CN110823888A - Method for measuring sorbitizing rate of medium-high carbon steel wire rod - Google Patents
Method for measuring sorbitizing rate of medium-high carbon steel wire rod Download PDFInfo
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Abstract
The invention discloses a method for determining the sorbite rate of a medium-high carbon steel wire rod, which comprises the steps of intercepting a cross section sample of the medium-high carbon steel wire rod, taking any point on the cross section sample of the medium-high carbon steel wire rod as a detection point, continuously shooting a plurality of metallographic pictures on the detection point, separating a white area and a green area in each metallographic picture according to a set gray value, determining ferrite, pearlite and a sorbite structure area in each metallographic picture according to the sorbite rate which is the area of the sorbite structure area/the area of the whole structure area (the area of the sorbite structure area + the area of the ferrite area + the area of the pearlite structure area), calculating the sorbite rate of each metallographic picture, and taking the average value of the sorbite rate as the sorbite rate of the cross section sample of the medium-high carbon steel wire rod; the method solves the problems of large error and long time consumption of the existing sorbitizing rate measurement, can accurately measure the sorbitizing rate of the medium-high carbon steel wire rod, and has simple process and easy operation.
Description
Technical Field
The invention belongs to the technical field of metallographic determination, and particularly relates to a method for determining sorbite rate of medium-high carbon steel wire rods.
Background
Sorbite is a mixture of ferrite and cementite, but much finer than the lamellar spacing of pearlite, also called fine pearlite. With the development of medium-high carbon steel wire rod products with different brands and specifications at home and abroad, the product quality inspection is that besides the conventional mechanical property, the sorbitizing rate is an important quality index of the medium-high carbon steel wire rod, for the medium-high carbon steel wire rod, the sorbitizing rate is a tissue with both strong toughness and best comprehensive mechanical property in steel tissues, and the higher sorbitizing rate can ensure that the strength and plasticity index of the wire rod are greatly improved, and the wire rod is uniformly deformed and is not easy to break particularly in the drawing process. Therefore, an accurate determination of the sorbitizing rate must be ensured during the test analysis.
At present, there are no more than two methods for measuring sorbite rate in the industry: 1. judging pearlite and sorbite tissues by judging whether the lamellar structure can be seen clearly under an optical microscope by 500 times; 2. and directly measuring the inter-lamellar spacing under a scanning electron microscope for identification. The two methods have respective advantages and disadvantages, the first method has high measuring speed but larger error in accuracy, and the second method can accurately measure but takes longer time and is not suitable for production inspection.
Disclosure of Invention
The invention aims to provide a method for measuring the sorbite rate of a medium-high carbon steel wire rod, which solves the problems of large error and long time consumption of the conventional sorbite rate measurement.
The method comprises the steps of intercepting a cross section sample of the medium-high carbon steel wire rod, taking any point on the cross section sample of the medium-high carbon steel wire rod as a detection point, continuously shooting a plurality of metallographs on the detection point, separating a white area and a green area in each metallograph according to a set gray value, determining ferrite, pearlite and a sorbite structure area in each metallograph, calculating the sorbite rate of each metallograph according to the sorbite rate which is the area of the sorbite structure area/the area of the whole structure area, and taking the average value of the sorbite rate as the sorbite rate of the cross section sample of the medium-high carbon steel wire rod.
The invention is also characterized by comprising the following steps:
step 1, cutting a sample of the cross section of a medium-high carbon steel wire rod, inlaying and polishing the sample, corroding the sample by a nitric acid alcohol solution, and drying the sample;
step 2, taking any point on the circumference of a quarter diameter position away from the center of the circle of the cross section sample of the medium-high carbon steel wire rod processed in the step 1 as a detection point, and continuously shooting a plurality of metallographic pictures on the detection point;
step 3, setting an initial gray value A, separating a white area and a green area of each metallographic picture shot in the step 2 according to the set gray value, if the initial gray value A cannot separate the white area and the green area of the metallographic picture, adjusting the gray value, stopping adjusting when the white area and the green area can be separated, and obtaining a gray value B of each metallographic picture;
step 4, manually separating the pearlite structure with larger lamellar spacing of each metallographic picture shot in the step 2 to serve as a white area, and separating according to the gray value B obtained in the step 3 and the fact that the ferrite structure is a white area and the sorbite structure is a green area, so that the ferrite, pearlite and sorbite structure areas in each metallographic picture are determined;
and 5, calculating the sorbing rate of each metallographic photograph according to the areas of the ferrite, the pearlite and the sorbing structure regions determined in the step 4 and the sorbing rate of each metallographic photograph, wherein the sorbing rate is the sorbing rate of the cross section sample of the medium-high carbon steel wire rod.
In the step 2, the equipment for shooting the metallographic picture adopts an optical microscope with a shooting function.
In the step 2, the shot metallographic picture is obtained by the detection point under the field of view with the magnification of 500 times.
The pearlite structure with a large lamellar spacing is a lamellar pearlite structure which can be observed under a magnification of 500 times for each metallographic photograph.
The method for measuring the sorbite rate of the medium-high carbon steel wire rod has the advantages that after the gray value B is determined, ferrite, pearlite and sorbite can be rapidly and accurately separated, so that the sorbite is measured, the sorbite rate of the sorbite is calculated, the measuring method is simple and high in accuracy, the product quality of the medium-high carbon steel wire rod is guaranteed, and the method is beneficial to inspection and analysis of medium-high carbon steel wire rod products in the production process.
Drawings
FIG. 1 is a first metallographic photograph taken by a method for determining the sorbite ratio of a medium-high carbon steel wire rod according to the invention;
FIG. 2 is a second metallographic photograph taken by the method for determining the sorbite ratio of the medium-high carbon steel wire rod according to the invention;
FIG. 3 is a third metallographic photograph taken by the sorbite ratio determination method for medium-high carbon steel wire rods;
FIG. 4 is a metallographic photograph after determining a gray value B by a method for determining the sorbitizing rate of a medium-high carbon steel wire rod according to the invention;
FIG. 5 is a metallographic photograph of a medium-high carbon steel wire rod after separation of ferrite, pearlite and sorbite by the method for measuring the sorbite ratio of the medium-high carbon steel wire rod.
Detailed Description
The present invention will be described in further detail with reference to the accompanying drawings and specific embodiments.
The invention discloses a method for determining the sorbite rate of a medium-high carbon steel wire rod, which comprises the steps of intercepting a cross section sample of the medium-high carbon steel wire rod, taking any point on the cross section sample of the medium-high carbon steel wire rod as a detection point, continuously shooting a plurality of metallographic pictures on the detection point, separating a white structure area and a green structure area in each metallographic picture according to a set gray value, determining ferrite, pearlite and a sorbite structure area in each metallographic picture, calculating the sorbite rate of each metallographic picture according to the sorbite rate which is the area of the sorbite structure area/the area of the whole structure area (the area of the sorbite structure area, the area of the ferrite area and the area of the pearlite structure area), and taking the average value of the sorbite rates as the sorbite rate of the cross section sample of the medium-high carbon steel wire rod.
Step 1, cutting a sample of the cross section of a medium-high carbon steel wire rod, inlaying and polishing the sample, corroding the sample by a nitric acid alcohol solution, and drying the sample;
step 2, selecting a view field: taking any point on a circle with a diameter of one fourth of the circle center of the cross section sample of the medium-high carbon steel wire rod processed in the step 1 as a detection point, and continuously shooting a plurality of metallographic pictures under a view field with the magnification of 500 times on the detection point by adopting an optical microscope with a shooting function;
step 3, determining a gray value: setting an initial gray value A, separating a white tissue area and a green tissue area of each metallographic picture shot in the step 2 according to the set gray value by metallographic analysis software (specifically adopting Olympus optical microscope metallographic analysis m3 software), wherein the white tissue area and the green tissue area of the metallographic picture cannot be accurately separated by the initially set gray value A due to different corrosion time and different product influences, and if the white tissue area and the green tissue area of the metallographic picture cannot be accurately separated by the initial gray value A, manually intervening to adjust the gray value A until the white tissue area and the green tissue area can be separated, stopping adjusting, and obtaining a gray value B of each metallographic picture;
step 4, tissue separation: manually separating a lamellar pearlite structure which can be clearly seen in each metallographic picture shot in the step 2 under the condition of 500 times to obtain a white area, and separating the lamellar pearlite structure and the sorbite structure according to the gray value B obtained in the step 3, wherein the ferrite structure is the white area and the sorbite structure is the green area, so that the ferrite, the pearlite and the sorbite structure areas in each metallographic picture are determined;
if the plurality of separated metallographic photos are the same middle-high carbon steel wire rod cross section sample and are obtained by corroding the same nitric acid alcohol solution, only the gray value B of one metallographic photo is determined, and the gray value B is directly adopted by other metallographic photos so as to improve the inspection efficiency;
step 5, determining the sorbitizing rate: and (4) calculating the sorbing rate of each photo according to the areas of the ferrite, the pearlite and the sorbing structure area determined in the step (4) and the sorbing rate of each photo, namely the sorbing rate of the cross section sample of the medium-high carbon steel wire rod.
Because the pearlite structure is a mixed structure, white ferrite structure and black cementite structure in lamellar pearlite which can be observed under 500 times can be separated by the aid of olympus optical microscope metallographic analysis m3 software in the calculation process, black cementite is treated as a green area, large deviation occurs in a sorbite rate measurement result, after the gray value B is determined, manual intervention is needed to separate the integral lamellar pearlite which can be observed under 500 times as one of white areas, the structure of the sample is separated into ferrite, pearlite and sorbite, and accordingly the proportion of sorbite is accurately measured.
And (3) experimental verification:
taking a phi 8mm/65# steel wire rod, measuring the sorbitizing rate of the steel wire rod, and specifically performing the following steps:
step 1, cutting a sample of the cross section of a phi 8mm/65# steel wire rod, inlaying and polishing the sample, corroding the sample by a nitric acid alcohol solution, and drying the sample;
step 2, selecting a view field: taking any point on the circumference of a quarter diameter position away from the center of the circle of the cross section sample of the medium-high carbon steel wire rod processed in the step 1 as a detection point, continuously shooting a plurality of metallographic pictures under a view field with the magnification of 500 times on the detection point by adopting an optical microscope with a shooting function, and shooting three pictures shown in a figure 1, a figure 2 and a figure 3;
step 3, determining a gray value: setting an initial gray value A of 120 for the picture 1, separating a white area and a green area of the metallographic picture of the picture 1 shot in the step 2 by using an olympus optical microscope metallographic analysis m3 software according to the set gray value, wherein the gray value A is an obtained metallographic picture gray value B, and obtaining a picture 4 after separation;
since fig. 2 and 3 are the same etching conditions and the same product, the gray value a is set to 120;
step 4, tissue separation: manually separating the integral lamellar pearlite structure observed in the picture 4 obtained in the step 3 by 500 times to obtain a white area, and separating the white area according to the gray value A according to that the ferrite structure is a white area and the sorbite structure is a green area to obtain a ferrite, pearlite and sorbite structure area as shown in the figure 5, wherein the white area comprises ferrite and pearlite areas;
step 5, determining the sorbitizing rate: according to the areas of the ferrite, pearlite and sorbite regions determined in the step 4, the sorbite rate of the metallographic photograph in fig. 1 is calculated to be 84.66% according to the sorbite rate of the sorbite region area/the entire structure region area (the area of the sorbite region + the area of the ferrite region + the area of the pearlite region), when the gray value a is 120, the sorbite rate of fig. 2 and 3 is calculated to be 85.28% according to the steps 3 and 4, the sorbite rate of fig. 3 is calculated to be 85.74%, the average value of the sorbite rates of fig. 2, 2 and 3 is 85.23%, and therefore the sorbite rate of the phi 8mm/65# steel wire rod is 85.23%.
Through the mode, the sorbite rate measuring method for the medium-high carbon steel wire rod has the advantages that as the pearlite structure is a mixed structure, therefore, in the calculation process, metallographic analysis software can separate the white ferrite structure and the black cementite structure in pearlite with larger lamellar spacing, and the black cementite is treated as a green area, so that the sorbite rate measurement result has larger deviation, the determination method of the invention determines the gray value B through manual intervention, can quickly and accurately separate ferrite, pearlite and sorbite, thereby measuring the sorbite, calculating the sorbite rate of the sorbite, determining the sample under the same processing condition only by determining the gray value once, having simple measuring method and high accuracy, thereby ensuring the product quality of the medium and high carbon steel wire rod and being beneficial to the inspection and analysis of the medium and high carbon steel wire rod product in the production process.
Claims (5)
1. A method for determining the sorbing rate of a medium-high carbon steel wire rod is characterized by comprising the steps of intercepting a cross section sample of the medium-high carbon steel wire rod, taking any point on the cross section sample which is far away from the medium-high carbon steel wire rod as a detection point, continuously shooting a plurality of metallographs on the detection point, separating a white area and a green area in each metallograph according to a set gray value, determining ferrite, pearlite and a sorbing structure area in each metallograph, calculating the sorbing rate of each metallograph, and taking the average value of the sorbing rates as the sorbing rate of the cross section sample of the medium-high carbon steel wire rod.
2. The method for measuring the sorbitizing rate of the medium-high carbon steel wire rod according to claim 1, is characterized by comprising the following steps of:
step 1, cutting a sample of the cross section of a medium-high carbon steel wire rod, inlaying and polishing the sample, corroding the sample by a nitric acid alcohol solution, and drying the sample;
step 2, taking any point on the circumference of a quarter diameter position away from the center of the circle of the cross section sample of the medium-high carbon steel wire rod processed in the step 1 as a detection point, and continuously shooting a plurality of metallographic pictures on the detection point;
step 3, setting an initial gray value A, separating a white area and a green area of each metallographic picture shot in the step 2 according to the set gray value, if the initial gray value A cannot separate the white area and the green area of the metallographic picture, adjusting the gray value, stopping adjusting when the white area and the green area can be separated, and obtaining a gray value B of each metallographic picture;
step 4, manually separating the pearlite structure with larger lamellar spacing of each metallographic picture shot in the step 2 to serve as a white area, and separating according to the gray value B obtained in the step 3 and the fact that the ferrite structure is a white area and the sorbite structure is a green area, so that the ferrite, pearlite and sorbite structure areas in each metallographic picture are determined;
and 5, calculating the sorbing rate of each metallographic photograph according to the areas of the ferrite, the pearlite and the sorbing structure regions determined in the step 4 and the sorbing rate of each metallographic photograph, and calculating the average sorbing rate of the cross section sample of the medium-high carbon steel wire rod according to the sorbing rate of each metallographic photograph, namely the sorbing rate of the cross section sample of the medium-high carbon steel wire rod.
3. The method for determining the sorbite ratio of the medium-high carbon steel wire rod is characterized in that in the step 2, an optical microscope with a photographing function is adopted as equipment for photographing a metallographic picture.
4. The method for determining the sorbite ratio of the medium-high carbon steel wire rod according to claim 3, wherein the metallographic picture taken in the step 2 is the metallographic picture of the detection point obtained under a field of view with a magnification of 500 times.
5. The method for determining the sorbite ratio of the medium-high carbon steel wire rod according to claim 3, wherein in the step 4, the pearlite structure with larger lamellar spacing is a lamellar pearlite structure which can be observed under the condition of 500 times of each metallographic photograph.
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
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| CN113466230A (en) * | 2021-06-29 | 2021-10-01 | 武汉钢铁有限公司 | Quantitative measurement method for pearlite and sorbite content of high-carbon steel wire |
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| CN102901729A (en) * | 2012-09-05 | 2013-01-30 | 天津钢铁集团有限公司 | Method for quantitative analysis of wire rod sorbite content by using imager standard sample method |
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| CN102901729A (en) * | 2012-09-05 | 2013-01-30 | 天津钢铁集团有限公司 | Method for quantitative analysis of wire rod sorbite content by using imager standard sample method |
| CN103712988A (en) * | 2013-12-11 | 2014-04-09 | 攀钢集团攀枝花钢铁研究院有限公司 | Quantitative method for measuring massive martensite content in low carbon steel |
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| CN113466230A (en) * | 2021-06-29 | 2021-10-01 | 武汉钢铁有限公司 | Quantitative measurement method for pearlite and sorbite content of high-carbon steel wire |
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Application publication date: 20200221 |