPC(8): G01N23/22G01N23/20G01N23/203
Inventor 米振莉陈美芳江海涛李志超赵爱民
Owner UNIV OF SCI & TECH BEIJING
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