Method for displaying P91 and P92 steel original austenite grain boundaries

A technology of austenite grain boundary and display method, applied in the field of physical and chemical inspection, can solve problems such as no exposure problem, large human factors and measurement errors, measurement accuracy and precision failing to meet inspection requirements, etc. degree, cost, pollution-free, and the effect of improving resolution

Active Publication Date: 2012-07-18
DONGFANG BOILER GROUP OF DONGFANG ELECTRIC CORP
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

This method has a certain effect on carbon steel and quenched and tempered steel with low content of alloying elements, but it is difficult to completely and clearly display the grain boundary of original austenite in steel with high content of alloying elements such as P91 and P92. The display effect is not ideal (as shown in the attached picture figure 1 , figure 2 shown), the samples failed to meet the inspection requirements in terms of grain boundary display integrity, reproducibility and operational stability
Since it is difficult to completely and clearly display the original austenite grain boundary of P91 and P92 steel, the detection of the original austenite grain size of such materials cannot be carried out
The original austenite grain size can only be roughly estimated based on the orientation of the structure. Human factors and measurement errors are relatively large, and the measurement accuracy and precision cannot meet the inspection requirements. problems affecting the quality control of such materials

Method used

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  • Method for displaying P91 and P92 steel original austenite grain boundaries
  • Method for displaying P91 and P92 steel original austenite grain boundaries
  • Method for displaying P91 and P92 steel original austenite grain boundaries

Examples

Experimental program
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Effect test

Embodiment 1

[0039] A method for displaying prior austenite grain boundaries of P91 and P92 steels, comprising the following steps in sequence:

[0040] 1) Chemical heat corrosion: add 4 grams of sodium dodecylbenzenesulfonate to 100ml of supersaturated picric acid aqueous solution, and heat and stir until sodium dodecylbenzenesulfonate is completely dissolved in the saturated solution of picric acid, then add 2ml of hydrogen peroxide, prepared as a chemical corrosion solution. Immerse the polished sample in the chemical corrosion solution first, and care should be taken to keep the polished surface of the sample out of contact with the container. It is best to make the polished surface of the sample face up. After heating and boiling for 3 minutes, take out the sample and wash it with clean water. hot air drying;

[0041] 2) Electrolytic etching: use 10% by volume sulfuric acid aqueous solution as the electrolytic etching solution, immerse the chemically etched sample in an electrolytic ...

Embodiment 2

[0044] Example 2: The mode of operation of this embodiment is the same as that of Embodiment 1, the difference is that:

[0045] A method for displaying prior austenite grain boundaries of P91 and P92 steels, comprising the following steps in sequence:

[0046] 1) Chemical thermal corrosion: Dissolve 2 grams of sodium tridecylbenzenesulfinate completely in 100 ml of supersaturated picric acid aqueous solution, and then add 3 ml of hydrogen peroxide to prepare a chemical corrosion solution. Immerse the polished sample in the chemical corrosion solution, heat, boil and etch for 2 minutes, then take out the sample to clean and dry;

[0047] 2) Electrolytic etching: use 15% sulfuric acid aqueous solution as the electrolytic etching solution to electrolytically etch the sample after chemical thermal etching; electrolytic specification: voltage 25V, time 90S;

[0048] 3) Microscopic observation: through the dark field illumination of the microscope, the original austenite grain bou...

Embodiment 3

[0050] Example 3: The mode of operation of this embodiment is the same as that of Embodiment 1, the difference is that:

[0051] A method for displaying prior austenite grain boundaries of P91 and P92 steels, comprising the following steps in sequence:

[0052] 1) Chemical thermal corrosion: Dissolve 5 grams of sodium dodecylbenzenesulfonate completely in 120 ml of supersaturated picric acid aqueous solution, and then add 4 ml of hydrogen peroxide to prepare a chemical corrosion solution. Immerse the polished sample in the chemical corrosion solution, heat, boil and etch for 5 minutes, then take out the sample to clean and dry;

[0053] 2) Electrolytic etching: use 10% by volume sulfuric acid aqueous solution as the electrolytic etching solution, and electrolytically etch the sample after chemical thermal etching; electrolytic specification: voltage 15V, time 80S;

[0054] 3) Microscopic observation: through the dark field illumination of the microscope, the original austen...

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Abstract

The invention discloses a method for displaying P91 and P92 steel original austenite grain boundaries, which belongs to the field of physical and chemical inspection. A sample which is well ground and polished is subjected to a corrosion method which combines supersaturated picric acid-sodium dodecyl benzene sulfonate (or sodium tridecyl benzene sulfinic acid)-hydrogen peroxide thermal etching and sulfuric acid electrolytic pickling, through utilizing microscope dark-ground illumination or bright-ground illumination of the light polished sample, the P91 and P92 steel original austenite grain boundaries can be displayed. The method disclosed by the invention is safe to operate, low in cost and pollution-free; and by the method, the P91 and P92 steel original austenite grain boundaries can be clearly and completely displayed, the grain size grades of P91 and P92 steel are accurately evaluated, and a basis is provided for material quality control.

Description

technical field [0001] The invention belongs to the field of physical and chemical testing, and in particular relates to the detection of P91 and P92 steel original austenite grain boundaries. Background technique [0002] P91 and P92 steels have excellent high-temperature performance and are widely used in super (super) critical boiler production. Since the actual austenite grain size of the steel directly affects the properties of the steel, the coarse austenite grains often lead to the coarse structure of the material after cooling, so that the material has lower plasticity and toughness. For this reason, strengthening the inspection of the actual austenite grain size of P91 and P92 steel has always been an important indicator for boiler manufacturers to evaluate the quality of such materials. It is of great significance to study the effect of grain size on performance. [0003] In view of the large influence of the prior austenite grain size on the performance of P91 a...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): G01N15/02G01N1/32
Inventor 曾辉高淼淼
Owner DONGFANG BOILER GROUP OF DONGFANG ELECTRIC CORP
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