Corrosion agent of high-steel-level pipeline steel metallographic structure and display method

A corrosive, high-grade steel technology, applied in the preparation of test samples, etc., can solve the problem of not being able to display the ferrite grain size at the same time

Active Publication Date: 2011-03-30
ANGANG STEEL CO LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

Although this method can clearly show the prior-austenite grain size, it cannot also show the ferrite grain size after intra-prime austenite transformation
In the current domestic and fore

Method used

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  • Corrosion agent of high-steel-level pipeline steel metallographic structure and display method
  • Corrosion agent of high-steel-level pipeline steel metallographic structure and display method
  • Corrosion agent of high-steel-level pipeline steel metallographic structure and display method

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0015] The composition of the high-grade pipeline steel analyzed in this example is as follows (mass percentage, %): C 0.04, Si 0.16, Mn 1.65, P 0.009, S 0.002, Nb 0.06, V 0.03, Ti 0.015, Mo 0.24, Ni 0.23, Cu 0.18, Al soul 0.045, N 0.0033. After the sample is polished with a grinding wheel, it is ground on 180#, 400#, 800# and 1000# water sandpaper in turn, and then polished with 2.5 μm diamond abrasive paste on a polishing disc. After shallow etching with 4% nitric acid alcohol for 2 seconds, rinse the surface of the sample with clean water. Then re-polish, so repeated three times. Add 8 g of analytically pure (purity ≥ 99.8%) picric acid sealed in water into 100 ml of deionized water, then add 20 ml of white cat detergent, stir evenly, and then drop in 0.5 ml of 10% dilute hydrochloric acid. Heat the prepared etchant to 60°C, keep the temperature in a water bath, immerse the polished sample in the etchant for 300 seconds, and wipe the surface of the sample with cotton dur...

Embodiment 2

[0017] The composition of high-grade pipeline steel analyzed in this example is as follows (mass percentage, %): C0.06, Si 0.23, Mn 1.57, P 0.012, S 0.003, Nb 0.07, V 0.04, Ti 0.011, Mo 0.19, Ni 0.13 , Cu 0.22, Al soul 0.034, N 0.0029. After the sample is ground, ground and polished, it is lightly corroded with 4% nitric acid alcohol for 3 seconds, and then the surface of the sample is rinsed with clean water. Polish again, so repeat three times. Add 7g of analytically pure picric acid into 100ml of deionized water, then add 20ml of white cat detergent, and stir evenly. Then 1ml of 10% dilute hydrochloric acid was added dropwise. Heat the prepared etchant to 70°C and keep the temperature constant in a water bath. Then immerse the processed sample in the etchant and corrode for 200 seconds, during which time the surface of the sample was wiped with cotton. Rinse the surface of the sample with clean water immediately after the corrosion, and observe after drying. Observati...

Embodiment 3

[0019] The composition of the high-grade pipeline steel analyzed in this example is as follows (mass percentage, %): C0.05, Si 0.15, Mn 1.72, P 0.011, S 0.003, Nb 0.06, V 0.03, Ti 0.014, Mo 0.18, Ni 0.15 , Cu 0.23, Al soul 0.055, N 0.0035. After the sample is ground, ground, and polished, it is lightly etched with 4% nitric acid alcohol solution for 3 seconds, and then the surface of the sample is rinsed with clean water. Repeat this three times. Add 8g of analytically pure picric acid into 100ml of deionized water, then add 20ml of white cat detergent, and stir evenly. Then 0.8 ml of 10% dilute hydrochloric acid was added dropwise. Heat the prepared etchant to 68°C and keep the temperature constant in a water bath. Then immerse the polished sample in the etchant and corrode for 220 seconds, during which time the surface of the sample was wiped with cotton. Rinse the surface of the sample with clean water immediately after the corrosion, and observe after drying. Observa...

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Abstract

The invention provides a corrosion agent of a high-steel-level pipeline steel metallographic structure and a display method. The corrosion agent consists of 1 to 10g of analysis pure picric acid with the purity higher than or equal to 99.8 percent, 100ml of deionized water, 0.1 to 2ml of 10 percent diluted hydrochloric acid and 5 to 25ml of liquid detergent. The display method comprises the following steps of: 1. preparation of the corrosion agent: adding and dissolving 1 to 10g of the analytically pure picric acid into 100ml of the deionized water, uniformly stirring, then dripping 5 to 25mlof the liquid detergent, adding 0.1 to 2ml of the diluted hydrochloric acid, and uniformly stirring; 2. specimen processing: carrying out corrosion for 0.5 to 5 seconds in nitric acid alcohol solution after the specimen polishing, carrying out flowing flushing by clean water, and repeating the operation for 2 to 5 times in such a way; and 3. specimen corrosion: heating the corrosion agent to 50 to 100 DEG C, maintaining the constant temperature at the same time of soaking the specimen into the corrosion agent for 60 to 600 seconds, and continuously wiping the surface of the specimen by cotton. When the invention is adopted, not only various ferritic structures but also the original austenitic grain boundaries can be displayed on the high-steel-level pipeline steel metallographic structure.

Description

technical field [0001] The invention belongs to the technical field of metallographic inspection and analysis, in particular to a display technology for the metallographic structure of hot-rolled steel plates of high-grade pipeline steel. Background technique [0002] High steel grade (X70 and above steel grade) pipeline steel is widely used in the construction of long-distance pipelines in the world because of its excellent strength, toughness, weldability and HIC resistance. The method of displaying the metallographic structure of high-grade pipeline steel is mainly to use nitric acid alcohol etchant. Using this corrosive agent can clearly display various ferrite structures, but in most cases the original austenite grain boundaries cannot be clearly displayed. If you want to observe the original austenite grain boundary, you generally use saturated picric acid solution as the etchant, and corrosion with this etchant usually only shows the original austenite grain boundary...

Claims

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Application Information

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IPC IPC(8): G01N1/32
Inventor 沙庆云乔立峰黄国建关菊
Owner ANGANG STEEL CO LTD
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