Disclosure of Invention
The invention aims to provide a corrosive agent for displaying austenite grain boundaries of martensitic stainless steel and a display method, the corrosion operation is simple and convenient, the grain boundary display effect is clear, and the problems that low-carbon high-alloy steel does not have a proper corrosive agent and the corrosion method is unreasonable are solved.
The purpose of the invention can be realized by the following technical scheme:
the corrosive agent comprises potassium permanganate, concentrated sulfuric acid and water, wherein the dosage ratio of the potassium permanganate to the concentrated sulfuric acid to the water is (0.5-2) g, (5-15) mL, (85-95) mL.
Further, in the concentrated sulfuric acid, H2SO4The mass percentage of the components is 97-99%.
A preparation method of a corrosive agent for displaying austenite grain boundary of martensitic stainless steel comprises the following steps: and (3) adding concentrated sulfuric acid into water under the stirring state, then adding potassium permanganate, and uniformly stirring to obtain the corrosive agent.
An application of corrosive in displaying austenite grain boundary of martensitic stainless steel.
The method is based on the corrosive and mainly comprises preparation of a metallographic sample, ultrasonic corrosion of a sample, sample observation and grain size statistics. The method comprises the following steps:
1) carrying out austenitizing heat treatment on a martensitic stainless steel sample, polishing and polishing the quenched martensitic stainless steel sample until the surface is bright and has no scratch, and then washing and drying the martensitic stainless steel sample to obtain a sample to be corroded;
2) heating the corrosive agent to 50-80 ℃, then placing a sample to be corroded in the corrosive agent, carrying out ultrasonic vibration corrosion for 10-30 minutes to obtain a corroded sample, taking out the corroded sample, washing and drying;
3) the samples were observed with a metallographic microscope. And observing the obtained sample under a metallographic microscope, clearly observing the original austenite grain boundary of the low-carbon high-alloy martensite steel, respectively shooting metallographic pictures with different magnification factors, and counting the original austenite grain diameter and grain size by using image analysis software.
Further, in the step 1), the temperature is 900-1200 ℃ in the austenitizing heat treatment process, and the time is 10 minutes-6 hours. The quenched low-carbon high-alloy martensitic stainless steel sample can be obtained by adopting a conventional austenitizing heat treatment process.
Further, in the step 1), the grinding comprises coarse grinding and fine grinding which are sequentially carried out; the coarse grinding process comprises the following steps: sequentially grinding martensite stainless steel samples by 180#, 320#, and 600# abrasive paper; the fine grinding process comprises the following steps: the roughly ground martensitic stainless steel coupon was ground on 1200# sandpaper.
Further, in step 2), the polished surface of the sample to be etched is placed in the etchant upward. And (3) putting the beaker filled with the corrosive agent into an ultrasonic cleaning machine with a heating function, heating the beaker to 50-80 ℃ in a water bath, putting the polished surface of a sample to be corroded into the beaker in an upward mode after the temperature is constant, and starting an ultrasonic vibration function during corrosion.
Further, in step 2), the surface of the corroded sample is rinsed with alcohol.
Further, the martensitic stainless steel comprises the following components in percentage by weight: 0.01-0.14% of C, 9.00-16.00% of Cr, 0.80-10.10% of Ni, 0.65-1.60% of Mo, 0-0.8% of Si, 0-0.9% of Mn, 0-0.01% of P, 0-0.01% of S, 0-1.15% of Co, 0-0.21% of Ti, 0-1.03% of W, 0-0.20% of V, 0-0.066% of Al, 0-0.03% of Sn, 0-0.06% of N, 0-0.049% of Nb, 0-0.04% of Cu, 0-0.01% of B, and the balance of Fe and inevitable impurity elements.
Compared with the prior art, the invention has the following characteristics:
1) the corrosive disclosed by the invention needs few chemical drugs, has the advantages of safety, no toxicity, convenience in operation, good display effect and the like, and provides convenience for grading material crystal grains in the actual production process.
2) The display method can clearly display the prior austenite crystal grains of the martensitic stainless steel sample, solves the problem that the austenite crystal boundary of the martensitic stainless steel is difficult to corrode, is suitable for displaying various low-carbon high-alloy martensitic steel prior austenite boundaries which are difficult to corrode, has high success rate of corrosion of the crystal boundary of the sample, is safe and convenient for a corrosive agent and a corrosion method, effectively assists in grading of the crystal grains of the material in the actual production process, and provides a basis for optimizing a heat treatment process.
Detailed Description
The invention is described in detail below with reference to the figures and specific embodiments. The present embodiment is implemented on the premise of the technical solution of the present invention, and a detailed implementation manner and a specific operation process are given, but the scope of the present invention is not limited to the following embodiments.
Example 1:
in the embodiment, the low-carbon high-alloy steel is 0Cr16Ni5Mo1, and the specific chemical components and mass percentage content are as follows: c: 0.055%, Cr: 15.32%, Ni: 4.82%, Mo: 0.87%, Si: 0.35%, Mn: 0.88%, P: 0.005%, S: 0.002%, Sn: 0.028%, Cu: 0.04% and the balance of Fe and inevitable impurity elements.
Preparing a metallographic sample:
a. cutting a 10mm multiplied by 5mm block sample by a linear cutting method, austenitizing at 1100 ℃ for 12 minutes, and then quenching to prepare for subsequent grinding and polishing;
b. coarse grinding of the sample: grinding a sample by sequentially using silicon carbide waterproof abrasive paper with the speed of rotation of a grinding disc set to 600rpm and the next-pass abrasive paper, rotating the sample by 90 degrees along a grinding surface every time to enable a new-pass grinding mark to be vertical or approximately vertical to a previous-pass grinding mark, and grinding until the new-pass grinding mark covers the previous-pass grinding mark, wherein tap water is used as a lubricant during grinding;
c. and (3) fine grinding of the sample: grinding the rough-ground sample on 1200# silicon carbide waterproof abrasive paper, setting the rotating speed of a grinding disc at 400rpm, and grinding the sample along the direction vertical to the previous primary grinding mark until the previous primary grinding mark cannot be seen;
d. polishing of the sample: polishing the sample polished by the 1200# silicon carbide waterproof sand paper on a rough polishing cloth, sequentially using 9 mu m → 3 mu m → 0.05 mu m diamond polishing solution at the rotating speed of 200rpm to obtain a bright polished surface, sequentially washing with water and alcohol and drying by using a blower.
Preparing a corrosive agent: weighing 5mL of concentrated sulfuric acid, slowly pouring the concentrated sulfuric acid into 95mL of deionized water, continuously stirring by using a glass rod, then weighing 1.5g of potassium permanganate, pouring the potassium permanganate into a sulfuric acid solution, and fully stirring to dissolve the potassium permanganate;
③ ultrasonic corrosion of the sample: putting the beaker containing the corrosive prepared in the second step into an ultrasonic cleaning machine with a heating function, heating to 60-70 ℃, putting the sample prepared in the first step into the beaker with the polished surface facing upwards after the temperature is constant, starting ultrasonic vibration, taking out after corroding for 15-20 minutes, washing the surface of the sample with alcohol and drying;
and fourthly, observing a sample: the samples obtained through the steps from the first step to the third step are observed under a metallographic microscope with a field of view of 100 times, and as shown in figure 1, by adopting the corrosive agent and the corrosion method, the original austenite grain boundary of the 0Cr16Ni5Mo1 steel sample is complete and clearly visible, and completely meets the metallographic photograph standard required by grain size rating.
Example 2:
in the embodiment, the low-carbon high-alloy steel is X12CrMoWVNbN10-1-1, and the specific chemical components and mass percentage content are as follows: c: 0.11%, Cr: 10.35%, Ni: 0.80%, Mo: 1.00%, Si: 0.08%, Mn: 0.41%, P: 0.008%, S: 0.004%, W: 1.03%, V: 0.18%, Al: 0.02%, N: 0.05%, Nb: 0.04% and the balance of Fe and inevitable impurity elements.
Preparing a metallographic sample:
a. cutting a 10mm multiplied by 5mm block sample by a linear cutting method, austenitizing at 1150 ℃ for 30 minutes, and then quenching to prepare for subsequent grinding and polishing;
b. coarse grinding of the sample: grinding a sample by sequentially using silicon carbide waterproof abrasive paper with the speed of rotation of a grinding disc set to 600rpm and the next-pass abrasive paper, rotating the sample by 90 degrees along a grinding surface every time to enable a new-pass grinding mark to be vertical or approximately vertical to a previous-pass grinding mark, and grinding until the new-pass grinding mark covers the previous-pass grinding mark, wherein tap water is used as a lubricant during grinding;
c. and (3) fine grinding of the sample: grinding the rough-ground sample on 1200# silicon carbide waterproof abrasive paper, setting the rotating speed of a grinding disc at 400rpm, and grinding the sample along the direction vertical to the previous primary grinding mark until the previous primary grinding mark cannot be seen;
d. polishing of the sample: polishing the sample polished by the 1200# silicon carbide waterproof sand paper on a rough polishing cloth, sequentially using 9 mu m → 3 mu m → 0.05 mu m diamond polishing solution at the rotating speed of 200rpm to obtain a bright polished surface, sequentially washing with water and alcohol and drying by using a blower.
Preparing a corrosive agent: weighing 12mL of concentrated sulfuric acid, slowly pouring the concentrated sulfuric acid into 88mL of deionized water, continuously stirring by using a glass rod, then weighing 1g of potassium permanganate, pouring the potassium permanganate into a sulfuric acid solution, and fully stirring to dissolve the potassium permanganate;
③ ultrasonic corrosion of the sample: putting the beaker containing the corrosive prepared in the second step into an ultrasonic cleaning machine with a heating function, heating to 70 ℃, putting the sample prepared in the first step into the beaker with the polished surface facing upwards after the temperature is constant, starting ultrasonic vibration, taking out the sample after corroding for 20 minutes, washing the surface of the sample with alcohol and drying the sample;
and fourthly, observing a sample: observing the sample obtained through the steps from the first step to the third step under a metallographic microscope with a field of view of 100 times, and as shown in figure 2, by adopting the corrosive agent and the corrosion method, the original austenite grain boundary of the X12CrMoWVNbN10-1-1 steel sample is clear and complete, and although a little tissue appears in the inside of the grain, the grain also meets the metallographic standard required by grain size rating.
Example 3:
in the embodiment, the low-carbon high-alloy steel is COST-FB2 rotor steel, and comprises the following specific chemical components in percentage by mass: c: 0.14%, Cr: 9.06%, Co: 1.15%, Mo: 1.51%, Ni: 0.17%, Si: 0.06%, Mn: 0.42%, V: 0.20%, N: 0.06%, Nb: 0.049%, B: 0.008% and the balance of Fe and inevitable impurity elements.
Preparing a metallographic sample:
a. cutting a 10mm multiplied by 5mm massive sample by a linear cutting method, austenitizing the sample at 950 ℃ for 5 hours, and then quenching the sample to prepare for subsequent grinding and polishing;
b. coarse grinding of the sample: grinding a sample by sequentially using silicon carbide waterproof abrasive paper with the speed of rotation of a grinding disc set to 600rpm and the next-pass abrasive paper, rotating the sample by 90 degrees along a grinding surface every time to enable a new-pass grinding mark to be vertical or approximately vertical to a previous-pass grinding mark, and grinding until the new-pass grinding mark covers the previous-pass grinding mark, wherein tap water is used as a lubricant during grinding;
c. and (3) fine grinding of the sample: grinding the rough-ground sample on 1200# silicon carbide waterproof abrasive paper, setting the rotating speed of a grinding disc at 400rpm, and grinding the sample along the direction vertical to the previous primary grinding mark until the previous primary grinding mark cannot be seen;
d. polishing of the sample: polishing the sample polished by the 1200# silicon carbide waterproof sand paper on a rough polishing cloth, sequentially using 9 mu m → 3 mu m → 0.05 mu m diamond polishing solution at the rotating speed of 200rpm to obtain a bright polished surface, sequentially washing with water and alcohol and drying by using a blower.
Preparing a corrosive agent: weighing 13mL of concentrated sulfuric acid, slowly pouring the concentrated sulfuric acid into 87mL of deionized water, continuously stirring by using a glass rod, then weighing 1.2g of potassium permanganate, pouring the potassium permanganate into a sulfuric acid solution, and fully stirring to dissolve the potassium permanganate;
③ ultrasonic corrosion of the sample: putting the beaker containing the corrosive prepared by the second step into an ultrasonic cleaning machine with a heating function, heating to 65 ℃, putting the sample prepared by the first step into the beaker with the polished surface facing upwards after the temperature is constant, starting ultrasonic vibration, taking out the sample after corroding for 22 minutes, washing the surface of the sample by alcohol and drying the sample;
and fourthly, observing a sample: the samples obtained through the steps from the first step to the third step are observed under a metallographic microscope with a field of view of 100 times, and as shown in figure 3, by adopting the corrosive and the corrosion method, the prior austenite grain boundary of the COST-FB2 rotor steel sample is clear and complete and meets the metallographic photograph standard required by grain size rating.
Example 4:
in the embodiment, the low-carbon high-alloy steel is 00Cr12Ni10MoTi steel, and the specific chemical components and mass percentage content are as follows: c: 0.017%, Cr: 11.88%, Ni: 10.1%, Mo: 0.65%, Ti: 0.21%, Si: 0.78%, Mn: 0.0075%, Al: 0.066%, S: 0.001%, P: 0.004%, and the balance of Fe and inevitable impurity elements.
Preparing a metallographic sample:
a. cutting a 10mm multiplied by 5mm block sample by a linear cutting method, austenitizing at 1100 ℃ for 1 hour, and then quenching to prepare for subsequent grinding and polishing;
b. coarse grinding of the sample: grinding a sample by sequentially using silicon carbide waterproof abrasive paper with the speed of rotation of a grinding disc set to 600rpm and the next-pass abrasive paper, rotating the sample by 90 degrees along a grinding surface every time to enable a new-pass grinding mark to be vertical or approximately vertical to a previous-pass grinding mark, and grinding until the new-pass grinding mark covers the previous-pass grinding mark, wherein tap water is used as a lubricant during grinding;
c. and (3) fine grinding of the sample: grinding the rough-ground sample on 1200# silicon carbide waterproof abrasive paper, setting the rotating speed of a grinding disc at 400rpm, and grinding the sample along the direction vertical to the previous primary grinding mark until the previous primary grinding mark cannot be seen;
d. polishing of the sample: polishing the sample polished by the 1200# silicon carbide waterproof sand paper on a rough polishing cloth, sequentially using 9 mu m → 3 mu m → 0.05 mu m diamond polishing solution at the rotating speed of 200rpm to obtain a bright polished surface, sequentially washing with water and alcohol and drying by using a blower.
Preparing a corrosive agent: weighing 15mL of concentrated sulfuric acid, slowly pouring the concentrated sulfuric acid into 85mL of deionized water, continuously stirring by using a glass rod, then weighing 0.8g of potassium permanganate, pouring the potassium permanganate into a sulfuric acid solution, and fully stirring to dissolve the potassium permanganate;
③ ultrasonic corrosion of the sample: putting the beaker containing the corrosive prepared in the second step into an ultrasonic cleaning machine with a heating function, heating to 75 ℃, putting the sample prepared in the first step into the beaker with the polished surface facing upwards after the temperature is constant, starting ultrasonic vibration, taking out the sample after corroding for 18 minutes, washing the surface of the sample with alcohol and drying the sample;
and fourthly, observing a sample: the samples obtained through the steps from the first step to the third step are observed under a metallographic microscope with a field of view of 100 times, and as shown in figure 4, by adopting the corrosive agent and the corrosion method, the original austenite grain boundary of the 00Cr12Ni10MoTi steel sample is clear and complete and completely meets the metallographic photograph standard required by grain size rating.
Example 5:
the corrosive agent comprises potassium permanganate, concentrated sulfuric acid and water, wherein the dosage ratio of the potassium permanganate to the concentrated sulfuric acid to the water is 0.5g to 15mL to 85 mL.
In concentrated sulfuric acid, H2SO4The mass percentage of (B) is 99%.
The preparation method of the corrosive comprises the following steps: and (3) adding concentrated sulfuric acid into water under the stirring state, then adding potassium permanganate, and uniformly stirring to obtain the corrosive agent.
A method for displaying austenite grain boundary of martensitic stainless steel is based on the corrosive agent and comprises the following steps:
1) carrying out austenitizing heat treatment on a martensitic stainless steel sample, grinding and polishing after quenching, and then washing and drying to obtain a sample to be corroded;
2) heating the corrosive agent to 80 ℃, then placing a sample to be corroded in the corrosive agent, carrying out ultrasonic vibration corrosion for 10 minutes to obtain a corroded sample, taking out the corroded sample, washing and drying;
3) the samples were observed with a metallographic microscope.
In the step 1), the temperature is 1200 ℃ and the time is 10 minutes in the austenitizing heat treatment process. The polishing comprises coarse grinding and fine grinding which are sequentially carried out; the coarse grinding process comprises the following steps: sequentially grinding martensite stainless steel samples by 180#, 320#, and 600# abrasive paper; the fine grinding process comprises the following steps: the roughly ground martensitic stainless steel coupon was ground on 1200# sandpaper.
In step 2), the polished surface of the sample to be corroded is placed upwards in the corrosive agent. The surface of the corroded sample is rinsed with alcohol.
Example 6:
the corrosive agent comprises potassium permanganate, concentrated sulfuric acid and water, wherein the dosage ratio of the potassium permanganate to the concentrated sulfuric acid to the water is 2g:5mL:95 mL.
In concentrated sulfuric acid, H2SO4The mass percentage of (B) is 98%.
The preparation method of the corrosive comprises the following steps: and (3) adding concentrated sulfuric acid into water under the stirring state, then adding potassium permanganate, and uniformly stirring to obtain the corrosive agent.
A method for displaying austenite grain boundary of martensitic stainless steel is based on the corrosive agent and comprises the following steps:
1) carrying out austenitizing heat treatment on a martensitic stainless steel sample, grinding and polishing after quenching, and then washing and drying to obtain a sample to be corroded;
2) heating the corrosive agent to 50 ℃, then placing a sample to be corroded in the corrosive agent, carrying out ultrasonic vibration corrosion for 30 minutes to obtain a corroded sample, taking out the corroded sample, washing and drying;
3) the samples were observed with a metallographic microscope.
In the step 1), the temperature is 900 ℃ and the time is 6 hours in the austenitizing heat treatment process. The polishing comprises coarse grinding and fine grinding which are sequentially carried out; the coarse grinding process comprises the following steps: sequentially grinding martensite stainless steel samples by 180#, 320#, and 600# abrasive paper; the fine grinding process comprises the following steps: the roughly ground martensitic stainless steel coupon was ground on 1200# sandpaper.
In step 2), the polished surface of the sample to be corroded is placed upwards in the corrosive agent. The surface of the corroded sample is rinsed with alcohol.
Example 7:
the corrosive agent comprises potassium permanganate, concentrated sulfuric acid and water, wherein the dosage ratio of the potassium permanganate to the concentrated sulfuric acid to the water is 1g:10mL:90 mL.
In concentrated sulfuric acid, H2SO4The mass percentage of (B) is 97%.
The preparation method of the corrosive comprises the following steps: and (3) adding concentrated sulfuric acid into water under the stirring state, then adding potassium permanganate, and uniformly stirring to obtain the corrosive agent.
A method for displaying austenite grain boundary of martensitic stainless steel is based on the corrosive agent and comprises the following steps:
1) carrying out austenitizing heat treatment on a martensitic stainless steel sample, grinding and polishing after quenching, and then washing and drying to obtain a sample to be corroded;
2) heating the corrosive agent to 60 ℃, then placing a sample to be corroded in the corrosive agent, carrying out ultrasonic vibration corrosion for 20 minutes to obtain a corroded sample, taking out the corroded sample, washing and drying;
3) the samples were observed with a metallographic microscope.
In the step 1), the temperature is 1100 ℃ and the time is 2 hours in the austenitizing heat treatment process. The polishing comprises coarse grinding and fine grinding which are sequentially carried out; the coarse grinding process comprises the following steps: sequentially grinding martensite stainless steel samples by 180#, 320#, and 600# abrasive paper; the fine grinding process comprises the following steps: the roughly ground martensitic stainless steel coupon was ground on 1200# sandpaper.
In step 2), the polished surface of the sample to be corroded is placed upwards in the corrosive agent. The surface of the corroded sample is rinsed with alcohol.
The embodiments described above are described to facilitate an understanding and use of the invention by those skilled in the art. It will be readily apparent to those skilled in the art that various modifications to these embodiments may be made, and the generic principles described herein may be applied to other embodiments without the use of the inventive faculty. Therefore, the present invention is not limited to the above embodiments, and those skilled in the art should make improvements and modifications within the scope of the present invention based on the disclosure of the present invention.