阅读说明：本技术 一种trip钢中马氏体含量的定量分析方法 (Quantitative analysis method for martensite content in TRIP steel ) 是由 王德宝 杨峥 牟祖茂 徐辉 程志远 宋鑫晶 于 2020-06-01 设计创作，主要内容包括：本发明属于金相显微组织定量分析方法领域,涉及一种TRIP钢中马氏体含量的定量分析方法,具体涉及一种采用彩色金相和X射线衍射方法测定TRIP钢中马氏体含量的方法,具体包括：(1)采用彩色金相法测得TRIP钢中马氏体和残余奥氏体的总含量；(2)检测TRIP钢的X射线衍射图谱,依据《钢中残余奥氏体定量测定X射线衍射仪法》计算残余奥氏体含量；(3)将彩色金相定量得到的马氏体和残余奥氏体的总含量,减去X射线衍射法得到的残余奥氏体含量,即可得到TRIP钢中的马氏体含量,所述含量为体积含量。(The invention belongs to the field of quantitative analysis methods of metallographic microstructure, relates to a quantitative analysis method of martensite content in TRIP steel, and particularly relates to a method for determining the martensite content in TRIP steel by adopting a color metallographic phase and an X-ray diffraction method, which specifically comprises the following steps: (1) measuring the total content of martensite and residual austenite in the TRIP steel by adopting a color metallographic method; (2) detecting an X-ray diffraction spectrum of the TRIP steel, and calculating the content of the residual austenite according to an X-ray diffractometer method for quantitatively determining the residual austenite in the steel; (3) and subtracting the residual austenite content obtained by the X-ray diffraction method from the total content of martensite and residual austenite obtained quantitatively by the color metallographic phase to obtain the martensite content in the TRIP steel, wherein the content is volume content.)

1. A quantitative analysis method for the martensite content in TRIP steel is characterized by comprising the following steps:

(1) measuring the total content of martensite and residual austenite in the TRIP steel by adopting a color metallographic method;

(2) detecting an X-ray diffraction spectrum of the TRIP steel, and determining the content of the residual austenite according to an X-ray diffractometer method for quantitatively determining the residual austenite in the steel;

(3) and subtracting the residual austenite content obtained by the X-ray diffraction method from the total content of martensite and residual austenite obtained quantitatively by the color metallographic phase to obtain the martensite content in the TRIP steel.

2. The quantitative analysis method of claim 1, wherein the color metallographic method in the step (1) is to observe the microstructure of the TRIP steel under a metallographic microscope, the ferrite is light blue, the bainite is brown, the retained austenite and the martensite are white, and then the white phase is quantified by using metallographic analysis software to obtain the total content of the martensite and the retained austenite.

3. The quantitative analysis method according to claim 1, wherein the TRIP steel of step (1) is treated by the following method before observation under a metallographic microscope:

(1) selecting TRIP steel produced in industry, cutting into blocks, cold embedding, and then grinding and polishing;

(2) eroding the sample by using 2-4 wt% of nitric acid alcohol for 5-10 seconds until the polished surface of the sample is changed from bright to dark, and then slightly polishing to eliminate the trace etched by the nitric acid alcohol;

(3) and (2) putting the sample into a corrosive agent for corrosion at room temperature, wherein the proportion of the corrosive agent is that 1-2 wt% of sodium metabisulfite aqueous solution and 2-4 wt% of picric acid alcohol solution are mixed according to the proportion of 1 (0.8-1.2), the corrosion time is 30-60 seconds, and when the sample surface is blue and orange, the sample surface is washed by alcohol and dried.

4. The quantitative analysis method according to claim 1, wherein the TRIP steel size-selecting slit of step (2) ensures that X-rays do not irradiate the outside of the sample.

5. The quantitative analysis method of claim 1, wherein the X-ray diffraction pattern of the TRIP steel in step (2) is obtained by using an X-ray diffractometer, setting the test conditions to Co target K α radiation, operating voltage of 30-35Kv, operating current of 35-45mA, step size of 0.02 °, and scanning range of 40 ° -110 °, and selecting a slit according to sample size to ensure that the X-ray does not irradiate outside the sample.

6. The quantitative analysis method according to claim 1, wherein the content is a volume content.

Technical Field

The invention belongs to the field of quantitative analysis methods of metallographic microstructure, relates to a quantitative analysis method of martensite content in TRIP steel, and particularly relates to a method for determining the martensite content in TRIP steel by adopting a color metallographic phase and an X-ray diffraction method.

Background

TRIP (Transformation Induced Plasticity) steel is a new type of steel sheet developed in recent years to satisfy the automotive industry for high strength, high Plasticity, and high formability. The TRIP steel has the advantages that the residual austenite in the structure is transformed into martensite during the strain process to generate the phase transformation strengthening and the plasticity improvement (deformation induced phase transformation, TRIP effect), and the microstructure of the TRIP steel generally consists of ferrite, bainite, residual austenite and a small amount of martensite.

At present, the structure quantification of the TRIP steel mainly aims at the quantification of residual austenite, and the quantification of martensite is rarely related, but due to the production process, a certain amount of martensite is inevitably existed in the TRIP steel, and the content of the martensite influences the exertion of the TRIP effect to a certain extent. Chinese patent ZL200810048973.7 discloses a method for displaying and quantitatively detecting residual austenite or island martensite-austenite in TRIP steel, which mainly comprises the steps of identifying and quantitatively analyzing each phase structure of the TRIP steel by using a color metallographic method, but because the color and the appearance of the residual austenite and the martensite are similar under the color metallographic condition and are white, the residual austenite and the martensite are difficult to distinguish by using an image method, the residual austenite and the martensite cannot be well distinguished by the method, and the finally obtained quantitative result actually contains the common content of the residual austenite and the martensite.

On the basis of the invention, the content of the retained austenite and the martensite in the TRIP steel is quantified by two steps by adopting a color metallographic phase and an X-ray diffractometer.

Disclosure of Invention

The invention discloses a quantitative analysis method for martensite content in TRIP steel, which is characterized by comprising the following steps:

(1) measuring the total content of martensite and residual austenite in the TRIP steel by adopting a color metallographic method;

(2) detecting the X-ray diffraction pattern of the TRIP steel, and determining the content of the residual austenite according to YB/T5338-2006X-ray diffractometer method for quantitatively determining the residual austenite in the steel;

(3) and subtracting the residual austenite content obtained by the X-ray diffraction method from the total content of martensite and residual austenite obtained quantitatively by the color metallographic phase to obtain the martensite content in the TRIP steel.

Preferably, the color metallographic method in the step (1) is to observe a microstructure of the TRIP steel under a metallographic microscope, the ferrite is light blue, the bainite is brown, and the retained austenite and martensite are white, and then quantify the white phase by using metallographic analysis software to obtain the total content of the martensite and the retained austenite.

Preferably, the TRIP steel of step (1) is treated by the following method before observation under a metallurgical microscope:

(1) selecting TRIP steel produced in industry, cutting into blocks, cold embedding, and then grinding and polishing;

(2) eroding the sample by using 2-4 wt% of nitric acid alcohol for 5-10 seconds until the polished surface of the sample is changed from bright to dark, and then slightly polishing to eliminate the trace etched by the nitric acid alcohol;

(3) the sample is put into a corrosive agent for corrosion at room temperature, the proportion of the corrosive agent is that 1 wt% -2 wt% of sodium metabisulfite aqueous solution and 2 wt% -4 wt% of picric acid alcohol solution are mixed according to the proportion of 1 (0.8-1.2), preferably 1 (1-1.1) (the specific proportion can be determined according to C, Si content in TRIP steel), the corrosion time is 30 seconds-60 seconds, and when the sample surface is blue-orange, the sample surface is washed by alcohol and dried.

Preferably, the TRIP steel size selection slit of step (2) ensures that X-rays do not irradiate the outside of the sample.

Preferably, the X-ray diffraction pattern of the TRIP steel in the step (2) is obtained by using an X-ray diffractometer, setting the test conditions to Co target K alpha radiation, working voltage of 30-35Kv, working current of 35-45mA, step size of 0.02 degrees and scanning range of 40-110 degrees, and selecting a slit according to the size of the sample to ensure that the X-ray does not irradiate the outside of the sample, thereby obtaining the X-ray diffraction pattern.

Preferably, the content is a volume content.

According to the method, the martensite content in the trip steel can be well determined.

Drawings

The invention is further described below with reference to the accompanying drawings.

FIG. 1 color metallographic photograph of TRIP steel in example 1 of the present invention.

FIG. 2X-ray diffraction pattern of TRIP steel in example 1 of the present invention.

Detailed Description

The present invention will be further described with reference to the following examples. The described embodiments and their results are only intended to illustrate the invention and should not be taken as limiting the invention described in detail in the claims.