CN112080618B - Control method of 82B hot-rolled wire rod core martensite and grain boundary cementite - Google Patents
Control method of 82B hot-rolled wire rod core martensite and grain boundary cementite Download PDFInfo
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- CN112080618B CN112080618B CN202011024377.2A CN202011024377A CN112080618B CN 112080618 B CN112080618 B CN 112080618B CN 202011024377 A CN202011024377 A CN 202011024377A CN 112080618 B CN112080618 B CN 112080618B
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- 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
- C21D8/00—Modifying the physical properties by deformation combined with, or followed by, heat treatment
- C21D8/06—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of rods or wires
- C21D8/065—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of rods or wires of ferrous alloys
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- 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
- C21D2211/00—Microstructure comprising significant phases
Abstract
The invention belongs to the technical field of ferrous metallurgy, and particularly relates to a control method of 82B hot-rolled wire rod core martensite and grain boundary cementite. The invention aims to solve the technical problem of providing a control method of 82B hot-rolled wire rod core martensite and grain boundary cementite. The method comprises the following steps: a. heating a casting blank or square steel with the central carbon segregation degree of 0.90-1.20, descaling by high-pressure water, rolling by a high-speed wire drawing unit, and spinning to obtain a wire rod; b. cooling the wire rod after spinning by adopting stelmor air cooling control, collecting coils and packaging to obtain the wire rod; the stelmor air cooling adopts an air cooling roller way delayed slow cooling mode, and the speed of the air cooling roller way is controlled to be 0.6-0.88 m/s. The 82B hot-rolled wire rod prepared by the method has the characteristics of moderate strength, good plasticity and the like, the sorbite rate is more than or equal to 90 percent, no core martensite exists, grain boundary cementite is less than or equal to 0.5 grade, and the drawing performance is good.
Description
Technical Field
The invention belongs to the technical field of ferrous metallurgy, and particularly relates to a control method of 82B hot-rolled wire rod core martensite and grain boundary cementite.
Background
The 82B hot-rolled wire rod is mainly used for producing prestressed steel strands, and in order to ensure the mechanical property of a finished product and improve the drawing formability, the production operation rate and the like, strict requirements are imposed on the wire breakage rate of the wire rod in the processes of drawing wire making, stranding and the like, so that the wire rod is required to have the characteristics of high strength and high plasticity, and good tissue uniformity.
The structural uniformity of the wire rod is one of the main factors causing the drawing fracture, in addition to the requirement of higher sorbite rate in the aspect of structural uniformity, the sorbite rate is required to be more than or equal to 85 percent in the standard of hot rolled wire rods for prestressed steel wires and steel strands (GBT 24238-,
the specification of the wire rod cementite and the core martensite are not more than 2.0 grade, and due to the difference of the temperature and the cooling speed of the surface and the core of the rolled wire rod and the influence of factors such as chemical component segregation and the like in the actual production process, serious abnormal structures such as martensite, grain boundary cementite and the like appear in the core of the wire rod, so that the wire rod is extremely large in sizeGround has influenced its performance, especially mechanical user of shelling, appears unusual fracture in drawing the in-process, and mostly be cup toper fracture.
Patent document CN105256119A discloses a method for controlling network cementite in an ultra-high carbon cord steel wire rod, which includes the steps of heating, rolling, cooling and the like, and is only applicable to a billet with a segregation degree of 0.94-1.06, and only the control of grain boundary cementite is considered.
Disclosure of Invention
The technical problem to be solved by the invention is to provide a control method of 82B hot-rolled wire rod core martensite and grain boundary cementite, so that the prepared 82B hot-rolled wire rod does not have the core martensite, the sorbite rate is more than or equal to 90 percent, and the grain boundary cementite is less than or equal to 0.5 grade.
The technical scheme adopted by the invention for solving the technical problems is to provide a control method of 82B hot-rolled wire rod core martensite and grain boundary cementite. The method comprises the following steps:
a. heating a casting blank or square steel with the central carbon segregation degree of 0.90-1.20, descaling by high-pressure water, rolling by a high-speed wire drawing unit, and spinning to obtain a wire rod;
b. cooling the wire rod after spinning by adopting stelmor air cooling control, collecting coils and packaging to obtain the wire rod;
the stelmor air cooling adopts an air cooling roller way delayed slow cooling mode, and the speed of the air cooling roller way is controlled to be 0.6-0.88 m/s.
Further, in the step a, the spinning temperature is 870-890 ℃; the spinning speed is 30-35 m/s.
In the method for controlling the 82B hot-rolled wire rod core martensite and the grain boundary cementite, in the step B, the speed of the stelmor air-cooled roller way is controlled as follows: the roller way speed of the 1 st section of roller way is 0.60m/s, and the roller way speed of the 13 th section of roller way is 0.88 m/s.
Preferably, the stelmor air-cooled roller way speed is controlled by: the roller way speed of the 1 st segment of roller way is 0.60m/s, the roller way speed of the 2 nd segment of roller way is 0.62m/s, the roller way speed of the 3 rd segment of roller way is 0.64m/s, the roller way speed of the 4 th segment of roller way is 0.66m/s, the roller way speed of the 5 th segment of roller way is 0.68m/s, the roller way speed of the 6 th segment of roller way is 0.70m/s, the roller way speed of the 7 th segment of roller way is 0.72m/s, the roller way speed of the 8 th segment of roller way is 0.76m/s, the roller way speed of the 9 th segment of roller way is 0.80m/s, the roller way speed of the 10 th segment of roller way is 0.84m/s, the roller way speed of the 11 th segment of roller way is 0.88m/s, the roller way speed of the 12 th segment of roller way is 0.88m/s, and the roller way speed of the 13 th segment of roller way is 0.88 m/s.
Further, in step b, the stelmor air cooling meets the following requirements:
opening 1#～4#Fan and 1#～4#A heat preservation cover and a Jialing device corresponding to the fan; control 1#～4#The flow of the fan is 20 ten thousand meters3/h；1#～4#The opening degree of the Jialing device corresponding to the fan is 100 percent.
5#～7#Blower and 5#～7#The heat preservation cover corresponding to the fan is in a closed state.
8#And 8#And then the fan and the heat preservation cover are opened.
Further, in the step b, in the stelmor air cooling process, the wire rod after spinning is spun from 4#And during the end period of the fan, the cooling speed of the wire rod is 9-30 ℃/s, and the wire rod is cooled to 560-600 ℃.
Further, in step b, in the stelmor air cooling process, the wire rod passes through 5#The cooling speed after the fan is less than or equal to 1.5 ℃/s and is kept for more than 30 s.
The beneficial effects of the invention are:
according to the method, through the control of the roller speed, the fan, the Jialing device and the heat-insulating cover, the prepared 82B hot-rolled wire rod has the characteristics of moderate strength, good plasticity and the like, the sorbite rate is more than or equal to 90 percent, no core martensite exists, grain boundary cementite is less than or equal to 0.5 grade, and the drawing performance is good.
Detailed Description
Specifically, the invention provides a control method of 82B hot-rolled wire rod core martensite and grain boundary cementite. The method comprises the following steps:
a. heating a casting blank or square steel with the central carbon segregation degree of 0.90-1.20, descaling by high-pressure water, rolling by a high-speed wire drawing unit, and spinning to obtain a wire rod;
b. cooling the wire rod after spinning by adopting stelmor air cooling control, collecting coils and packaging to obtain the wire rod;
the stelmor air cooling adopts an air cooling roller way delayed slow cooling mode, and the speed of the air cooling roller way is controlled to be 0.6-0.88 m/s.
In the step a of the invention, the spinning temperature is controlled to be 870-890 ℃; the spinning speed is 30-35 m/s for controlling the cooling speed in the subsequent cooling process and the temperature of each roller way section of the stelmor air cooling line. If the spinning speed is too high under the condition of the same spinning temperature and the same roller way speed, the stacking density of the wire rods on the roller way is higher, and the subsequent cooling speed cannot be achieved, and if the spinning speed is too low, the stacking density of the wire rods on the roller way is too low, and the subsequent cooling speed is too high.
In step b of the invention, the stelmor air-cooled roller way speed is controlled as follows: the roller way speed of the 1 st section of roller way is 0.60m/s and increases section by section, and the roller way speed of the 13 th section of roller way is 0.88 m/s. If the roller way speed is too low, the density of the wire rod on the roller way is too high, and the cooling speed of more than or equal to 9 ℃/s is difficult to achieve in the subsequent cooling process, so that the precipitation of grain boundary cementite is accelerated; if the roller way speed is too high, the cooling speed less than or equal to 1.5 ℃/s is difficult to achieve in the subsequent phase transformation process, so that the pearlite phase transformation is incomplete, and abnormal structures such as retained austenite or martensite are generated.
In step b of the invention, in the stelmor air cooling process, the wire rod after spinning is from spinning to 4#And during the end period of the fan, the cooling speed of the wire rod is 9-30 ℃/s, and the wire rod is cooled to 560-600 ℃. The aim is to reduce the structure transition temperature of the steel sheet through a higher cooling speed so as to obtain more sorbite, the space between layers is thinner, and simultaneously the precipitation of crystal boundary cementite is avoided. When the temperature is cooled to 600 ℃ or higher, it is difficult to avoid precipitation of a large amount of grain boundary cementite, and when the temperature is cooled to 560 ℃ or lower, an abnormal structure such as martensite is generated. At the same time, 1#～4#The opening degree of the Jialing device corresponding to the fan is 100 percent so as to control the temperature difference between a boundary point and a non-boundary point within 20 ℃ and ensure that And (4) keeping the evenness of the poker bars.
In step b of the invention, in the stelmor air cooling process, the wire rod passes through 5#The cooling speed after the fan is less than or equal to 1.5 ℃/s and is kept for more than 30 s. The method aims to ensure that the wire rod has sufficient transformation time to complete phase transformation and avoid martensite generation caused by center segregation and overlarge cooling speed.
The present invention is further illustrated in detail by the following specific examples.
Example 1
Preparation of hot-rolled wire rod 82B in gauge
Firstly, an 82B casting blank or square steel with central carbon segregation of 1.20 is heated by a walking beam furnace, descaled by high-pressure water, and rolled into the finished product by a 30-frame high-speed wire rolling mill
The outlet temperature of a finishing mill in a high-speed wire rolling unit is 921 ℃, the spinning temperature is controlled to 870-890 ℃ through cooling of a water cooling box, and then spinning is carried out through a spinning machine, the actual spinning temperature is 872 ℃, and the spinning speed is 30 m/s.
And (3) performing controlled cooling on the wire rod after spinning in a stelmor air cooling line, wherein the control parameters of the stelmor air cooling line are as follows:
(1) the roller way speed of the 1 st segment of roller way is 0.60m/s, the roller way speed of the 2 nd segment of roller way is 0.62m/s, the roller way speed of the 3 rd segment of roller way is 0.64m/s, the roller way speed of the 4 th segment of roller way is 0.66m/s, the roller way speed of the 5 th segment of roller way is 0.68m/s, the roller way speed of the 6 th segment of roller way is 0.70m/s, the roller way speed of the 7 th segment of roller way is 0.72m/s, the roller way speed of the 8 th segment of roller way is 0.76m/s, the roller way speed of the 9 th segment of roller way is 0.80m/s, the roller way speed of the 10 th segment of roller way is 0.84m/s, the roller way speed of the 11 th segment of roller way is 0.88m/s, the roller way speed of the 12 th segment of roller way is 0.88m/s, and the roller way speed of the 13 th segment of roller way is 0.88 m/s.
(2) Opening 1#～4#The starting value of the fan is 50Hz, and the air quantity is 20 ten thousand m3/h，1#～4#The heat preservation cover corresponding to the fan is opened, and simultaneously, 1#～4#The Jialing device corresponding to the fan is opened, the opening degree is 100 percent, and the wire rod after spinning is spun from 4 to 4#During the end period of the fan, the average cooling speed of the wire rod is 10.3 ℃/s, and the wire rod is discharged by 4 DEG C#The temperature of the blower port was 561 ℃.
(3)5#～7#Blower and 5#～7#The heat preservation cover corresponding to the fan is in a closed state, and the wire rod passes through 5#The cooling speed after the fan is less than or equal to 1.5 ℃/s, the actual average cooling speed is 1.2 ℃/s, the actual passing time in the heat-preserving cover is 35s, and the temperature of the heat-preserving cover is 519 ℃.
(4)8#And 8#And then the fan and the heat preservation cover are opened. Naturally cooling the wire rod, collecting coils, and packaging to obtain the 82B hot rolled wire rod.
Prepared by the above method
The 82B hot-rolled wire rod structure of the specification is pearlite, wherein the sorbite rate is 90%, grain boundary cementite is 0.5 grade, and no martensite structure exists; the tensile strength was 1170MPa and the reduction of area was 36%.
Example 2
Preparation of hot-rolled wire rod 82B in gauge
Firstly, an 82B casting blank or square steel with central carbon segregation of 0.9 is heated by a walking beam furnace, descaled by high-pressure water, and rolled into the product by a 30-frame high-speed wire rolling unit
The outlet temperature of a finishing mill in a high-speed wire rolling unit is 928 ℃, the spinning temperature is controlled to 870-890 ℃ through cooling of a water cooling box, and then spinning is carried out through a spinning machine, the actual spinning temperature is 890 ℃, and the spinning speed is 35 m/s.
And (3) performing controlled cooling on the wire rod after spinning on a stelmor air cooling line, wherein the control parameters of the stelmor air cooling line are as follows:
(1) the roller way speed of the 1 st segment of roller way is 0.60m/s, the roller way speed of the 2 nd segment of roller way is 0.62m/s, the roller way speed of the 3 rd segment of roller way is 0.64m/s, the roller way speed of the 4 th segment of roller way is 0.66m/s, the roller way speed of the 5 th segment of roller way is 0.68m/s, the roller way speed of the 6 th segment of roller way is 0.70m/s, the roller way speed of the 7 th segment of roller way is 0.72m/s, the roller way speed of the 8 th segment of roller way is 0.76m/s, the roller way speed of the 9 th segment of roller way is 0.80m/s, the roller way speed of the 10 th segment of roller way is 0.84m/s, the roller way speed of the 11 th segment of roller way is 0.88m/s, the roller way speed of the 12 th segment of roller way is 0.88m/s, and the roller way speed of the 13 th segment of roller way is 0.88 m/s.
(2) Opening 1#～4#The starting value of the fan is 50Hz, and the air quantity is 20 ten thousand m3/h，1#～4#The heat preservation cover corresponding to the fan is opened, and simultaneously, 1#～4#The Jialing device corresponding to the fan is opened, the opening degree is 100 percent, and the wire rod after spinning is spun from 4 to 4#During the end period of the fan, the average cooling speed of the wire rod is 9.6 ℃/s, and the wire rod is discharged by 4 DEG C#The temperature of the fan port was 600 ℃.
(3)5#～7#Blower and 5#～7#The heat preservation cover corresponding to the fan is in a closed state, and the wire rod passes through 5#The cooling speed after the fan is less than or equal to 1.5 ℃/s, the actual average cooling speed is 1.5 ℃/s, the actual passing time in the heat-preserving cover is 35s, and the temperature of the heat-preserving cover is 547 ℃.
(4)8#And 8#And then the fan and the heat preservation cover are opened. Naturally cooling the wire rod, collecting coils, and packaging to obtain the 82B hot rolled wire rod.
Prepared by the above method
The 82B hot-rolled wire rod structure of the specification is pearlite, wherein the sorbite rate is 95 percent, grain boundary cementite is 0 grade, and no martensite structure exists; the tensile strength is 1190MPa, and the reduction of area is 34%.
Example 3
Preparation of hot-rolled wire rod 82B in gauge
Firstly, an 82B casting blank or square steel with central carbon segregation of 1.12 is heated by a walking beam furnace, descaled by high-pressure water, and rolled into the finished product by a 30-frame high-speed wire rolling mill
The outlet temperature of a finishing mill in a high-speed wire rolling unit is 921 ℃, the spinning temperature is controlled to be 870-890 ℃ through cooling of a water cooling box, and then spinning is carried out through a spinning machine, the actual spinning temperature is 882 ℃, and the spinning speed is 35 m/s.
And (3) performing controlled cooling on the wire rod after spinning in a stelmor air cooling line, wherein the control parameters of the stelmor air cooling line are as follows:
(1) the roller way speed of the 1 st segment of roller way is 0.60m/s, the roller way speed of the 2 nd segment of roller way is 0.62m/s, the roller way speed of the 3 rd segment of roller way is 0.64m/s, the roller way speed of the 4 th segment of roller way is 0.66m/s, the roller way speed of the 5 th segment of roller way is 0.68m/s, the roller way speed of the 6 th segment of roller way is 0.70m/s, the roller way speed of the 7 th segment of roller way is 0.72m/s, the roller way speed of the 8 th segment of roller way is 0.76m/s, the roller way speed of the 9 th segment of roller way is 0.80m/s, the roller way speed of the 10 th segment of roller way is 0.84m/s, the roller way speed of the 11 th segment of roller way is 0.88m/s, the roller way speed of the 12 th segment of roller way is 0.88m/s, and the roller way speed of the 13 th segment of roller way is 0.88 m/s.
(2) Opening 1#～4#The starting value of the fan is 50Hz, and the air quantity is 20 ten thousand m3/h，1#～4#The heat preservation cover corresponding to the fan is opened, and simultaneously, 1#～4#The Jialing device corresponding to the fan is opened, the opening degree is 100 percent, and the wire rod after spinning is spun from 4 to 4#During the end period of the fan, the average cooling speed of the wire rod is 10.0 ℃/s, and the wire rod is discharged by 4 DEG C#The temperature of the blower port was 583 ℃.
(3)5#～7#Blower and 5#～7#The heat preservation cover corresponding to the fan is in a closed state, and the wire rod passes through 5#Cooling speed after the fan is less than or equal to 1.5 ℃/s, actual average cooling speed is 1.4 ℃/s, and the cooling effect is achieved in a heat-insulating coverThe actual passage time was 35s and the temperature out of the holding hood was 534 ℃.
(4)8#And 8#And then the fan and the heat preservation cover are opened. Naturally cooling the wire rod, collecting coils, and packaging to obtain the 82B hot rolled wire rod.
Prepared by the above method
The 82B hot-rolled wire rod structure of the specification is pearlite, wherein the sorbite rate is 95 percent, grain boundary cementite is 0 grade, and no martensite structure exists; the tensile strength is 1195MPa, and the reduction of area is 36%.
Comparative example 1
Preparation of hot-rolled wire rod 82B in gauge
Firstly, an 82B casting blank or square steel with central carbon segregation of 1.20 is heated by a walking beam furnace, descaled by high-pressure water, and rolled into the finished product by a 30-frame high-speed wire rolling mill
The outlet temperature of a finishing mill in a high-speed wire rolling unit is 920 ℃, the spinning temperature is controlled to be 870-890 ℃ through cooling of a water cooling box, then spinning is carried out through a spinning machine, the actual spinning temperature is 871 ℃, and the spinning speed is 30 m/s.
And (3) performing controlled cooling on the wire rod after spinning on a stelmor air cooling line, wherein the control parameters of the stelmor air cooling line are as follows:
(1) the roller way speed of the 1 st segment of roller way is 0.60m/s, the roller way speed of the 2 nd segment of roller way is 0.62m/s, the roller way speed of the 3 rd segment of roller way is 0.64m/s, the roller way speed of the 4 th segment of roller way is 0.66m/s, the roller way speed of the 5 th segment of roller way is 0.68m/s, the roller way speed of the 6 th segment of roller way is 0.70m/s, the roller way speed of the 7 th segment of roller way is 0.72m/s, the roller way speed of the 8 th segment of roller way is 0.76m/s, the roller way speed of the 9 th segment of roller way is 0.80m/s, the roller way speed of the 10 th segment of roller way is 0.84m/s, the roller way speed of the 11 th segment of roller way is 0.88m/s, the roller way speed of the 12 th segment of roller way is 0.88m/s, and the roller way speed of the 13 th segment of roller way is 0.88 m/s.
(2)1#～8#The fan is all turned on 1#～8#The heat preservation cover corresponding to the fan is opened completely, wherein 1#～4#The starting value of the fan is 45Hz, and the air quantity is 18 ten thousand m3/h，5#～8#The starting value of the fan is 40Hz, and the air quantity is 12.8 ten thousand m3/h。
(3)8#And 8#And then, closing all fans, opening all corresponding heat-insulating covers, naturally cooling, collecting and bundling to obtain the 82B hot-rolled wire rod.
Prepared by the above method
The 82B hot-rolled wire rod structure of the specification is pearlite, wherein the sorbite rate is 85 percent, the grain boundary cementite is 2.5 grade, and the martensite structure is 2.5 grade; the tensile strength is 1187MPa, and the reduction of area is 26%.
In comparison with example 1, comparative example 1 caused precipitation of proeutectoid cementite at the grain boundary due to a reduction in the early-stage cooling rate; at the same time increase by 5#～8#The cooling speed of the fan causes the residual austenite in the core of the wire rod to be transformed into a martensite structure. The increase of abnormal tissue also leads to the reduction of the area shrinkage.
Comparative example 2
Preparation of hot-rolled wire rod 82B in gauge
Firstly, an 82B casting blank or square steel with central carbon segregation of 0.90 is heated by a walking beam furnace, descaled by high-pressure water, and rolled into the product by a 30-frame high-speed wire rolling unit
The outlet temperature of a finishing mill in a high-speed wire rolling unit is 950 ℃, and then the spinning is carried out by a spinning machine, the actual spinning temperature is 913 ℃, and the spinning speed is 35 m/s.
And (3) performing controlled cooling on the wire rod after spinning in a stelmor air cooling line, wherein the control parameters of the stelmor air cooling line are as follows:
(1) the roller way speed of the 1 st section of roller way is 0.60m/s, the roller way speed of the 2 nd section of roller way is 0.62m/s, the roller way speed of the 3 rd section of roller way is 0.64m/s, the roller way speed of the 4 th section of roller way is 0.66m/s, the roller way speed of the 5 th section of roller way is 0.68m/s, the roller way speed of the 6 th section of roller way is 0.70m/s, the roller way speed of the 7 th section of roller way is 0.72m/s, the roller way speed of the 8 th section of roller way is 0.76m/s, the roller way speed of the 9 th section of roller way is 0.80m/s, the roller way speed of the 10 th section of roller way is 0.84m/s, the roller way speed of the 11 th section of roller way is 0.88m/s, the roller way speed of the 12 th section of roller way is 0.88m/s, and the roller way speed of the 13 th section of roller way is 0.88 m/s.
(2)1#～4#The fan is completely started, the starting value is 50Hz, and the air quantity is 20 ten thousand m3/h，1#～4#The heat preservation cover corresponding to the fan is completely opened, and simultaneously, 1#～4#The opening degree of the Jialing device corresponding to the fan is 100 percent, and the wire rod after spinning is from 4 to 4#During the end period of the fan, the average cooling speed of the wire rod is 8.4 ℃/s, and the wire rod is discharged by 4 DEG C#The temperature of the fan port was 680 ℃.
(3)5#～7#Fan and 5#～7#And closing the heat-preserving cover corresponding to the fan, cooling the heat-preserving cover at a cooling speed lower than 1.5 ℃/s, wherein the actual average cooling speed is 1.5 ℃/s, the actual passing time in the heat-preserving cover is 35s, and the temperature of the heat-preserving cover is 610 ℃.
(4) Opening 8#And 8#And then the fan and the corresponding heat preservation cover are cooled naturally, and then the hot-rolled wire rod 82B is collected and bundled to obtain the hot-rolled wire rod.
Prepared by the above method
The 82B hot-rolled wire rod structure of the specification is pearlite, wherein the sorbite rate is 85 percent, grain boundary cementite is 4.0 grade, and no martensite structure exists; the tensile strength is 1190MPa, and the reduction of area is 23%.
Comparative example 2 caused early cold due to the increase in laying temperature, compared to example 2Lower speed ratio example 2, out 4#The temperature of the fan is also higher, at 4#When the blower enters the heat-insulating cover, the blower is still in a high-temperature state before phase change, so that a large amount of eutectoid cementite is precipitated at a crystal boundary.
Claims (5)
1.82B hot-rolled wire rod core martensite and grain boundary cementite control method, which is characterized in that: the method comprises the following steps:
a. heating a casting blank or square steel with the central carbon segregation degree of 0.90-1.20, descaling by high-pressure water, rolling by a high-speed wire drawing unit, and spinning to obtain a wire rod;
b. cooling the wire rod after spinning by adopting stelmor air cooling control, collecting coils and packaging to obtain the wire rod; the stelmor air cooling adopts an air cooling roller way delayed slow cooling mode, the speed of the air cooling roller way is controlled to be 0.6-0.88 m/s, and the speed of the stelmor air cooling roller way is controlled as follows: the roller way speed of the 1 st segment of roller way is 0.60m/s, the roller way speed of the 2 nd segment of roller way is 0.62m/s, the roller way speed of the 3 rd segment of roller way is 0.64m/s, the roller way speed of the 4 th segment of roller way is 0.66m/s, the roller way speed of the 5 th segment of roller way is 0.68m/s, the roller way speed of the 6 th segment of roller way is 0.70m/s, the roller way speed of the 7 th segment of roller way is 0.72m/s, the roller way speed of the 8 th segment of roller way is 0.76m/s, the roller way speed of the 9 th segment of roller way is 0.80m/s, the roller way speed of the 10 th segment of roller way is 0.84m/s, the roller way speed of the 11 th segment of roller way is 0.88m/s, the roller way speed of the 12 th segment of roller way is 0.88m/s, and the roller way speed of the 13 th segment of roller way is 0.88 m/s;
in the step b, stelmor air cooling meets the following requirements:
Opening 1#～4#Fan and 1#～4#A heat preservation cover and a Jialing device corresponding to the fan; control 1#～4#The flow of the fan is 20 ten thousand meters3/h；1#～4#The opening degree of the Jialing device corresponding to the fan is 100 percent;
5#～7#blower and 5#～7#The heat preservation cover corresponding to the fan is in a closed state;
8#and 8#And then the fan and the heat preservation cover are opened.
2. The method of claim 1, wherein the method comprises the steps of: in the step a, the spinning temperature is 870-890 ℃; the spinning speed is 30-35 m/s.
3. The method of claim 1, wherein the method comprises the steps of: in the step b, in the stelmor air cooling process, the wire rod after spinning is from spinning to 4#And during the end period of the fan, the cooling speed of the wire rod is 9-30 ℃/s, and the wire rod is cooled to 560-600 ℃.
4. The method of claim 2, wherein the method comprises the steps of: in the step b, in the stelmor air cooling process, the wire rod after spinning is from spinning to 4#And during the end period of the fan, the cooling speed of the wire rod is 9-30 ℃/s, and the wire rod is cooled to 560-600 ℃.
5. The method for controlling 82B hot-rolled wire rod core martensite and grain boundary cementite according to any one of claims 1 to 4, wherein: in the step b, in the stelmor air cooling process, the wire rod passes through 5 #The cooling speed after the fan is less than or equal to 1.5 ℃/s and is kept for more than 30 s.
Priority Applications (1)
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| CN114571139A (en) * | 2022-03-04 | 2022-06-03 | 新疆八一钢铁股份有限公司 | Production process of steel for H08A welding rod for mechanical shelling |
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