Austenitic stainless steel metallography corrosion agent and austenitic stainless steel metallography display method

Abstract

The invention provides an austenitic stainless steel metallography corrosion agent with good erosion effect, and an austenitic stainless steel metallography display method. The corrosion agent has the advantages of simple preparation, convenient operation and small pollution, and the display method had the advantages of good stability and reappearance, and rapid, uniform and clear display of the microstructure. The display method comprises the following steps: mixing 1 part by volume of nitric acid with the mass concentration of 65-68% with 3 parts by volume of hydrochloric acid with the mass concentration of 36-38%, 1.5-3 parts by volume of acetic acid with the mass concentration of 36% and 1 part by volume of hydrofluoric acid with the mass concentration of 40% or more, slightly stirring by using a stirring bar for 20s, standing for 30min to prepare the corrosion agent; immersing a polished austenitic stainless steel sample in the corrosion agent, making the corrosion surface of the sample vertical to the surface of the corrosion agent during immersion, slightly stirring the sample, and allowing the sample to be immersed for 35-60s until the corrosion surface is argenteous; and taking out the immersed sample, flushing by using clear water, carrying out spray washing by using anhydrous ethanol, and carrying out blow drying to obtain the austenitic stainless steel structure to be observed.

Description

technical field [0001] The invention relates to an etchant and a display method for the metallographic phase of austenitic stainless steel, which is especially suitable for 316 and 316L austenitic stainless steel. Background technique [0002] Austenitic stainless steel is the most important type in the stainless steel family. It is widely used in various industrial fields and daily consumer fields due to its corrosion resistance, good room temperature and low temperature plastic toughness, easy formability and good weldability. The output of austenitic stainless steel accounts for 70% of the output of stainless steel, and its products cover almost all types of metallurgical products such as plates, tubes, wires, strips, rods and forgings. [0003] In the research of austenitic stainless steel, its composition and processing heat treatment process determine its structure type, and then determine its performance. In order to obtain the required austenitic stainless steel, it...

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Problems solved by technology

[0004] According to the current published literature and patents, there are usually more or less problems in the following aspects of 316L austenitic stainless steel corrosives: 1. The reaction is violent, the corrosion time is not easy to control, and the structure is not uniformly corroded; 2. The stability of the corrosive agent is poor , the reproducibility is not good; 3. The preparation or operation is more complicated; 4. The grain size rating of twin interference in the structure, especially when used for the cut point method rating and metallographic software rating, has a greater impact on the results

For example, the invention patent with the publication number CN102517585A is a corrosive agent composed of hydrochloric acid, glycerin, nitric acid and hydrogen peroxide. Although it meets the purpose of displaying tissue, it has some shortcomings: its component hydrogen peroxide is a strong oxidant, and it needs to be prepared now. For use, the etchant has poor stability and cannot be stored for a long time; the corrosion time is long, ranging from a few minutes to tens of minutes; there are many twine crystals in the metallographic structure after corrosion, which interferes with the grain size rating

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