Display method of metallographic structure of austenitic and ferritic dissimilar steel joints

Abstract

The invention discloses a display method for a metallographic structure of an austenite and ferrite dissimilar steel joint. According to the display method, the operation is simple, rapid and safe, and an etching process is easy to control. The display method comprises steps as follows: (1), sampling: sampling is performed at the austenite and ferrite dissimilar steel joint; (2), preparation of etching solutions: the etching solutions comprise an electrolysis etching solution, an intermediate treatment etching solution and a chemical etching solution; (3), etching treatment of a dissimilar steel joint sample: a to-be-detected sample is clipped by a pair of anodic stainless steel tweezers and soaked into the electrolysis etching solution, the distance between an analysis surface of the to-be-detected sample and a cathode is enabled to be 5-20 mm, and the to-be-detected sample is etched for 2-10 s; the sample is soaked into the intermediate treatment etching solution, and the surface is wiped for 2-10 s; then the sample is soaked into the chemical etching solution and wiped until the surface is silver gray; finally, the sample is washed with clean water, absolute ethyl alcohol is dropwise added to the sample, and the sample is blow-dried by a blower; (4), the sample is subjected to microexamination. The display method is simple to operate, convenient and rapid to use, good in repeatability and suitable for daily batch inspection and has great guiding significance for production.

Description

Technical field [0001] The invention relates to a physical and chemical inspection method, especially a method for displaying the metallographic structure of dissimilar steel joints. Background technique [0002] my country is an energy country dominated by coal. Thermal power generation still occupies a dominant position in the entire power production and remains the most important source of electricity at present and for a long time to come. At present, the main way to improve the efficiency of thermal power generation in various countries in the world is to increase steam parameters, that is, to increase the steam pressure and temperature entering the steam turbine. Therefore, super (super) critical thermal power generating units have been vigorously developed. [0003] With the improvement of thermal power generation unit parameters, the steel grades used in power station boilers have also changed from carbon steel to pearlite, bainite, martensite and even austenitic hea...

AI Technical Summary

Problems solved by technology

These factors make the electrochemical properties of dissimilar steel joints different in different regions, and the display method becomes more complicated and difficult compared with the same steel.

[0004] At present, for dissimilar steel welded joints, especially dissimilar steel joints composed of austenite and ferrite, it is difficult to find a single etchant that can clearly display the microstructure of each area of ​​the joint at the same time

This is mainly because the stainless steel etchant prepared according to the traditional ratio is some strong acid etchant. For ferritic steel, the etching speed is too fast, and the degree of etching is difficult to control, which can easily lead to the occurrence of corrosion on the ferrite side. Corrosion phenomenon

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