Etching method of corrosion agent for displaying crystal boundary of quenched and tempered low-alloy chrome molybdenum steel austenite crystal grains

A technology of austenite grains and etchant, which is applied in the field of etching of austenite grain boundary etchant of low alloy chromium molybdenum steel in quenched and tempered state. The effect of short time, convenient operation and easy preparation

Active Publication Date: 2016-08-17
TIANJIN PIPE GROUP CORP
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0004] Picric acid, 2.4.6-trinitrophenol is a kind of explosives, abbreviated TNP, PA, the pure substance is a slightly yellow crystal at room temperature, bitter, poisonous, strong explosive, and has a great safety hazard

Method used

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  • Etching method of corrosion agent for displaying crystal boundary of quenched and tempered low-alloy chrome molybdenum steel austenite crystal grains
  • Etching method of corrosion agent for displaying crystal boundary of quenched and tempered low-alloy chrome molybdenum steel austenite crystal grains
  • Etching method of corrosion agent for displaying crystal boundary of quenched and tempered low-alloy chrome molybdenum steel austenite crystal grains

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0024] This example uses low-alloy chromium-molybdenum steel made of 26CrMo4, the mass percentage of which is C 0.24%-0.27%, Si 0.23%-0.28%, Mn 0.89%-0.94%, Cr 0.84%-0.92%, Mo0.16 %-0.19%. Tempering treatment.

[0025] The ratio of the metallographic etchant is: 8g of sulfosalicylic acid, 100mL of water, 1mL of nitric alcohol with a mass percentage of 4%, and 0.5mL of detergent.

[0026] Etching is carried out as follows:

[0027] 1. Sample production: After the cut sample is polished with a sample grinder, it is polished with W2.5 polishing paste to make the polished surface a smooth mirror surface without scratches.

[0028] 2. Proportion of corrosive agent: first configure the nitric acid alcohol with a mass percentage concentration of 4%, then dissolve 8g sulfosalicylic acid in 100mL water, stir well, pour it into a glass dish, add 1mL nitric acid alcohol (mass. The percentage concentration is 4%), 0.5mL detergent, and then put absorbent cotton into it, and let the abso...

Embodiment 2

[0032] This example adopts the low-alloy chromium-molybdenum steel of 27CrMo47Vs, the mass percent of its composition is C 0.24%-0.27%, Si 0.23%-0.31%, Mn 0.40%-0.49%, Cr0.96%-1.01%, Mo0. 74%-0.80%. Tempering treatment.

[0033] The proportioning of the metallographic etchant is: 10g of sulfosalicylic acid, 100mL of water, 0.5mL of nitric alcohol (concentration of 4% by mass), and 1mL of detergent.

[0034] Etching is carried out as follows:

[0035] 1. Sample production: After the cut sample is polished with a sample grinder, it is polished with W2.5 polishing paste to make the polished surface a smooth mirror surface without scratches.

[0036] 2. Proportion of corrosive agent: first configure the nitric acid alcohol with a concentration of 4% by mass percentage, then dissolve 15g of sulfosalicylic acid in 100mL of water, stir evenly, pour it into a glass dish, and add 0.5mL of nitric acid alcohol ( mass percent concentration is 4%), 1mL of detergent, and then put absorbe...

Embodiment 3

[0040] This example adopts the low-alloy chromium-molybdenum steel of 27CrMo44s, the mass percent of its composition is C 0.25%-0.28%, Si 0.21%-0.26%, Mn 0.62%-0.70%, Cr1.02%-1.10%, Mo0. 40%-0.43%. Tempering treatment.

[0041] The proportioning of the metallographic etchant is: 10g of sulfosalicylic acid, 100mL of water, 0.3mL of nitric alcohol (concentration of 4% by mass), 1mL of detergent.

[0042] Etching is carried out as follows:

[0043] 1. Sample production: After the cut sample is polished with a sample grinder, it is polished with W2.5 polishing paste to make the polished surface a smooth mirror surface without scratches.

[0044] 2. Proportion of corrosive agent: first configure nitric alcohol with a concentration of 4% by mass percentage, then dissolve 10 g of sulfosalicylic acid in 100 mL of water, stir well, pour it into a glass dish, and add 0.3 mL of nitric acid alcohol ( mass percent concentration 4%), 1mL of detergent, and then put absorbent cotton into i...

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Abstract

The invention provides an etching method of a corrosion agent for displaying the crystal boundary of quenched and tempered low-alloy chrome molybdenum steel austenite crystal grains. The method comprises the following steps: preparing the corrosion agent; putting absorbent cotton in a glass dish containing the corrosion agent to make the absorbent cotton adsorb the corrosion agent; cleaning a polished low-alloy chrome molybdenum steel sample, blowing the sample until the sample is dry, immersing the dry sample in the corrosion agent, arranging the immersed sample on the absorbent cotton in a manner that the polished surface of the sample is downward, immersing for 10-15min, taking out the sample, cleaning the sample with clear water, cleaning the sample with anhydrous ethanol, and blowing the cleaned sample until the sample is dry; and rating the grain size of the quenched and tempered low-alloy chrome molybdenum steel austenite crystal grains under a microscope. The method has the advantages of simple preparation of the corrosion agent, no need of water bath heating, realization of large-batch evaluation of the grain size grade in 10-15min, safe operation, and high convenience.

Description

technical field [0001] The invention relates to a metallographic etchant, in particular to an etching method for an austenite grain boundary etchant of a low-alloy chromium-molybdenum steel showing quenched and tempered state. Background technique [0002] Grain size in steel is an important characteristic of steel performance, which obviously affects the impact toughness, strength, plasticity and machinability of steel. Therefore, it is of great significance to detect the austenite grain size. [0003] The metallographic structure of quenched and tempered low-alloy chromium-molybdenum steel is mostly tempered sorbite, and sometimes partially tempered bainite. At present, for the evaluation of the austenite grain size of low-alloy chromium-molybdenum steel in the quenched and tempered state, the corrosive agent used is a solution containing picric acid, including picric acid alcohol solution and picric acid aqueous solution as corrosive agents, and an appropriate amount of ...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): G01N1/32
CPCG01N1/32
Inventor 赵苏娟张冰李志群侯强孙徕博岳世斌
Owner TIANJIN PIPE GROUP CORP
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