CN-121992408-A - Metallographic corrosive liquid for 4Cr13 stainless steel and corrosion method for displaying carbide

Abstract

The invention belongs to the technical field of martensitic stainless steel performance detection, and relates to a 4Cr13 stainless steel metallographic corrosive liquid and a corrosion method for displaying carbide. Glacial acetic acid is organic weak acid, is more environment-friendly and mild than inorganic acid, can reduce overcorrosion of grain boundaries, and ammonium persulfate is a mild oxidant, releases active oxygen in an acidic environment, selectively damages a passivation film, enhances corrosion of the grain boundaries and phase boundaries, and avoids using strong acid or heavy metal. MoO 2 /MoO 3 nanometer film is generated by adsorbing molybdate ions in sodium molybdate on the surface of carbide, blue-black contrast is generated by optical interference, the contrast of the carbide is obviously improved, and toxic picric acid is replaced. The absolute ethyl alcohol is an environment-friendly organic solvent, so that the reaction rate is reduced, the uniformity is improved, and the environment is friendly.

Inventors

• HOU TING
• GUI WEIMIN
• JIANG JINHANG
• HE LIANGLIANG
• LEI XIAOJUAN
• LI LI
• DONG YANG
• ZHANG XIAOTIAN

Assignees

• 陕西法士特汽车传动集团有限责任公司

Dates

Publication Date

20260508

Application Date

20260202

Claims (8)

1. 1. The metallographic etching solution for 4Cr13 stainless steel is characterized by being used for etching 4Cr13 stainless steel and comprising the following components of 10-15 mL of glacial acetic acid, 1-2 g of ammonium persulfate, 0.5-1 g of sodium molybdate, 70-80 mL of absolute ethyl alcohol and 10-15 mL of deionized water.
2. 2. The martensitic stainless steel metallographic etching solution according to claim 1, wherein the etching solution is prepared from the following components of 10mL of glacial acetic acid, 1 g-1.5 g of ammonium persulfate, 0.5 g-0.8 g of sodium molybdate, 80mL of absolute ethyl alcohol and 10mL of deionized water.
3. 3. The 4Cr13 stainless steel metallographic etchant according to claim 1, wherein the etchant is prepared from 10mL glacial acetic acid, 1.5g ammonium persulfate, 0.5g sodium molybdate, 80mL absolute ethanol and 10mL deionized water.
4. 4. The method for preparing the 4Cr13 stainless steel metallographic corrosive liquid according to claim 1, comprising the following steps: dissolving ammonium persulfate and sodium molybdate in deionized water, and stirring until the ammonium persulfate and the sodium molybdate are completely dissolved to obtain a solution A; Mixing glacial acetic acid with absolute ethyl alcohol to obtain a solution B; pouring the solution A into the solution B, stirring until the mixed solution is transparent, and sealing and keeping the mixed solution away from light to obtain corrosive liquid; the mass ratio of ammonium persulfate to sodium molybdate is 1-2:0.5-1, and the volume ratio of glacial acetic acid to absolute ethyl alcohol to deionized water is 1-1.5:7-8:1-1.5.
5. 5. The method for etching 4Cr13 stainless steel metallographic etchant displaying carbide according to claim 1, comprising the steps of: 4Cr13 stainless steel is subjected to polishing pretreatment for standby; preparing a corrosive liquid; And (3) completely immersing the standby 4Cr13 stainless steel into corrosive liquid, placing the polished mirror surface of the 4Cr13 stainless steel upwards, corroding at the temperature of 40-50 ℃ for 10-20 min, taking out the sample after the corrosion surface is observed to turn yellow, flushing with absolute ethyl alcohol, and drying.
6. 6. The method of claim 5, wherein the heating temperature is 50 ℃ and the etching time period is 15 minutes.
7. 7. The method for indicating carbide according to claim 5, wherein the step of polishing 4Cr13 stainless steel comprises the steps of wire cutting a 4Cr13 stainless steel test block, grinding, coarse grinding with metallographic sand paper, fine grinding to a polished mirror surface state, washing, and drying.
8. 8. The method of claim 5, wherein the 4Cr13 stainless steel comprises, by mass, 0.36% -0.45% of C, 12.00% -14.00% of Cr, 0.60% or less of Si, 0.80% or less of Mn, 0.040% or less of P, 0.030% or less of S, 0.60% or less of Ni, and the balance of Fe and unavoidable impurities.

Description

Metallographic corrosive liquid for 4Cr13 stainless steel and corrosion method for displaying carbide Technical Field The invention belongs to the technical field of martensitic stainless steel performance detection, and particularly relates to a 4Cr13 stainless steel metallographic corrosive liquid and a corrosion method for displaying carbide. Background Martensitic stainless steel is widely used in industrial fields such as structural members of gears and bearings, automobile components, hot-working dies, turbine blades, petroleum and natural gas valves, cutting tools, medical instruments and the like because of its excellent mechanical properties, good wear resistance and corrosion resistance. Metallographic structure is an analysis means which cannot be replaced for evaluating material performance, and corrosive agent is a key for obtaining clear metallographic structure. The conventional martensitic stainless steel corrosive agent mainly comprises four kinds of high ferric chloride+hydrochloric acid aqueous solution, nitrate acid aqueous solution, picric acid+hydrochloric acid+alcohol solution and aqua regia glycerol. Tissue is distinguished primarily by changing the surface contrast of the material. The core defects and pain points are that 1, the corrosion time is difficult to control, because when FeCl 3 is corroded, sulfur-oxygen composite inclusions in a sample matrix fall off under the corrosion of Cl -1 to form micropores, and the micropores expand along with the prolongation of the corrosion time, so that a large number of black points appear on the sample surface, a inspector is misled, the difficulty of analysis is increased, heavy metals are required to be recovered, and the waste liquid treatment is complex. 2. The reagent is difficult to obtain, namely, concentrated nitric acid belongs to the controlled reagent and is difficult to purchase. Picric acid has excellent identification effect on carbide, but is extremely toxic and easy to explode, so the picric acid cannot be purchased at present. 3. There is a great potential safety hazard, picric acid is extremely toxic, a small amount of mistaking or inhaling can cause death, and gastroenteritis, hemorrhagic nephritis and acute hepatitis can be caused when the picric acid is extremely trace. Picric acid is prone to severe explosion during friction and vibration. Concentrated sulfuric acid, nitric acid, hydrochloric acid and the like have extremely strong corrosiveness, and have great potential safety hazards during use. 4. Metallographic structures are difficult to distinguish, a plurality of structures appear simultaneously after corrosion, but the interlining degree of the structures is not obvious, and the difficulty exists in observing a certain specific structure. For example, the wear resistance of martensitic stainless steel mainly depends on the form and distribution of carbide in the structure, and the metallographic structure needs to pay extra attention to the form and distribution of the carbide in the structure when being observed, so that an environment-friendly and easily-obtained corrosive liquid capable of obviously identifying carbide in 4Cr13 stainless steel is urgently needed. Disclosure of Invention Aiming at the defects of the prior art, the invention aims to provide a 4Cr13 stainless steel metallographic corrosive liquid and a carbide displaying corrosion method, wherein the corrosive liquid is a corrosive liquid without picric acid, heavy metal and strong inorganic acid, can be used for displaying carbide and realizes the directional identification of carbide structures in martensitic stainless steel. In order to solve the technical problems, the invention provides a 4Cr13 stainless steel metallographic etching solution which is prepared from the following components of 10mL glacial acetic acid, 1 g-2 g ammonium persulfate, 0.5 g-1 g sodium molybdate, 80mL absolute ethyl alcohol and 10mL deionized water. Preferably, the corrosive liquid is prepared from the following components of 10mL of glacial acetic acid, 1 g-1.5 g of ammonium persulfate, 0.5 g-0.8 g of sodium molybdate, 80mL of absolute ethyl alcohol and 10mL of deionized water. Preferably, the etching solution is prepared from 10mL of glacial acetic acid, 1.5g of ammonium persulfate, 0.5g of sodium molybdate, 80mL of absolute ethanol and 10mL of deionized water. Preferably, the martensitic stainless steel subjected to metallographic detection by the corrosive liquid is 4Cr13 stainless steel. The invention provides a preparation method of corrosive liquid for martensite stainless steel metallographic detection, which comprises the following steps: dissolving ammonium persulfate and sodium molybdate in deionized water, and stirring until the ammonium persulfate and the sodium molybdate are completely dissolved to obtain a solution A; Mixing glacial acetic acid with absolute ethyl alcohol to obtain a solution B; pouring the solution A into the solution B, stirring