Method for displaying austenite grain boundary of low-carbon micro-alloy steel

A technology of austenite grain boundaries and alloy steel, applied in the field of physical detection, can solve problems such as low efficiency and long erosion time, achieve reasonable control of process parameters and ensure product performance

Inactive Publication Date: 2012-06-20
INNER MONGOLIA BAOTOU STEEL UNION
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  • Abstract
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  • Application Information

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Problems solved by technology

[0003] Chinese patent CN86105938 discloses "a new method for displaying grain boundaries of copper-rare earth alloys". The main commonly used etchant preferentially etches the rare earth elements in copper, which brings insurmountable difficulties to the research and observation of the solid solution and distribution of rare earth elements in copper.
The disadvantage is that it is only good for displaying the austenite grain boundary of copper-rare earth alloy, but it is not known for low carbon microalloy steel
The disadvantage is that the sample erosion time is as long as 40-60min, and the efficiency is low
The disadvantage is that it is suitable for medium and high carbon steels, and it is not mentioned for low carbon microalloyed steels

Method used

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  • Method for displaying austenite grain boundary of low-carbon micro-alloy steel
  • Method for displaying austenite grain boundary of low-carbon micro-alloy steel
  • Method for displaying austenite grain boundary of low-carbon micro-alloy steel

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0019] The chemical composition of the sample is by weight percentage: C: 0.045%, Si: 0.195%, Mn: 1.62%, P: 0.008%, S: <0.002%, Nb: 0.06%, Cr: 0.19%, Mo: 0.19% , Ni: 0.21%, Ti: 0.011%, Alt: 0.03%, N: 0.0040%, belonging to low-carbon microalloyed steel;

[0020] The specific erosion method is:

[0021] (1), sample preparation: after quenching, the iron oxide scale on the surface of the sample with a size of 20 mm × 15 mm × 15 mm was ground off, and then finely ground on metallographic sandpaper with a grain size of 240, 400, 600, 800, and 1000, Grinding and polishing on a polishing machine should ensure that the polished surface of the sample is free from any scratches, pits, pits, stains and other defects.

[0022] (2) Preparation of etchant and erosion method: Put a small beaker of φ60mm×70mm containing 80ml of distilled water into a large beaker of φ90mm×120mm filled with water (200mL), and heat it in a constant temperature and timing water bath First, put 2.5g of picric a...

Embodiment 2

[0024] The chemical composition of the sample is by weight percentage: C: 0.075%, Si: 0.038%, Mn: 1.16%, P: 0.001%, S: 0.002%, Nb: 0.09%, Ti: 0.008%, La: 0.018%, Alt: 0.026%, N: 0.0046%, belongs to low carbon microalloy steel;

[0025] The specific erosion method is:

[0026] (1), sample preparation: prepare sample according to the method for preparing sample in embodiment 1,

[0027] (2), etchant preparation and erosion method: put a small beaker of φ60mm×70mm with 80ml of distilled water into a large beaker of φ90mm×120mm with 200mL of water, and heat it in a constant temperature and timing water bath. Put 2.5g of picric acid and 1g of seagull brand shampoo into a small beaker of φ60mm×70mm for heating, when the indicated temperature is 38°C, add 0.4ml of xylene with a concentration of 78% and 0.5g of copper chloride and stir , when the indicated temperature is 50°C, add 0.3ml of hydrochloric acid with a concentration of 80% and 0.3ml of hydrofluoric acid with a concentrat...

Embodiment 3

[0029] The chemical composition of the sample is by weight percentage: C: 0.062%, Si: 0.304%, Mn: 1.60%, P: 0.010%, S: 0.002%, Nb: 0.038%, Cr: 0.35%, Mo: 0.18%, Ni: 0.18%, Ti: 0.010%, B: 0.0007%, belonging to low-carbon boron-containing microalloy steel,

[0030] The method for preparing the sample The preparation of the sample and the erosion method are the same as in Example 1, wherein the proportioning of the corrosive reagent is: 2.5g picric acid, 1g Seagull brand shampoo, concentration of 0.3ml of 80% xylene, 0.5g chlorinated Copper, 0.35ml of hydrochloric acid with a concentration of 80% and 0.3ml of hydrofluoric acid with a concentration of 80%, the etching time is 20s, image 3 The austenite grains of the corroded sample were magnified 200 times under a metallographic microscope.

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Abstract

The invention provides a method for displaying an austenite grain boundary of low-carbon micro-alloy steel, which belongs to the technical field of physical testing and is used for solving the problem that the low-carbon micro-alloy steel cannot clearly display austenite crystalline grains of the low-carbon micro-alloy steel. The method is characterized in that according to the reagent ratio, corrodent comprises 70-100mL of distilled water, 1-2g of seagull-brand shampoo paste, 1.8-2.5g of picric acid, 0.1-lml of dimethylbenzene with concentration larger than 60%, 0.1-lml of hydrochloric acid with concentration larger than 70%, 0.1-lml of hydrofluoric acid with concentration larger than 70% and 0.1-1g of copper chloride. The polishing-grinding surface of a test sample is guaranteed to be free of any deflects of scratches, pocks, pits, stains and the like during preparation of the test sample. By utilizing specific corrodent to be matched with an appropriate corrosion method, the method can clearly display the austenite grain boundary, provides a significant theoretical basis for researches carried out by manufacturing enterprises on influences of technological parameters on microstructure evolution in the deformation process of the steel, and can play important role on reasonably controlling the process parameters and guaranteeing product performance when the low-carbon micro-alloy steel is produced.

Description

technical field [0001] The invention belongs to the technical field of physical detection, and in particular relates to a method for displaying austenite grain boundaries of low-carbon microalloy steel. Background technique [0002] The austenite grain size of steel has a great influence on the strength, toughness and fatigue performance of steel. It plays an important role in studying the evolution law of material structure in the process of steel production, reasonably controlling process parameters and ensuring product performance. Therefore, the detection of austenite grain size is of great significance, and its display method has been continuously explored, innovated and improved by the majority of industry insiders. Whether the austenite grains can be clearly displayed depends on many factors such as the chemical composition of the sample, the state of heat treatment, the etching time, the etching method, and the etching reagent. Commonly used display methods mainly i...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): G01N1/32
Inventor 杨雄宋文钟吴鹏飞康利明王宴秋
Owner INNER MONGOLIA BAOTOU STEEL UNION
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