CN113029718A - Preparation method of bearing steel sample rod for water immersion flaw detection - Google Patents
Preparation method of bearing steel sample rod for water immersion flaw detection Download PDFInfo
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- 238000001514 detection method Methods 0.000 title claims abstract description 82
- 229910000831 Steel Inorganic materials 0.000 title claims abstract description 71
- 239000010959 steel Substances 0.000 title claims abstract description 71
- 238000007654 immersion Methods 0.000 title claims abstract description 65
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 title claims abstract description 65
- 238000002360 preparation method Methods 0.000 title claims abstract description 17
- 238000005070 sampling Methods 0.000 claims abstract description 42
- 238000000034 method Methods 0.000 claims abstract description 41
- 238000000227 grinding Methods 0.000 claims abstract description 25
- 238000000137 annealing Methods 0.000 claims abstract description 24
- 238000001816 cooling Methods 0.000 claims description 44
- 239000000463 material Substances 0.000 claims description 15
- 238000010438 heat treatment Methods 0.000 claims description 13
- 238000007599 discharging Methods 0.000 claims description 6
- 238000012360 testing method Methods 0.000 claims description 6
- 229910052804 chromium Inorganic materials 0.000 claims description 5
- 229910052802 copper Inorganic materials 0.000 claims description 5
- 239000012535 impurity Substances 0.000 claims description 5
- 229910052748 manganese Inorganic materials 0.000 claims description 5
- 229910052750 molybdenum Inorganic materials 0.000 claims description 5
- 229910052759 nickel Inorganic materials 0.000 claims description 5
- 239000000126 substance Substances 0.000 claims description 5
- 238000005096 rolling process Methods 0.000 claims description 2
- 239000013078 crystal Substances 0.000 abstract description 8
- 239000002245 particle Substances 0.000 abstract description 5
- 238000007689 inspection Methods 0.000 abstract description 4
- 238000004519 manufacturing process Methods 0.000 abstract description 4
- 238000004321 preservation Methods 0.000 abstract description 4
- 238000005265 energy consumption Methods 0.000 abstract description 2
- 238000009659 non-destructive testing Methods 0.000 abstract description 2
- 239000000523 sample Substances 0.000 description 68
- 230000000052 comparative effect Effects 0.000 description 7
- 229910001562 pearlite Inorganic materials 0.000 description 3
- 239000013072 incoming material Substances 0.000 description 2
- 238000011081 inoculation Methods 0.000 description 2
- 230000009286 beneficial effect Effects 0.000 description 1
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N1/00—Sampling; Preparing specimens for investigation
- G01N1/28—Preparing specimens for investigation including physical details of (bio-)chemical methods covered elsewhere, e.g. G01N33/50, C12Q
- G01N1/286—Preparing specimens for investigation including physical details of (bio-)chemical methods covered elsewhere, e.g. G01N33/50, C12Q involving mechanical work, e.g. chopping, disintegrating, compacting, homogenising
-
- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- C21D1/00—General methods or devices for heat treatment, e.g. annealing, hardening, quenching or tempering
- C21D1/26—Methods of annealing
- C21D1/32—Soft annealing, e.g. spheroidising
-
- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/02—Ferrous alloys, e.g. steel alloys containing silicon
-
- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/04—Ferrous alloys, e.g. steel alloys containing manganese
-
- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
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- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
- C22C38/20—Ferrous alloys, e.g. steel alloys containing chromium with copper
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- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
- C22C38/22—Ferrous alloys, e.g. steel alloys containing chromium with molybdenum or tungsten
-
- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
- C22C38/40—Ferrous alloys, e.g. steel alloys containing chromium with nickel
-
- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
- C22C38/40—Ferrous alloys, e.g. steel alloys containing chromium with nickel
- C22C38/42—Ferrous alloys, e.g. steel alloys containing chromium with nickel with copper
-
- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
- C22C38/40—Ferrous alloys, e.g. steel alloys containing chromium with nickel
- C22C38/44—Ferrous alloys, e.g. steel alloys containing chromium with nickel with molybdenum or tungsten
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N1/00—Sampling; Preparing specimens for investigation
- G01N1/28—Preparing specimens for investigation including physical details of (bio-)chemical methods covered elsewhere, e.g. G01N33/50, C12Q
- G01N1/42—Low-temperature sample treatment, e.g. cryofixation
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N1/00—Sampling; Preparing specimens for investigation
- G01N1/28—Preparing specimens for investigation including physical details of (bio-)chemical methods covered elsewhere, e.g. G01N33/50, C12Q
- G01N1/44—Sample treatment involving radiation, e.g. heat
Abstract
The invention relates to a preparation method of a bearing steel sample rod for water immersion flaw detection, and belongs to the technical field of nondestructive testing. In order to solve the problem that the conventional bearing steel sample rod cannot meet the requirement of water immersion flaw detection, the invention provides a preparation method of the bearing steel sample rod for water immersion flaw detection, which comprises the steps of sampling, isothermal spheroidizing annealing process, sample rod turning and fine grinding. The isothermal spheroidizing annealing process of the invention sets 4 different temperature heat preservation, can prevent the temperature from being reduced too fast, increases the spheroidization rate and dissolves the net-shaped carbide to lead the crystal grains of the water immersion flaw detection sample rod to be refined enough, the spheroidized structure reaches the GB/T18254-2016 standard 2-3 grade, the crystal grain size reaches the level above 7 grade, the requirement of the inspection precision of 100 mu m of the water immersion ultrasonic large-particle inclusion is met, the energy consumption is reduced by 30 percent, the production efficiency is high, the operation of personnel and the metallographic grade are facilitated, and the invention has important guiding and practical production significance for the water immersion high-frequency ultrasonic inspection of the large-particle inclusion of.
Description
Technical Field
The invention belongs to the technical field of nondestructive testing, and particularly relates to a preparation method of a bearing steel sample rod for water immersion flaw detection.
Background
The water immersion flaw detection belongs to ultrasonic detection of a high-frequency probe, and aims to detect large-particle inclusions in high-grade bearing steel, the frequency of the probe is 10-30MHZ, the minimum detection precision can reach 100 mu m, and the detection precision can be smaller if the surface smoothness of a product is good. Therefore, the water immersion flaw detection has extremely high requirement on the state of the incoming material to be detected, the grain size of the incoming material is required to reach more than 7 grades, and the spheroidized structure reaches 2-3 grades (GB/T18254-2016). The existing bearing steel sample rod has large grain size, and a spheroidized structure can not meet the requirement of water immersion flaw detection, so that the quality inspection and the metallographic grade of the bearing steel are not facilitated.
Disclosure of Invention
The invention provides a preparation method of a bearing steel sample rod for water immersion flaw detection, aiming at solving the problem that the existing bearing steel sample rod cannot meet the water immersion flaw detection requirement.
The technical scheme of the invention is as follows:
a preparation method of a bearing steel sample rod for water immersion flaw detection comprises the following steps:
step one, sampling:
sampling according to the specified length and number, wherein the material section is not bent, and the end surface is vertical to the axis;
step two, isothermal spheroidizing annealing process:
heating the sample obtained in the step one to 800 ℃, preserving heat for 2 hours, then cooling to 760-765 ℃, preserving heat for 1 hour, then cooling to 745-750 ℃, preserving heat for 1 hour, then cooling to 730-735 ℃, preserving heat for 1 hour, then cooling to 720 ℃, preserving heat for 2 hours, then cooling to below 600 ℃, and discharging;
step three, turning and finely grinding a sample rod:
turning the sample subjected to the isothermal spheroidizing annealing process in the second step to a required size, and then finely grinding the sample by using a surface grinding machine to obtain the bearing steel sample rod for water immersion flaw detection, wherein the surface grinding amount is less than or equal to 5 percent d.
Further, in the step one, the sampling is performed after the rolling material corresponding to the head billet or the tail billet of the furnace to be tested is slowly cooled and taken out of the pit.
Further, the bearing steel with the specified length of 40mm in the step one has the sampling length of 550mm, the detection length of 500mm and the sampling number of 8; the sampling length of the bearing steel with the diameter of 45mm is 550mm, the detection length is 500mm, and the number of samples is 7; the sampling length of the bearing steel with the diameter of 50mm is 550mm, the detection length is 500mm, and the number of samples is 6; the sampling length of the bearing steel with the diameter of 55mm is 550mm, the detection length is 500mm, and the number of samples is 5; the sampling length of the bearing steel with the diameter of 60mm is 550mm, the detection length is 500mm, and the number of samples is 4; the sampling length of the bearing steel with the diameter of 65mm is 550mm, the detection length is 500mm, and the number of samples is 4; the sampling length of the bearing steel with the diameter of 70mm is 550mm, the detection length is 500mm, and the number of samples is 3; the sampling length of the bearing steel with the diameter of 75mm is 350mm, the detection length is 300mm, and the number of samples is 4.
Further, the isothermal spheroidizing annealing process in the second step is to heat the sample obtained in the first step to 800 ℃, preserve heat for 2 hours, cool the furnace to 760 ℃, preserve heat for 1 hour, cool the furnace to 745 ℃, preserve heat for 1 hour, cool the furnace to 730 ℃, preserve heat for 1 hour, cool the furnace to 720 ℃, preserve heat for 2 hours, cool the furnace to below 600 ℃ and discharge the sample.
Further, the isothermal spheroidizing annealing process in the second step is to heat the sample obtained in the first step to 800 ℃, preserve heat for 2 hours, cool the furnace to 765 ℃, preserve heat for 1 hour, cool the furnace to 750 ℃, preserve heat for 1 hour, cool the furnace to 735 ℃, preserve heat for 1 hour, cool the furnace to 720 ℃, preserve heat for 2 hours, cool the furnace to below 600 ℃ and discharge the furnace.
Further, the heating rate of the heating in the second step is 3.8 ℃/min.
Further, the cooling rate of the furnace cooling in the second step is 0.5 ℃/min.
Further, the bearing steel sample rod is GCr15, and the specific chemical components comprise the following components in percentage by weight: c: 0.93-1.03%, Si: 0.15 to 0.35%, Mn: 0.25-0.45%, P is less than or equal to 0.025%, S: 0.005-0.015%, Cr: 1.3-1.60%, Mo is less than or equal to 0.10%, Ni is less than or equal to 0.30%, Cu is less than or equal to 0.25%, and the balance is Fe and inevitable impurities.
The invention has the beneficial effects that:
according to the preparation method of the bearing steel sample rod for water immersion flaw detection, provided by the invention, the isothermal spheroidizing annealing process of the bearing steel is formulated, so that the crystal grains of the water immersion flaw detection sample rod are sufficiently refined, the spheroidized structure reaches the level of GB/T18254-2016 standard 2-3, the crystal grain size reaches the level of more than 7, and the requirement of the detection precision of water immersion ultrasonic large-particle inclusions of 100 microns is met.
Compared with the traditional sample rod processing method, the method can prevent the temperature from being reduced too fast, increase the spheroidization rate and dissolve the net-shaped carbide, so that the standard precision requirement of the water immersion flaw detection sample can be met; and the energy consumption is reduced by 30 percent, the production efficiency is high, and the operation by personnel and the metallographic grade are convenient.
The invention combines the isothermal spheroidizing annealing process with better surface finish (less than 0.5 mu m), and has important guiding and practical production significance for water immersion high-frequency ultrasonic inspection (more than 100 mu m) of large-particle inclusions in high-grade bearing steel.
Drawings
FIG. 1 is a photograph of the metallographic structure of a bearing steel test bar for water immersion flaw detection prepared in example 3;
FIG. 2 is a water immersion ultrasonic flaw detection view of a bearing steel test bar for water immersion flaw detection prepared in example 3;
FIG. 3 is a photograph of the metallographic structure of a bearing steel test bar for water immersion flaw detection prepared in example 4;
FIG. 4 is a water immersion ultrasonic flaw detection view of a bearing steel test bar for water immersion flaw detection prepared in example 4;
FIG. 5 is a metallographic structure photograph of a bearing steel sample bar for water immersion flaw detection prepared in comparative example 1;
FIG. 6 is a view showing a water immersion ultrasonic flaw detection of a bearing steel test bar for water immersion flaw detection prepared in comparative example 1.
Detailed Description
The technical solutions of the present invention are further described below with reference to the following examples, but the present invention is not limited thereto, and any modifications or equivalent substitutions may be made to the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention. The process equipment or apparatus not specifically mentioned in the following examples are conventional in the art, and if not specifically mentioned, the raw materials and the like used in the examples of the present invention are commercially available; unless otherwise specified, the technical means used in the examples of the present invention are conventional means well known to those skilled in the art.
Example 1
The embodiment provides a preparation method of a bearing steel sample rod for water immersion flaw detection, which comprises the following steps:
step one, sampling:
sampling according to the specified length and number, wherein the material section is not bent, and the end surface is vertical to the axis;
step two, isothermal spheroidizing annealing process:
heating the sample obtained in the step one to 800 ℃, preserving heat for 2 hours, then cooling to 760-765 ℃, preserving heat for 1 hour, then cooling to 745-750 ℃, preserving heat for 1 hour, then cooling to 730-735 ℃, preserving heat for 1 hour, then cooling to 720 ℃, preserving heat for 2 hours, then cooling to below 600 ℃, and discharging;
step three, turning and finely grinding a sample rod:
turning the sample subjected to the isothermal spheroidizing annealing process in the second step to a required size, and then finely grinding the sample by using a surface grinding machine to obtain the bearing steel sample rod for water immersion flaw detection, wherein the surface grinding amount is less than or equal to 5 percent d.
Example 2
The embodiment provides a preparation method of a bearing steel sample rod for water immersion flaw detection.
In the embodiment, the bearing steel sample rod is GCr15, and the specific chemical components comprise the following components in percentage by weight: c: 0.93-1.03%, Si: 0.15 to 0.35%, Mn: 0.25-0.45%, P is less than or equal to 0.025%, S: 0.005-0.015%, Cr: 1.3-1.60%, Mo is less than or equal to 0.10%, Ni is less than or equal to 0.30%, Cu is less than or equal to 0.25%, and the balance is Fe and inevitable impurities.
The preparation method of the bearing steel sample rod for water immersion flaw detection comprises the following steps:
step one, sampling:
the method comprises the following steps of sampling rolled materials corresponding to a first billet or a tail billet of a furnace to be measured after slowly cooling and pit tapping, sampling according to the specified length and number, wherein the material section is not bent, the end surface is vertical to an axis, no flash or burr exists, and the mark is clear so as to avoid re-taking materials;
the sampling requirements for different specifications of product are shown in table 1.
TABLE 1
Step two, isothermal spheroidizing annealing process:
heating the sample obtained in the first step to 800 ℃ at a heating rate of 3.8 ℃/min, preserving heat for 2h, then cooling the furnace to 760-765 ℃, preserving heat for 1h, then cooling the furnace to 745-750 ℃, preserving heat for 1h, then cooling the furnace to 730-735 ℃, preserving heat for 1h, then cooling the furnace to 720 ℃, preserving heat for 2h, then cooling the furnace to below 600 ℃, discharging the sample from the furnace, wherein the cooling rate of the furnace cooling is 0.5 ℃/min;
step three, turning and finely grinding a sample rod:
turning the sample subjected to the isothermal spheroidizing annealing process in the step two to a required size according to a conventional turning method in the field, and then finely grinding the sample by using a conventional surface grinding machine in the field to obtain the bearing steel sample rod for water immersion flaw detection, wherein the surface grinding amount of the bearing steel sample rod is less than or equal to 5 percent d.
In the embodiment, an isothermal spheroidizing annealing process of isothermal spheroidizing and graded heat preservation is adopted, so that sufficient spheroidizing incubation time is ensured, crystal grains are refined, the spheroidized structure of the water immersion flaw detection sample reaches the GB/T18254-2016 standard grade 2-3, the crystal grain size reaches above grade 7, and as can be seen from a water immersion flaw detection view in FIG. 2, the sample rod prepared in the embodiment meets the water immersion flaw detection requirement.
Example 3
The embodiment provides a preparation method of a bearing steel sample rod for water immersion flaw detection.
In the embodiment, the bearing steel sample rod is GCr15, and the specific chemical components comprise the following components in percentage by weight: c: 0.93-1.03%, Si: 0.15 to 0.35%, Mn: 0.25-0.45%, P is less than or equal to 0.025%, S: 0.005-0.015%, Cr: 1.3-1.60%, Mo is less than or equal to 0.10%, Ni is less than or equal to 0.30%, Cu is less than or equal to 0.25%, and the balance is Fe and inevitable impurities.
The preparation method of the bearing steel sample rod for water immersion flaw detection comprises the following steps:
step one, sampling:
the method comprises the following steps of sampling after a rolled material corresponding to a primary billet of a furnace to be detected is slowly cooled and taken out of a pit, sampling according to the specified length and number, wherein a material section is not bent, the end surface is vertical to an axis, no flash or burr exists, and an identifier is clear so as to avoid re-taking the material;
the specification of the bearing steel of the embodiment is 40mm in diameter, 550mm in sampling length, 500mm in detection length and 8 in sampling number.
Step two, isothermal spheroidizing annealing process:
heating the sample obtained in the step one to 800 ℃ at a heating rate of 3.8 ℃/min, preserving heat for 2h, then cooling the furnace to 765 ℃, preserving heat for 1h, then cooling the furnace to 750 ℃, preserving heat for 1h, then cooling the furnace to 735 ℃, preserving heat for 1h, then cooling the furnace to 720 ℃, preserving heat for 2h, then cooling the furnace to below 600 ℃, and discharging the sample from the furnace, wherein the cooling rate of the furnace cooling is 0.5 ℃/min;
step three, turning and finely grinding a sample rod:
turning the sample subjected to the isothermal spheroidizing annealing process in the step two to a required size according to a conventional turning method in the field, and then finely grinding the sample by using a conventional surface grinding machine in the field to obtain the bearing steel sample rod for water immersion flaw detection, wherein the surface grinding amount of the bearing steel sample rod is less than or equal to 5 percent d.
In the embodiment, an isothermal spheroidizing annealing process of isothermal spheroidizing and graded heat preservation is adopted, so that sufficient spheroidizing inoculation time is ensured, and crystal grains are refined. As can be seen from fig. 1, the flaky pearlite was completely spheroidized with a spheroidization rate of 100%. The metallographic structure of the bearing steel sample rod for water immersion flaw detection is rated as 2 according to GB/T18254-2016, the grain size is rated as 8 according to GB/T6394-2017 intercept point method, the water immersion flaw detection is 8.5dB according to SEP1927-2010 standard 100um signal-to-noise ratio, and as can be seen from a water immersion flaw detection view in FIG. 2, the sample rod prepared in the embodiment meets the requirements of the water immersion flaw detection.
Example 4
The embodiment provides a preparation method of a bearing steel sample rod for water immersion flaw detection.
In the embodiment, the bearing steel sample rod is GCr15, and the specific chemical components comprise the following components in percentage by weight: c: 0.93-1.03%, Si: 0.15 to 0.35%, Mn: 0.25-0.45%, P is less than or equal to 0.025%, S: 0.005-0.015%, Cr: 1.3-1.60%, Mo is less than or equal to 0.10%, Ni is less than or equal to 0.30%, Cu is less than or equal to 0.25%, and the balance is Fe and inevitable impurities.
The preparation method of the bearing steel sample rod for water immersion flaw detection comprises the following steps:
step one, sampling:
the method comprises the following steps of sampling rolled materials corresponding to a to-be-measured furnace tail blank after slowly cooling the rolled materials out of a pit, sampling according to a specified length and number, wherein the material section is not bent, the end surface is vertical to an axis, no flash or burr exists, and the mark is clear so as to avoid re-taking the materials;
the specification of the bearing steel of the embodiment is 75mm in diameter, 350mm in sampling length, 300mm in detection length and 4 in sampling number.
Step two, isothermal spheroidizing annealing process:
heating the sample obtained in the step one to 800 ℃ at a heating rate of 3.8 ℃/min, preserving heat for 2h, then cooling the furnace to 760 ℃, preserving heat for 1h, then cooling the furnace to 745 ℃, preserving heat for 1h, then cooling the furnace to 730 ℃, preserving heat for 1h, then cooling the furnace to 720 ℃, preserving heat for 2h, then cooling the furnace to below 600 ℃, discharging the sample from the furnace, wherein the cooling rate of the furnace cooling is 0.5 ℃/min;
step three, turning and finely grinding a sample rod:
turning the sample subjected to the isothermal spheroidizing annealing process in the step two to a required size according to a conventional turning method in the field, and then finely grinding the sample by using a conventional surface grinding machine in the field to obtain the bearing steel sample rod for water immersion flaw detection, wherein the surface grinding amount of the bearing steel sample rod is less than or equal to 5 percent d.
In the embodiment, an isothermal spheroidizing annealing process of isothermal spheroidizing and graded heat preservation is adopted, so that sufficient spheroidizing inoculation time is ensured, and crystal grains are refined. As can be seen from fig. 3, the flaky pearlite was completely spheroidized with a spheroidization rate of 100%. The metallographic structure of the bearing steel sample rod for water immersion flaw detection is rated as 3 grade according to GB/T18254-2016, the grain size is rated as 8 grade according to GB/T6394-2017 intercept point method, the water immersion flaw detection is 8.0dB according to SEP1927-2010 standard 100um signal-to-noise ratio, and as can be seen from a water immersion flaw detection view in FIG. 4, the sample rod prepared in the embodiment meets the requirements of the water immersion flaw detection.
Comparative example 1
The comparative example is different from the example 4 only in that the most common isothermal spheroidizing annealing process is adopted to anneal the water immersion flaw detection sample, namely the sample obtained in the step one is heated to 800 ℃ at the heating rate of 3.8 ℃/min, the temperature is kept for 2h, then the furnace is cooled to 720 ℃, the temperature is kept for 2h, then the furnace is cooled to below 600 ℃, and the furnace is taken out, wherein the cooling rate of the furnace cooling is 0.5 ℃/min.
As can be seen from fig. 5, the present comparative example has achieved the object of spheroidization transformation of lamellar pearlite, but the global spheroidization effect is not very good. The metallographic structure of the bearing steel sample rod subjected to water immersion flaw detection in the comparative example is rated as grade 1 according to GB/T18254-2002, the grain size is rated as grade 7.5 according to GB/T6394-2017 intercept point method, and as can be seen from a water immersion flaw detection view in FIG. 6, the sample rod in the comparative example cannot meet the water immersion flaw detection, and 300um defects cannot be identified.
Claims (8)
1. A preparation method of a bearing steel sample rod for water immersion flaw detection is characterized by comprising the following steps:
step one, sampling:
sampling according to the specified length and number, wherein the material section is not bent, and the end surface is vertical to the axis;
step two, isothermal spheroidizing annealing process:
heating the sample obtained in the step one to 800 ℃, preserving heat for 2 hours, then cooling to 760-765 ℃, preserving heat for 1 hour, then cooling to 745-750 ℃, preserving heat for 1 hour, then cooling to 730-735 ℃, preserving heat for 1 hour, then cooling to 720 ℃, preserving heat for 2 hours, then cooling to below 600 ℃, and discharging;
step three, turning and finely grinding a sample rod:
turning the sample subjected to the isothermal spheroidizing annealing process in the second step to a required size, and then finely grinding the sample by using a surface grinding machine to obtain the bearing steel sample rod for water immersion flaw detection, wherein the surface grinding amount is less than or equal to 5 percent d.
2. The method for preparing the bearing steel sample rod for water immersion flaw detection according to claim 1, wherein the sampling in the first step is sampling after a rolling material corresponding to a head billet or a tail billet of the furnace to be detected is slowly cooled and taken out of a pit.
3. The method for preparing a bearing steel test bar for water immersion flaw detection according to claim 1 or 2, wherein the step one comprises the steps of sampling the bearing steel having a predetermined length of 40mm in diameter by 550mm, measuring the length by 500mm, and sampling by 8; the sampling length of the bearing steel with the diameter of 45mm is 550mm, the detection length is 500mm, and the number of samples is 7; the sampling length of the bearing steel with the diameter of 50mm is 550mm, the detection length is 500mm, and the number of samples is 6; the sampling length of the bearing steel with the diameter of 55mm is 550mm, the detection length is 500mm, and the number of samples is 5; the sampling length of the bearing steel with the diameter of 60mm is 550mm, the detection length is 500mm, and the number of samples is 4; the sampling length of the bearing steel with the diameter of 65mm is 550mm, the detection length is 500mm, and the number of samples is 4; the sampling length of the bearing steel with the diameter of 70mm is 550mm, the detection length is 500mm, and the number of samples is 3; the sampling length of the bearing steel with the diameter of 75mm is 350mm, the detection length is 300mm, and the number of samples is 4.
4. The method for preparing the bearing steel sample rod for water immersion flaw detection according to claim 3, wherein the isothermal spheroidizing annealing process in the second step is to heat the sample obtained in the first step to 800 ℃, preserve heat for 2 hours, cool the sample in a furnace to 760 ℃, preserve heat for 1 hour, cool the sample in the furnace to 745 ℃, preserve heat for 1 hour, cool the sample in the furnace to 730 ℃, preserve heat for 1 hour, cool the sample in the furnace to 720 ℃, and preserve heat for 2 hours, cool the sample in the furnace to below 600 ℃ and discharge the sample.
5. The method for preparing the bearing steel sample rod for water immersion flaw detection according to claim 4, wherein the isothermal spheroidizing annealing process in the second step is to heat the sample obtained in the first step to 800 ℃, preserve heat for 2 hours, cool the sample in a furnace to 765 ℃, preserve heat for 1 hour, cool the sample in the furnace to 750 ℃, preserve heat for 1 hour, cool the sample in the furnace to 735 ℃, preserve heat for 1 hour, cool the sample in the furnace to 720 ℃, preserve heat for 2 hours, cool the sample in the furnace to below 600 ℃ and take the sample out of the furnace.
6. The method for preparing a bearing steel sample rod for water immersion flaw detection according to claim 5, wherein the heating rate in the second step is 3.8 ℃/min.
7. The method for preparing the bearing steel sample rod for water immersion flaw detection according to claim 6, wherein the cooling rate of the furnace cooling in the second step is 0.5 ℃/min.
8. The preparation method of the bearing steel sample rod for water immersion flaw detection according to claim 7, wherein the bearing steel sample rod is GCr15, and the specific chemical components comprise, by weight: c: 0.93-1.03%, Si: 0.15 to 0.35%, Mn: 0.25-0.45%, P is less than or equal to 0.025%, S: 0.005-0.015%, Cr: 1.3-1.60%, Mo is less than or equal to 0.10%, Ni is less than or equal to 0.30%, Cu is less than or equal to 0.25%, and the balance is Fe and inevitable impurities.
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| CN114323839A (en) * | 2021-12-13 | 2022-04-12 | 青岛特殊钢铁有限公司 | Preparation method of spring steel sample suitable for water immersion ultrasonic C scanning detection |
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