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Method for detecting depth of austenite heat-resistant steel pipe inner wall shot blasting layer

A technology for the inner wall of a steel pipe and a detection method, which is applied in the direction of measuring devices, preparation of test samples, instruments, etc., can solve the problems of long detection time, singleness, and limitation to chemical etching methods, etc., and achieve good reproducibility and reproducibility. The etching operation is simple and the display effect is obvious

Pending Publication Date: 2021-03-16
DONGFANG BOILER GROUP OF DONGFANG ELECTRIC CORP
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

At present, the metallographic method to detect the depth of the shot peening layer of S30432 steel pipe is relatively simple, and is mainly limited to the chemical etching method.
The chemical etching method that adopts at present, some reagent composition and preparation are comparatively complicated, and detection time is long, as publication number is that the Chinese invention patent application of CN105372246A discloses a kind of corrosive agent for detecting austenitic stainless steel surface blasting layer and Its use method, wherein the corrosive agent component is composed of hydrochloric acid, glycerin, nitric acid, and picric acid ethanol solution, and its volume fraction is: hydrochloric acid: 25% to 31%; glycerol: 26% to 28%; nitric acid: 12% ~ 16%; picric acid ethanol solution: 25% ~ 35%; some also use more toxic chemical reagents, such as the Chinese invention patent with publication number CN101760742A, which uses highly toxic hydrogen that is harmful to the human body Fluoric acid reagents, which limit the popularization and application of chemical etching methods, and the existing conventional electrolytic etching methods cannot clearly display the depth area of ​​the shot peening layer on the inner surface of the sample

Method used

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  • Method for detecting depth of austenite heat-resistant steel pipe inner wall shot blasting layer
  • Method for detecting depth of austenite heat-resistant steel pipe inner wall shot blasting layer
  • Method for detecting depth of austenite heat-resistant steel pipe inner wall shot blasting layer

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Experimental program
Comparison scheme
Effect test

Embodiment 1

[0021] (1) Sample pretreatment: After shot blasting the inner wall of the SA-213S30432 steel pipe, select the sample. The shape of the sample is 15mm long and 20mm wide along the steel pipe lengthwise; Heat it to 650°C in a resistance furnace, then keep it warm for 1 hour, take out the sample and cool it to room temperature in the air;

[0022] (2) Preparation of etchant: 100mL of absolute ethanol is placed in a container, then 7mL of nitric acid is added and stirred evenly, then 7mL of hydrochloric acid is added and stirred evenly to obtain etchant; the mass percentage of the nitric acid is 65%, and the hydrochloric acid The mass percentage is 36%, and the mass percentage of the absolute ethanol is ≥99.7%;

[0023] (3) Electrolytic etching: Grind and polish the sample pretreated in step (1), put it into the etchant obtained in step (2), and take it out after electrolytic etching for 12 seconds. At this time, the polished surface of the sample is covered with a A uniform blac...

Embodiment 2

[0026] (1) Sample pretreatment: After shot blasting the inner wall of the SA-213S30432 steel pipe, select the sample. The shape of the sample is 20 mm long and 25 mm wide along the steel pipe lengthwise; Heat it to 650°C in a resistance furnace, then keep it warm for 1 hour, take it out for testing, and cool it to room temperature in the air;

[0027] (2) Preparation of etchant: 120mL of absolute ethanol is placed in a container, then 10mL of nitric acid is added and stirred evenly, then 10mL of hydrochloric acid is added and stirred evenly to obtain etchant; the mass percentage of the nitric acid is 68%, and the hydrochloric acid The mass percentage is 38%, and the mass percentage of the absolute ethanol is ≥99.7%;

[0028] (3) Electrolytic etching: Grind and polish the sample pretreated in step (1), put it into the etchant obtained in step (2), and take it out after electrolytic etching for 15 seconds. At this time, the polished surface of the sample is covered with a A uni...

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Abstract

The invention discloses a method for detecting the depth of an austenite heat-resistant steel pipe inner wall shot blasting layer, which comprises the following steps of (1) removing oil from a sampleto be etched, drying, heating to 640-660 DEG C, keeping the temperature for 0.5-1 hour, taking out, and cooling, (2) putting absolute ethyl alcohol into a container, adding nitric acid, uniformly stirring, adding hydrochloric acid, and uniformly stirring to obtain an etching agent, and (3) grinding and polishing the sample pretreated in the step (1), putting the sample into the etchant obtained in the step (2) for electrolytic etching for 10-15 seconds, then taking out the sample, washing the sample with clear water, then washing the sample with absolute ethyl alcohol, and then blow-drying ordrying the sample with hot air so as to be observed by using a microscope, wherein the voltage of the electrolytic etching is 6.5 V to 7.5 V. According to the method, the to-be-tested sample is subjected to heating and heat preservation treatment firstly, then the etching agent composed of nitric acid-hydrochloric acid-absolute ethyl alcohol is selected for electrolytic etching, the depth area ofthe shot blasting hardened layer on the inner wall of the S30432 steel pipe can be clearly and completely displayed, and therefore the depth of the shot blasting layer can be conveniently and accurately measured.

Description

technical field [0001] The invention relates to the technical field of austenitic heat-resistant steel detection, in particular to a method for detecting the depth of a shot peening layer on the inner wall of an austenitic heat-resistant steel pipe. Background technique [0002] Since its inception, austenitic heat-resistant stainless steel has been playing an important role in stainless steel due to its good comprehensive properties, and its production and use account for about 70% of the total production and use of stainless steel. S30432 is a new type of fine-grained austenitic heat-resistant steel developed on the basis of ASME SA-213TP304H. Its maximum service temperature can be as high as 705°C. The preferred material for components in the high-temperature section is currently widely used in high-temperature superheaters and reheaters of ultra-(super)critical boilers in my country. With the improvement of boiler parameter grades, higher and higher requirements are put ...

Claims

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Application Information

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IPC IPC(8): G01N1/32G01N21/84C23F1/10C25F3/06
CPCG01N1/32G01N21/84C23F1/10C25F3/06Y02E30/30
Inventor 曾辉杨金炳普晓明张林于明明邓钱元
Owner DONGFANG BOILER GROUP OF DONGFANG ELECTRIC CORP