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Metallographic corrosive for super austenitic stainless steel and corrosion method

An austenitic stainless steel, metallographic corrosion technology, applied in the field of metallographic structure analysis, can solve the problems of easy scratching of the sample surface, difficult to handle, over-corrosion corrosion, etc., to promote timely separation from the sample surface, accurate voltage and corrosion resistance. Corrosion time, the effect of accelerating metallographic corrosion rate

Active Publication Date: 2018-05-04
NORTHEASTERN UNIV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0004] Due to the excellent corrosion resistance of super austenitic stainless steel, traditional stainless steel corrosive agents cannot reveal its metallographic structure, and strong corrosive agents such as aqua regia are prone to problems such as over-corrosion and uneven corrosion.
And there are many deficiencies in the existing stainless steel metallographic etchant and corrosion method: the composition of the corrosion solution is complex, the preparation steps are cumbersome, the stability is poor, and it cannot be reused; some corrosion solutions contain strong corrosive substances such as hydrofluoric acid, perchloric acid or aqua regia. Or harmful to the human body, there are potential safety hazards, and it is easy to pollute the environment, and it is difficult to dispose of after use; the corrosion reaction is severe, difficult to control, and the metallographic structure is not uniformly corroded; the corrosion time is long, and wiping and other methods are easy to scratch the surface of the sample. cumbersome and inefficient
Most importantly, for the same steel type, there is currently no corrosive agent that can simultaneously obtain the metallographic structure of its cast state, hot-worked state, solid solution state, aging state, and welded state. Experimental research and continuous system exploration are time-consuming, labor-intensive, and costly

Method used

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  • Metallographic corrosive for super austenitic stainless steel and corrosion method
  • Metallographic corrosive for super austenitic stainless steel and corrosion method
  • Metallographic corrosive for super austenitic stainless steel and corrosion method

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0060] (1) Corrosive preparation

[0061] At room temperature, add 6g of oxalic acid, 30mL of deionized water and 120mL of concentrated hydrochloric acid (38%) into the beaker successively, stir continuously with a glass rod, and let it stand for 1.5h after the oxalic acid is completely dissolved.

[0062] (2) Metallographic sample preparation

[0063] Cut the sample to be tested with a size of 10mm×10mm×5mm from the super austenitic stainless steel 654SMO ingot, mount the sample with a sample mounting machine, and use 120 mesh, 240 mesh, 400 mesh, 800 mesh, 1200 mesh, 1500 mesh in sequence Roughly grind and finely grind the inlaid sample with 2000-mesh water sandpaper, and then polish the sample with 3.5 μm and 2.5 μm polishing paste in turn, until the surface of the sample is bright without any scratches, pits, or stains After waiting for defects, wash with absolute ethanol and blow dry.

[0064] (3) metallographic corrosion

[0065] A, do anode with the sample after step...

Embodiment 2

[0080] (1) Corrosive preparation

[0081] At room temperature, add 10g of oxalic acid, 10mL of deionized water and 150mL of concentrated hydrochloric acid (38%) into the beaker successively, stir continuously with a glass rod, and let it stand for 2 hours after the oxalic acid is completely dissolved.

[0082] (2) Metallographic sample preparation

[0083] Homogenize the super austenitic stainless steel 654SMO ingot at 1280°C for 20 hours, cut out a sample to be tested with a size of 10mm×10mm×5mm on the ingot, mount the sample with a sample mounting machine, and sequentially use 120 mesh and 240 mesh , 400 mesh, 800 mesh, 1200 mesh, 1500 mesh and 2000 mesh water sandpaper to coarsely grind and finely grind the inlaid sample, and then polish the sample with 3.5μm and 2.5μm polishing paste in turn. After the surface is bright without any scratches, pits, stains and other defects, clean it with absolute ethanol and dry it.

[0084] (3) metallographic corrosion

[0085] A, do ...

Embodiment 3

[0100] (1) Corrosive preparation

[0101]At room temperature, add 3g of oxalic acid, 40mL of deionized water and 100mL of concentrated hydrochloric acid (37%) into the beaker successively, stir continuously with a glass rod, and let it stand for 1 hour after the oxalic acid is completely dissolved.

[0102] (2) Metallographic sample preparation

[0103] The homogenized super austenitic stainless steel 654SMO ingot is hot-rolled at 1150-1250°C into a 5mm rolling plate, and a sample to be tested with a size of 10mm×10mm×5mm is cut from the rolling plate, and the sample mounting machine is used for testing. Mount the sample, use 120 mesh, 240 mesh, 400 mesh, 800 mesh, 1200 mesh, 1500 mesh and 2000 mesh water sandpaper to rough and finely grind the mounted sample, and then use 3.5μm and 2.5μm polishing Polish the sample with paste, and after the surface of the sample is bright without any defects such as scratches, pits, stains, etc., clean it with absolute ethanol and dry it. A...

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Abstract

The invention relates to a metallographic corrosive for super austenitic stainless steel and a corrosion method. The corrosive is prepared from the following components: 2-10 weight parts of oxalic acid, 80-150 volume parts of concentrated hydrochloric acid and 0-50 volume parts of deionized water. The corrosion method comprises the following steps: S1, uniformly adding oxalic acid, deionized water and concentrated hydrochloric acid according to a ratio, uniformly stirring, and standing for an hour or longer; S2, preparing a metallographic specimen; and S3, taking the metallographic specimen as an anode, taking a highly corrosive metal material as a cathode, immersing into a corrosive, electrifying and corroding; and immediately taking out and cleaning the metal material after corrosion completion, and blowing. The corrosive disclosed by the invention is simple in composition, easy to prepare and recover, safe, environmental-friendly, capable of being repeatedly utilized and cost-saving; the corrosion method is easy to operate, accurately controllable, stable, high-efficiency and excellent in reproducibility; and the corroded specimen is clean, neat, clear and uniform in metallographic structure and excellent in corrosive effect. The metallographic corrosive disclosed by the invention is applicable to metallurgical structure analysis of multiple states such as various super austenitic stainless steel cast conditions, hot working, ageing, heat treatment, welded and the like, a one-dosage multi-purpose effect is achieved, and time and labor can be saved.

Description

technical field [0001] The invention belongs to the technical field of metallographic structure analysis, and in particular relates to a metallographic etchant and a corrosion method for super austenitic stainless steel. Background technique [0002] Super austenitic stainless steel is an austenitic alloy with significantly higher alloy content than ordinary austenitic stainless steel. It has excellent corrosion resistance and good comprehensive mechanical properties. It is widely used in petrochemical, flue gas desulfurization, and waste incineration. and seawater desalination. However, the high alloy content makes this type of steel very easy to segregate and precipitate during solidification, forming obvious dendrite structure and a large number of precipitated phases; it is very easy to crack during hot processing such as forging and rolling, especially the edge cracking is very serious . Therefore, the ingot or slab needs to be homogenized at high temperature before h...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): G01N1/32
CPCG01N1/32
Inventor 张树才李花兵姜周华张彬彬范思鹏冯浩常朋飞李志兴吴敬玺党乾
Owner NORTHEASTERN UNIV
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