CN116024417A - Manufacturing method of outer wall wear-resistant seamless steel pipe and outer wall wear-resistant seamless steel pipe - Google Patents
Manufacturing method of outer wall wear-resistant seamless steel pipe and outer wall wear-resistant seamless steel pipe Download PDFInfo
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- 238000005096 rolling process Methods 0.000 claims abstract description 13
- 238000005299 abrasion Methods 0.000 claims abstract description 7
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Abstract
The utility model relates to a manufacturing method of a seamless steel tube with an abrasion-resistant outer wall, and belongs to the field of steel manufacturing. The method comprises the steps of steelmaking, tube blank manufacturing, annular furnace heating, perforation, continuous rolling, stretch reducing or sizing and online quenching, wherein the quenching is an online quenching step and comprises the following steps: after the steel pipe is subjected to finish rolling, the water pressure and the flow of each group of water rings on the online quenching equipment are regulated to realize concentrated cooling, so that martensite structures with more than 95% are generated within 1.5mm from the outer wall of the steel pipe; the speed of a roller way for conveying the steel pipe in the online quenching cooling area is regulated so as to regulate the quenching cooling temperature gradient in the wall thickness direction of the steel pipe, indirectly control the depth of a quenching layer and regulate the proportion of martensite and non-martensite structures in the wall thickness direction of the steel pipe; and also relates to a seamless steel pipe with wear-resistant outer wall. The method can obtain the outer wall wear-resistant seamless steel pipe with the characteristics of external hardness and internal toughness.
Description
Technical Field
The utility model relates to the field of steel, in particular to a manufacturing method of an outer wall wear-resistant seamless steel pipe and the outer wall wear-resistant seamless steel pipe manufactured based on the method.
Background
The wear-resistant seamless steel pipe is widely applied to industries such as electric power, metallurgy, mine, chemical industry and the like, and is mainly used for conveying abrasive particle materials such as sand, stone, coal dust, ash slag and the like. On the one hand, the conveyed abrasive materials are required to have higher hardness and excellent wear resistance on the inner wall of the wear-resistant pipe, and on the other hand, in order to prevent low-stress brittle fracture in the service process, the wear-resistant pipe is generally required to have certain plasticity and toughness. In order to cooperatively solve the contradiction between high hardness and certain plastic toughness, the prior industry mainly adopts the ways of quenching the inner wall of a steel pipe, nesting a tough outer pipe and a wear-resistant inner pipe, and the like to produce the wear-resistant pipe.
In addition to the above-mentioned uses, when the abrasion resistant tube is used in a special scene such as a boiler water pipe, the inner wall thereof transmits water, oil or a gaseous medium, and the outer wall is in contact with hard particles or solids, requiring good abrasion resistance of the outer wall. In order to improve the wear resistance of the outer wall of the steel pipe, common methods comprise surfacing a wear-resistant layer, chromeplating and the like, and the methods have the advantages of higher cost, lower production efficiency and environmental protection.
The published patents about the outer wall wear-resistant seamless steel pipe mainly include the following items:
the utility model patent of China with publication number of CN212226263U and publication date of 2020, 12 months and 25 days, named as "high-performance compression-resistant and wear-resistant composite steel pipe" provides a high-performance compression-resistant and wear-resistant composite steel pipe. The wear-resistant inner pipe is characterized by comprising a pressure-resistant inner pipe and a wear-resistant outer pipe, an interlayer is arranged between the pressure-resistant inner pipe and the wear-resistant outer pipe, a rubber buffer layer is filled in the interlayer, a supporting structure is arranged at the end part of the interlayer, and a wear-resistant coating is coated on the outer surface of the wear-resistant outer pipe.
The utility model patent of China with publication number of CN210440696U and publication date of 2020, 5 months and 1 day, named as 'a wear-resistant seamless steel pipe', provides a wear-resistant seamless steel pipe. The novel plastic inner tube is characterized by comprising an outer base tube and an inner lining tube, wherein the inner lining tube is arranged in the outer base tube, and the novel plastic inner tube is characterized in that: the reinforced pipe comprises an outer reinforced pipe, an inner reinforced pipe and reinforced ring sheets, wherein the reinforced ring sheets are uniformly sleeved on the inner reinforced pipe, the reinforced ring sheets are connected with the inner wall of the outer reinforced pipe, the inner lining pipe is arranged in the inner reinforced pipe, and a wear-resistant layer is arranged on the outer side of the outer base pipe.
The wear-resistant seamless steel pipes disclosed by the patent are of inner and outer pipe composite structures, and are complex in structural form and high in production cost.
Disclosure of Invention
The utility model aims to overcome the defects of the prior art and provide a novel manufacturing method of an outer wall wear-resistant seamless steel pipe and the outer wall wear-resistant seamless steel pipe manufactured based on the method. The method of the utility model obtains the outer wall wear-resistant seamless steel pipe with the characteristics of external hardness and internal toughness through process adjustment.
The utility model aims to provide a manufacturing method of an outer wall wear-resistant seamless steel pipe, which realizes the control of the wall thickness direction phase transformation of the steel pipe by controlling an online quenching process, thereby ensuring that martensite with a low-temperature transformation structure is generated in a certain thickness of the outer wall of the steel pipe inwards, and the parts except a quenched martensite layer are all of a medium-temperature transformation bainite structure or even a high-temperature transformation ferrite+pearlite structure, so as to obtain the outer wall wear-resistant seamless steel pipe with the characteristics of external hardness and internal toughness.
In order to achieve the above object, the present utility model provides a method for manufacturing a seamless steel pipe with wear-resistant outer wall, comprising the steps of steelmaking, pipe blank manufacturing, annular furnace heating, perforation, continuous rolling, reducing or sizing and quenching, wherein the quenching is an on-line quenching step, and comprises the following steps:
firstly, after finishing rolling of the steel pipe, regulating the water pressure and flow of each group of water rings on the online quenching equipment to realize concentrated cooling, so that more than 95% of martensitic structure is generated within 1.5mm from the outer wall of the steel pipe;
and secondly, adjusting the speed of a roller way for conveying the steel pipe in the online quenching cooling area, adjusting the quenching cooling temperature gradient in the wall thickness direction of the steel pipe, indirectly controlling the depth of a quenching layer, and adjusting the proportion of martensite and non-martensite structures in the wall thickness direction of the steel pipe.
In the first step, the online quenching equipment is controlled so that the open cooling temperature of online quenching is more than or equal to Ar3 temperature +40 ℃ of the steel grade.
In the first step, the total opening number of the online quenching water ring is controlled to be constant, and the water ring is opened completely for different specifications/materials.
In the first step, the water pressure and the flow of each water ring of the online quenching are controlled to be constant, the water pressure in a single water ring is more than or equal to 0.45MPa, and the flow of the single water ring is more than or equal to 125m 3 /h。
In the second step, the roller way speed V (m/s) of steel pipe conveying in the online quenching cooling zone and the steel pipe wall thickness T (mm) are controlled to meet the following corresponding relation:
if T is more than or equal to 8 and less than 12 V=1.8+/-0.5;
if T is more than or equal to 12 and less than 16V=1.6+/-0.5;
if T is 16-20 V=1.4+ -0.5;
if T is more than or equal to 20 and less than 25 V=1.3+/-0.5;
if T is more than or equal to 25 and less than 30 V=1.2+/-0.5;
if T is more than or equal to 30 and less than or equal to 40 V=1.0+/-0.5.
In the second step, the temperature of the outer wall of the steel pipe out of the cooling zone is controlled to be less than or equal to Ms temperature-120 ℃.
In the manufacturing method of the seamless steel pipe with the wear-resistant outer wall, the pipe blank is manufactured by adopting a method of directly casting molten steel for smelting or adopting a method of forging or rolling after casting.
In the manufacturing method of the seamless steel pipe with the wear-resistant outer wall, when the pipe blank is heated in a ring furnace, the heating temperature is in the temperature range of 1200-1300 ℃, and the heat preservation time is 1-4 h.
Another object of the utility model is to provide an outer wall wear-resistant seamless steel pipe based on the above manufacturing method. In the outer wall wear-resistant seamless steel tube, the alloy component system is C-Si-Mn-Cr, wherein C is more than or equal to 0.5% and less than or equal to 0.7%, si is more than or equal to 0.2% and less than or equal to 0.3%, mn is more than or equal to 0.5% and less than or equal to 0.85%, and Cr is more than or equal to 0.3% and less than or equal to 0.9%. Meanwhile, in order to meet the requirement of hardenability of the steel pipe, the contents of C, mn and Cr elements in the steel meet the following requirements: cep=C+Mn/6+Cr/5 is more than or equal to 0.75%; the outer wall wear-resistant seamless steel pipe prepared by the method has the following characteristics: (1) the martensite proportion of the steel pipe within 1.5mm from the outer wall (quenching side) is more than or equal to 95%; (2) the 50% martensitic region (depth of hardening layer) of the steel pipe is between 1/2 and 2/3 of the depth of the wall thickness, namely the steel pipe is hardened from the outer wall to 1/2 to 2/3 of the depth, so that the steel pipe has better wear resistance, and the residual wall thickness is not hardened, so that certain toughness is maintained; (3) the impact absorption power Kv8 of the inner wall test sample of the steel pipe is more than or equal to 32J (test parameters are 20 ℃ C., longitudinal direction, and test sample size is 10mm x 55 mm).
Based on the technical scheme, the method and the seamless steel pipe obtained based on the method have the following technical advantages compared with the prior art:
the manufacturing method of the utility model realizes the control of the transformation of the wall thickness direction of the steel pipe by controlling the online quenching process, thereby ensuring that martensite with low-temperature transformation structure is generated in a certain thickness of the outer wall of the steel pipe inwards, and the parts except the quenched martensite layer are all of medium-temperature transformation bainite structure or even high-temperature transformation ferrite and pearlite structure, thus obtaining the outer wall wear-resistant seamless steel pipe with the characteristics of external hardness and internal toughness.
Drawings
FIG. 1 is a drawing of a typical outer wall quench-hardened layer structure of an embodiment of the present utility model, martensite+very little retained austenite.
FIG. 2 is a diagram of an exemplary inner wall unquenched ductile structure of the present utility model, which is a pearlitic+small ferrite structure.
Detailed Description
The outer wall wear-resistant seamless steel pipe and the manufacturing method thereof according to the present utility model will be further explained and illustrated with reference to specific examples, however, the explanation and illustration do not unduly limit the technical scheme of the present utility model.
The utility model relates to a manufacturing method of a seamless steel pipe with wear-resistant outer wall, which comprises the steps of manufacturing the seamless steel pipe, namely steelmaking, pipe blank manufacturing, annular furnace heating, perforation, continuous rolling, stretch reducing or sizing and quenching. As the characteristics of the utility model, the quenching is performed in an on-line quenching mode. In order to achieve the aim of the utility model, the utility model focuses on researching the online quenching process of the seamless steel tube, and the research shows that: (1) after the steel pipe is finish rolled, the water pressure and the flow of each group of water rings of the online quenching equipment are adjusted, so that the ultrahigh-speed concentrated cooling effect can be generated, and the martensitic structure of more than 95% is generated within 1.5mm from the outer wall of the steel pipe, namely 1.5mm from the outer wall, namely 1.5mm from the quenching side. (2) The quenching cooling temperature gradient in the wall thickness direction of the steel pipe can be adjusted by adjusting the speed of a roller way for conveying the steel pipe in the online quenching cooling area, so that the depth of a hardening layer is indirectly controlled, and the martensite/non-martensite structure ratio in the wall thickness direction of the steel pipe is adjusted. The research results show that the structure proportion and the final performance of the outer wall wear-resistant seamless steel pipe can be effectively adjusted through the adjustment of the online quenching process.
The method of the present utility model has been completed based on the above knowledge. In order to achieve the above object, the present utility model provides a method for manufacturing a seamless steel pipe with wear-resistant outer wall, comprising the steps of: steelmaking, tube blank manufacturing, annular furnace heating, perforation, continuous rolling, reducing or sizing and online quenching. The online quenching step comprises the following steps: (1) the on-line quenching cooling temperature is controlled to be more than or equal to Ar3 temperature +40 ℃; (2) the total opening number of the online quenching water rings is controlled to be constant, all the water rings are opened for different specifications/materials, and 42 water rings are selected in the embodiment; (3) the water pressure and the flow of each water ring of the online quenching are controlled to be constant, the water pressure in the water ring is more than or equal to 0.45MPa, and the flow of a single water ring is more than or equal to 125m 3 /h; (4) the roller way speed V of steel pipe conveying in the online quenching cooling zone and the steel pipe wall thickness T are controlled to meet the corresponding relation listed in the following table 1.
Table 1 correspondence of roller velocity V and steel pipe wall thickness T
(5) Controlling the temperature of the cooling area outside the steel pipe to be less than or equal to Ms temperature-120 ℃; (6) and directly obtaining the finished product of the seamless steel tube with the wear-resistant outer wall after the steel tube is discharged from the cooling zone.
In the manufacturing method of the seamless steel pipe with the wear-resistant outer wall, the step of manufacturing the pipe blank can adopt a method of directly casting molten steel for smelting, and can also adopt a method of forging or rolling after casting.
In the manufacturing method of the seamless steel tube with the wear-resistant outer wall, the heating temperature of the tube blank in the annular furnace is in the temperature range of 1200-1300 ℃, and the heat preservation time is 1-4 h. The heating temperature is too high or the heat preservation time is too long, which may cause coarse grains and damage the wear resistance. If the heating time is too short or the heat-retaining time is insufficient, the deformation performance of the tube blank may be poor.
In the manufacturing method of the seamless steel pipe with the wear-resistant outer wall, the water is sprayed to the outer wall of the steel pipe by the water ring, and the inner wall of the steel pipe is cooled in a mode of no water spraying, namely a single external cooling mode. The outer wall wear-resistant seamless steel tube with the characteristics of external hardness and internal toughness can be obtained.
In the manufacturing method of the seamless steel pipe with the wear-resistant outer wall, in order to ensure the wear resistance of the outer wall of the steel pipe and prevent the outer wall of the steel pipe from generating bad structures such as proeutectoid ferrite and the like in the cooling process, the on-line quenching cooling temperature should be kept above the Ar3 temperature of steel grade +40 ℃, and the Ar3 temperature of the steel grade is a clear concept in the field and refers to the starting temperature of proeutectoid ferrite transformation during supercooled austenite cooling transformation.
In the manufacturing method of the seamless steel pipe with the wear-resistant outer wall, in order to ensure the wear resistance of the outer wall of the steel pipe, the martensitic structure of the outer wall of the steel pipe needs to be ensured to be fully and finely transformed, the ultrahigh-speed concentrated cooling is beneficial to the martensitic transformation, the proportion of residual austenite in the structure is reduced, and the martensitic structure is beneficial to refining. According to the technical scheme of the utility model, the water pressure in a single water ring is more than or equal to 0.45MPa, and the flow of the single water ring is more than or equal to 125m during on-line quenching 3 And/h, so as to ensure the effect of ultrahigh-speed concentrated cooling.
In order to ensure the effect of external hardness and internal toughness of the steel pipe, the method needs to control the steel pipe to form a certain cold speed gradient along the wall thickness direction, so that a non-martensitic structure is generated in a certain area of the steel pipe from the inner wall to the outer side, and the non-martensitic structure comprises a small amount of martensite+bainite, bainite, bainite+ferrite+pearlite, ferrite+pearlite and the like. When the roller speed V of the steel pipe conveyed in the online quenching cooling zone and the wall thickness T of the steel pipe meet the corresponding relation shown in Table 1, a 50% martensitic zone (namely the depth of a hardening layer) can be between 1/2 and 2/3 of the wall thickness of the steel pipe, namely the steel pipe is hardened from the outer wall to 1/2 to 2/3 of the depth, so that the steel pipe has good wear resistance, and the rest part is not hardened and maintains certain toughness. The hardening depth ratio fluctuates between 1/2 and 2/3 depending on the steel type.
In the manufacturing method of the seamless steel tube with the wear-resistant outer wall, in order to ensure the wear resistance of the outer wall of the steel tube and improve the quenching effect of the outer wall, the temperature of a cooling area of the outer wall of the steel tube is required to be controlled to be less than or equal to Ms temperature-120 ℃, and the low final cooling temperature is beneficial to improving the proportion of martensite structures in the quenching layer.
Another object of the present utility model is to provide an outer wall wear-resistant seamless steel pipe based on the above manufacturing method, wherein the alloy composition system of the outer wall wear-resistant seamless steel pipe is C-Si-Mn-Cr, wherein:
0.5％≤C≤0.7％，
0.2％≤Si≤0.3％，
0.5％≤Mn≤0.85％，
0.3％≤Cr≤0.9％。
meanwhile, in order to meet the requirement of hardenability of the steel pipe, the contents of C, mn and Cr elements in the steel meet the requirement: cep=C+Mn/6+Cr/5 is more than or equal to 0.75%;
the outer wall wear-resistant seamless steel pipe prepared by the manufacturing process has the following characteristics:
(1) the martensite proportion of the steel pipe within 1.5mm from the outer wall (quenching side) is more than or equal to 95%;
(2) the 50% martensitic region (depth of hardening layer) of the steel pipe is between 1/2 and 2/3 of the depth of the wall thickness, namely the steel pipe is hardened from the outer wall to 1/2 to 2/3 of the depth, so that the steel pipe has better wear resistance, and the residual wall thickness is not hardened, so that certain toughness is maintained;
(3) the impact absorption power Kv8 of the inner wall test sample of the steel pipe is more than or equal to 32J (20 ℃ C., longitudinal direction, test sample size 10mm x 55 mm).
Examples
The outer wall abrasion-resistant seamless steel pipes in the above examples and comparative examples were produced by using the following steps of:
(1) Smelting, wherein the steel grade components are controlled as shown in table 1;
(2) Manufacturing a tube blank: the method of directly casting molten steel by smelting can be adopted, and the method of forging or rolling after casting can also be adopted;
(3) Heating in a ring furnace: heating the round tube blank to 1200-1300 ℃ and preserving heat for 1-4h;
(4) Perforating;
(5) Tandem rolling;
(6) Reducing or sizing, wherein the specification of the finished steel pipe is 244.8 x 24mm;
(7) And (3) online quenching: specific process data of the on-line quenching cooling temperature, the water pressure/flow rate of each water ring, the roller speed and the like of each example and comparative example are shown in Table 2;
TABLE 2 mass percent (wt%) of the chemical elements of examples A1-A8 and comparative examples B1-B6
As can be seen from table 2, the Cep values of comparative example B1 do not correspond to the parameter ranges defined in the present utility model.
Table 3 shows the specific parameters of the manufacturing processes of examples A1-A8 and comparative examples B1-B6, including heating temperature, holding time, cooling mode, ar3, chilling temperature, water pressure, water amount, roller speed, ms temperature and outer wall cooling zone temperature.
Table 3 specific parameters of examples and comparative examples
As can be further seen from table 3, the immersion cooling method adopted in comparative example B2 does not conform to the limitation of the present utility model on the cooling method of the steel pipe, the cooling temperature of comparative example B3 is lower than the limitation of the present utility model, the water pressure and water amount of comparative example B4 are lower than the limitation of the present utility model, the roller table moving speed of comparative example B5 is higher than the limitation of the present utility model, and the temperature of the cooling zone outside the steel pipe of comparative example B6 is higher than the limitation of the present utility model.
Table 4 shows the structural and mechanical properties of the seamless steel pipes of examples A1 to A8 and comparative examples B1 to B6, which were measured by air-cooling them on a cooling bed to room temperature.
TABLE 4 Table 4
In table 4 above, the metallographic structure test results were tested using the following method: after sawing and segmenting seamless steel pipes manufactured by different processes, a metallographic sample is cut at the middle part of the steel pipe, and metallographic structure analysis and test are carried out after sample preparation, as shown in fig. 1, wherein the structure of a typical outer wall hardening layer in fig. 1 is martensite+a very small amount of residual austenite. Wherein: the martensite ratio within 1.5mm from the outer wall (quenched end) was quantitatively characterized by back scattering electron diffraction (EBSD), and the depth of the 50% martensitic region (depth of quenched layer) was approximately replaced by the position of abrupt change in the hardness value of the continuous point in the diameter direction, as compared with fig. 2, which is a typical inner wall non-quenched ductile structure, which is pearlite+a small amount of ferrite structure.
As is clear from Table 4, the seamless steel pipes of examples A1 to A8 have a martensite ratio of more than 95% at a position 1.5mm from the outer wall (quenching end), and a 50% martensite region depth to wall thickness ratio of 1/2 to 2/3, which is superior to the steel pipe cross-sectional structure distribution of comparative examples B1 to B6, and not only has excellent wear resistance on the surface of the steel pipe, but also has a certain toughness on the inner wall of the steel pipe. The method can be used in the field with the requirement of wear resistance on the outer wall of the steel pipe, fully utilizes the waste heat generated in the process of manufacturing the seamless steel pipe, has convenient production process and has lower cost compared with the composite outer wall wear-resistant seamless steel pipe.
As is also apparent from table 4, the alloy element Cep value of comparative example B1 was less than 0.75%, so that the hardenability of the material was insufficient, and the depth of the 50% martensitic region of the produced steel pipe was insufficient; the cooling mode of the comparative example B2 adopts immersion quenching, the outer, middle and inner walls of the steel pipe are all quenched into a martensitic structure, the toughness of the inner wall is insufficient, and the requirements of the utility model are not met; the cooling temperature of the comparative example B3 is lower than the range defined by the utility model, so that a great proportion of proeutectoid ferrite and other bad structures are precipitated on the outer wall of the steel pipe, and the proportion of martensite structures on the outer wall of the steel pipe is lower than 95%; the quenching water pressure and flow rate of the comparative example B4 are insufficient, so that the cooling speed of the outer wall of the steel pipe is insufficient, the quenching is poor, and the martensite proportion of the steel pipe within 1.5mm from the outer wall (quenching end) and the depth of a 50% martensite region accounting for the wall thickness do not meet the requirements of the utility model; the roller way of the comparative example B5 has too high speed, so that the cooling speed of the outer wall of the steel pipe is insufficient, and the proportion of the depth of a 50% martensitic region to the wall thickness does not meet the requirement of the utility model; the steel pipe outer wall of comparative example B6 was cooled too high in final cooling temperature, resulting in insufficient cooling of the steel pipe outer wall, and the martensite ratio at a distance of 1.5mm from the outer wall (quenched end) did not meet the requirements of the present utility model.
It should be noted that the above-mentioned embodiments are merely examples of the present utility model, and it is obvious that the present utility model is not limited to the above-mentioned embodiments, and many similar variations are possible. All modifications attainable or obvious from the present disclosure set forth herein should be deemed to be within the scope of the present disclosure.
Claims (9)
1. The manufacturing approach of a wear-resisting seamless steel pipe of outer wall, this method includes steelmaking, tube blank manufacture, annular furnace heating, perforation, tandem rolling, stretch reducing or sizing, characterized by, also there is online quenching step, it includes:
firstly, after finishing rolling of the steel pipe, regulating the water pressure and flow of each group of water rings on the online quenching equipment to realize concentrated cooling, so that more than 95% of martensitic structure is generated within 1.5mm from the outer wall of the steel pipe;
and secondly, regulating the speed of a roller way for conveying the steel pipe in the online quenching cooling zone so as to regulate and control the quenching cooling temperature gradient in the wall thickness direction of the steel pipe, indirectly controlling the depth of the quenching layer, and regulating and controlling the ratio of martensite to non-martensite structures in the wall thickness direction of the steel pipe, so that the 50% martensite zone of the steel pipe is between 1/2 and 2/3 of the depth of the wall thickness.
2. The method for producing an outer wall wear-resistant seamless steel pipe according to claim 1, wherein in the first step, the on-line quenching equipment is controlled so that the cooling temperature of on-line quenching is not less than the Ar3 temperature +40 ℃ of the steel grade.
3. A method of manufacturing an outer wall abrasion resistant seamless steel pipe according to claim 1 or 2, wherein in the first step, the total number of open water rings for on-line quenching is controlled to be constant, and the water rings are all open.
4. The method for manufacturing seamless steel pipes with wear-resistant outer walls according to claim 3, wherein in the first step, the water pressure and the flow rate of each water ring of the online quenching are controlled to be constant, the water pressure in a single water ring is more than or equal to 0.45MPa, and the flow rate of a single water ring is more than or equal to 125m 3 /h。
5. A method of producing an outer wall wear-resistant seamless steel pipe according to claim 1, wherein in the second step, the roller speed V (m/s) of steel pipe transport in the on-line quenching cooling zone is controlled to satisfy the following correspondence with the steel pipe wall thickness T (mm):
if T is more than or equal to 8 and less than 12V =1.8+/-0.5;
if 12 is less than or equal to T and less than 16V =1.6+/-0.5;
if T is 16-20V =1.4+ -0.5;
if T is more than or equal to 20 and less than 25V =1.3+/-0.5;
if T is more than or equal to 25 and less than 30V =1.2+/-0.5;
if 30.ltoreq.T.ltoreq.40 40V =1.0.+ -. 0.5.
6. The method for producing an outer wall wear-resistant seamless steel pipe according to claim 1, wherein in the second step, the temperature of the outer wall of the steel pipe at the cooling zone is controlled to be equal to or lower than-120 ℃.
7. The method for manufacturing the seamless steel pipe with the abrasion-resistant outer wall according to claim 1, wherein the pipe blank is manufactured by adopting a method of directly casting molten steel for smelting or adopting a method of forging or rolling after casting.
8. The method for manufacturing the seamless steel tube with the abrasion-resistant outer wall according to claim 1, wherein the heating temperature of the tube blank is in a temperature range of 1200-1300 ℃ and the heat preservation time is 1-4h when the tube blank is heated in a ring furnace.
9. An outer wall wear-resistant seamless steel pipe produced by the manufacturing method according to any one of claims 1 to 8, wherein an alloy component system in the outer wall wear-resistant seamless steel pipe is C-Si-Mn-Cr, wherein C is more than or equal to 0.5% and less than or equal to 0.7%, si is more than or equal to 0.2% and less than or equal to 0.3%, mn is more than or equal to 0.5% and less than or equal to 0.85%, cr is more than or equal to 0.3% and less than or equal to 0.9%, and meanwhile, the contents of C, mn and Cr elements meet the requirements: cep=C+Mn/6+Cr/5 is more than or equal to 0.75%;
the martensite proportion of the steel pipe within 1.5mm from the outer wall is more than or equal to 95%;
the 50% martensitic region of the steel pipe is between 1/2 and 2/3 of the depth of the wall thickness, namely the steel pipe is hardened from the inner 1/2 to 2/3 of the depth of the outer wall;
the impact absorption power Kv8 of the inner wall test sample of the steel pipe is more than or equal to 32J, the test sample size is 10mm multiplied by 55mm when in test, the test temperature is 20 ℃, and the impact test sample is processed along the longitudinal direction.
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| JP2017206720A (en) * | 2016-05-16 | 2017-11-24 | 新日鐵住金株式会社 | Method of manufacturing seamless steel pipe |
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| CN105154765A (en) * | 2015-09-24 | 2015-12-16 | 宝山钢铁股份有限公司 | Seamless steel tube with high strength and toughness and manufacturing method thereof |
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