CN111876571A - Production method for improving comprehensive mechanical property of T91 seamless steel tube - Google Patents
Production method for improving comprehensive mechanical property of T91 seamless steel tube Download PDFInfo
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- CN111876571A CN111876571A CN202010728170.7A CN202010728170A CN111876571A CN 111876571 A CN111876571 A CN 111876571A CN 202010728170 A CN202010728170 A CN 202010728170A CN 111876571 A CN111876571 A CN 111876571A
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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
- C21D8/10—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of tubular bodies
- C21D8/105—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of tubular bodies of ferrous alloys
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
- B21C—MANUFACTURE OF METAL SHEETS, WIRE, RODS, TUBES OR PROFILES, OTHERWISE THAN BY ROLLING; AUXILIARY OPERATIONS USED IN CONNECTION WITH METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL
- B21C37/00—Manufacture of metal sheets, bars, wire, tubes or like semi-manufactured products, not otherwise provided for; Manufacture of tubes of special shape
- B21C37/06—Manufacture of metal sheets, bars, wire, tubes or like semi-manufactured products, not otherwise provided for; Manufacture of tubes of special shape of tubes or metal hoses; Combined procedures for making tubes, e.g. for making multi-wall tubes
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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
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- C21D1/18—Hardening; Quenching with or without subsequent tempering
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- C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
- C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
- C23C22/00—Chemical surface treatment of metallic material by reaction of the surface with a reactive liquid, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals
- C23C22/73—Chemical surface treatment of metallic material by reaction of the surface with a reactive liquid, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals characterised by the process
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Abstract
The invention belongs to the technical field of metal material modification, and particularly relates to a method for improving comprehensive mechanical properties of a T91 seamless steel tube. And then quenching and tempering the rolled steel pipe in an optimized process to obtain a T91 finished pipe with excellent comprehensive mechanical properties. The method enables high-density dislocation obtained by the first pass of rolling to be reserved, and the second pass of rolling further improves the dislocation density and refines grains. Quenching further refines the microstructure, tempering forms alloy carbon/nitride in the T91 steel in a dispersed manner, further improves the strength and the hardness of the seamless steel pipe through dispersion strengthening, and simultaneously does not obviously reduce the plasticity.
Description
Technical Field
The invention belongs to the technical field of metal material modification, and particularly relates to a production method for improving comprehensive mechanical properties of a T91 seamless tube.
Background
The T91 steel has high strength, good plasticity and good oxidation resistance and corrosion resistance, and can be used for manufacturing heated surface pipes such as a reheater and a superheater of a high-pressure boiler with a metal wall temperature of less than 625 ℃ and steam guide pipes with a metal wall temperature of less than or equal to 600 ℃ and the like. At present, T91 seamless steel tubes have gradually occupied the main position of manufacturing large-capacity subcritical and supercritical power station boilers in China.
The tensile strength of a finished pipe obtained by the traditional T91 production process is 680-700 MPa, the yield strength is 520-540 MPa, the hardness is 200 HBW-220 HBW, and the service conditions of certain specific environments such as Supercritical (SC) and Ultra Supercritical (USC) unit pipes and the like are still difficult to meet, wherein the service conditions include that the steam pressure is more than or equal to 25MPa, the steam temperature is more than or equal to 580 ℃, the normal-temperature tensile strength is required to be more than or equal to 750MPa, the yield strength is more than or equal to 580MPa, and the hardness is about 250 HBW. Meanwhile, the traditional T91 production process has a long period, and cannot achieve the effects of energy conservation and high efficiency.
Disclosure of Invention
The technical problem to be solved by the invention is as follows: based on the technical problems, the invention provides a production technology and a process method for improving the comprehensive mechanical property of a T91 seamless steel tube.
The technical scheme adopted by the invention for solving the technical problems is as follows: a production technology and a process method for improving comprehensive mechanical properties of a T91 seamless tube comprise the following steps:
(1) the hot-rolled and annealed T91 seamless steel pipe is selected as a research object.
The specification of the steel tube is phi 82mm multiplied by 8.5 mm.
(2) Performing two-pass cold rolling on an LG325-H two-roll cold rolling mill, performing only phosphating treatment without annealing in the middle of the two-pass cold rolling, and performing deoiling treatment on the steel pipe after rolling;
the phosphating treatment comprises the following steps: putting the steel pipe into a phosphating solution at the temperature of 50-70 ℃ for soaking for 30-40 min, wherein the mass ratio of the phosphating solution to water is 1: 10.
the cold rolling process comprises the following steps: the total cold rolling deformation is 60-65%, and the first-pass rolling deformation is 40-50%; the rolling deformation of the second pass is 22-26%, and annealing is not carried out between the two passes.
Deoiling treatment: cleaning the surface and the inner wall of a rolled steel pipe by using an alkaline metal degreasing and degreasing powder aqueous solution, and removing grease and oil stains on the surface and the inner wall, wherein the mass ratio of degreasing powder to water is 1: 5.
(3) and quenching and tempering the rolled steel pipe to obtain a finished pipe.
Preheating twice before quenching: the primary preheating temperature is 500-600 ℃, the heat preservation time is 10min, the secondary preheating temperature is 800-850 ℃, and the heat preservation time is 10 min.
The quenching process comprises the following steps: the temperature is 1040-1060 ℃, the heat preservation time is 10min, and the cooling mode is air cooling. The tempering process comprises the following steps: the temperature is 760-780 ℃, the heat preservation time is 60min, and the cooling mode is air cooling.
(4) And sampling, detecting and analyzing the finished pipe. The test analysis specifically comprises:
1) observing the microscopic structure of the section by adopting an optical metallographic microscope;
2) performing hardness test analysis by using a Brinell hardness tester;
3) and (4) carrying out related mechanical property test analysis by adopting a multifunctional tensile testing machine.
The invention idea is as follows:
in the cold rolling process, dislocations are continuously formed along with the progress of plastic deformation, and the dislocation density is continuously increased, causing work hardening. The conventional cold rolling process needs annealing in the middle of two-pass rolling, and in the annealing process, recrystallization occurs, the dislocation density is reduced, the strength and the hardness of the steel pipe are reduced, the plasticity is improved, and the next-pass rolling is facilitated. The invention omits the intermediate annealing step, adopts proper deformation amount through the first pass rolling, and directly performs the second pass rolling after only performing phosphating treatment without annealing between the two passes of rolling under the condition that the hardness of the steel pipe meets the requirement of the second pass rolling, thereby keeping the high-density dislocation obtained by the first pass rolling, further improving the dislocation density and refining the crystal grains by performing the second pass rolling on the basis, and obviously improving the strength and the hardness of the steel pipe.
On the basis, the T91 seamless tube is subjected to quenching treatment, based on the inheritance of the structure in the heat treatment process, austenite grains which are finer than those of the traditional method can be obtained in the process of austenitizing by quenching and heating, austenite is converted into martensite with fine grains in the cooling process, and the strength of the T91 seamless tube is improved by fine grain strengthening. In the tempering process, carbon/nitride forming elements such as V, Nb and Cr in the T91 steel and C/N form alloy carbon/nitride, the alloy carbon/nitride is preferentially dispersed and precipitated at crystal defects such as dislocation, grain boundary and the like, and fine dispersed carbon/nitride can effectively prevent dislocation movement, so that the strength of the T91 steel seamless tube is greatly improved.
The invention has the beneficial effects that:
(1) the invention optimizes the cold rolling process, saves the intermediate annealing step of the traditional cold rolling process, and retains the high-density dislocation obtained by the first rolling, thereby further refining the crystal grains and improving the strength and the hardness of the T91 seamless tube. Meanwhile, the annealing process is omitted, so that the logistics process can be simplified, the production efficiency is improved, and the production cost is reduced.
(2) Compared with the conventional one-time preheating, the method provided by the invention has the advantages that the final heat treatment process is optimized, and the method is used for carrying out twice preheating before quenching, so that the deformation and cracking tendency of the T91 seamless tube in the quenching and heating process can be reduced, the heat preservation time of the T91 seamless tube in the quenching and heating process is shortened, the oxidation and decarburization of the T91 seamless tube are reduced or avoided, the burning loss is reduced, and the furnace temperature stability can be accurately controlled.
The invention is further described below with reference to the accompanying drawings.
Drawings
FIG. 1 is the structure of the finished tube obtained in example 1;
FIG. 2 is the structure of the finished tube obtained in example 2;
FIG. 3 is the structure of the finished tube obtained in example 3;
FIG. 4 is the structure of the finished tube obtained in example 4;
FIG. 5 is a structure of a finished tube obtained in comparative example 1;
FIG. 6 is a sample of the finished tube crush test obtained in example 1;
FIG. 7 is a sample of the finished tube crush test obtained in example 2;
FIG. 8 is a sample of the finished tube crush test obtained in example 3;
FIG. 9 is a sample of the finished tube crush test obtained in example 4;
FIG. 10 shows macrocracks in the crush test of the finished tube obtained in comparative example 2.
Detailed Description
The present invention is further described below with reference to examples, but is not limited thereto.
Example 1
(1) Selecting a hot-rolled and annealed T91 seamless tube as a research object, wherein the specification of the tube is phi 82mm multiplied by 8.5 mm;
(2) the steel pipe is subjected to two times of cold rolling, the phosphating treatment is carried out in the middle of the two times of cold rolling, the steel pipe is subjected to deoiling treatment after rolling, and the cold rolling process comprises the following steps: the total deformation of cold rolling is 60 percent, and the deformation of the first pass rolling is 45 percent; the rolling deformation of the second pass is 26%, and annealing is not carried out between the two passes;
(3) and quenching and tempering the rolled steel pipe to obtain a finished pipe. Preheating twice for 500 ℃ before quenching, and keeping the temperature for 10min, wherein the preheating temperature for the second time is 800 ℃, and the keeping time for the second time is 10 min. The quenching temperature is 1040 ℃, the heat preservation time is 10min, and the cooling mode is air cooling. Tempering temperature is 760 ℃, heat preservation time is 60min, and cooling mode is air cooling;
(4) cutting an annular sample from a finished tube, polishing two sections to a mirror surface, and performing hardness test analysis by using a Brinell hardness tester;
(5) cutting an arc-shaped sample with a central angle of 45-60 degrees from the annular sample, and observing a section microstructure by using an optical metallographic microscope;
(6) and (4) according to national standard GBT2975-2018, cutting out a mechanical sample from the finished product pipe, and performing related mechanical property test analysis by using a multifunctional tensile testing machine.
Example 2
(1) Selecting a hot-rolled and annealed T91 seamless tube as an experimental object, wherein the specification of the steel tube is phi 82mm multiplied by 8.5 mm;
(2) cold rolling the steel pipe, carrying out phosphating treatment in the middle of two times of rolling, and carrying out deoiling treatment on the steel pipe after rolling, wherein the cold rolling process comprises the following steps: the total deformation of cold rolling is 65 percent, and the deformation of the first pass rolling is 50 percent; the rolling deformation of the second pass is 24%, and annealing is not carried out between the two passes;
(4) and quenching and tempering the rolled steel pipe to obtain a finished pipe. Preheating twice before quenching: the primary preheating temperature is 500 ℃, the heat preservation time is 10min, the secondary preheating temperature is 800 ℃, and the heat preservation time is 10 min. The quenching temperature is 1040 ℃, the heat preservation time is 10min, and the cooling mode is air cooling. Tempering temperature is 760 ℃, heat preservation time is 60min, and cooling mode is air cooling;
(5) cutting an annular sample from a finished tube, polishing two sections to a mirror surface, and performing hardness test analysis by using a Brinell hardness tester;
(6) cutting an arc-shaped sample with a central angle of 45-60 degrees from the annular sample, and observing a section microstructure by using an optical metallographic microscope;
(7) and (4) according to national standard GBT2975-2018, cutting out a mechanical sample from the finished product pipe, and performing related mechanical property test analysis by using a multifunctional tensile testing machine.
Example 3
(1) Selecting a hot-rolled and annealed T91 seamless tube as an experimental object, wherein the specification of the steel tube is phi 82mm multiplied by 8.5 mm;
(2) cold rolling the steel pipe, carrying out phosphating treatment in the middle of two times of rolling, and carrying out deoiling treatment on the steel pipe after rolling, wherein the cold rolling process comprises the following steps: the total deformation of cold rolling is 63 percent, and the deformation of the first pass rolling is 50 percent; the rolling deformation of the second pass is 22%, and annealing is not carried out between the two passes;
(4) and quenching and tempering the rolled steel pipe to obtain a finished pipe. Preheating twice before quenching: the primary preheating temperature is 500 ℃, the heat preservation time is 10min, the secondary preheating temperature is 800 ℃, and the heat preservation time is 10 min. The quenching temperature is 1040 ℃, the heat preservation time is 10min, and the cooling mode is air cooling. Tempering temperature is 760 ℃, heat preservation time is 60min, and cooling mode is air cooling;
(5) cutting an annular sample from a finished tube, polishing two sections to a mirror surface, and performing hardness test analysis by using a Brinell hardness tester;
(6) cutting an arc-shaped sample with a central angle of 45-60 degrees from the annular sample, and observing a section microstructure by using an optical metallographic microscope;
(7) and (4) according to national standard GBT2975-2018, cutting out a mechanical sample from the finished product pipe, and performing related mechanical property test analysis by using a multifunctional tensile testing machine.
Example 4
(1) Selecting a hot-rolled and annealed T91 seamless tube as an experimental object, wherein the specification of the steel tube is phi 82mm multiplied by 8.5 mm;
(2) cold rolling the steel pipe, carrying out phosphating treatment in the middle of two times of rolling, and carrying out deoiling treatment on the steel pipe after rolling, wherein the cold rolling process comprises the following steps: the total deformation of cold rolling is 60 percent, and the deformation of the first pass rolling is 40 percent; the rolling deformation of the second pass is 26%, and annealing is not carried out between the two passes;
(4) and quenching and tempering the rolled steel pipe to obtain a finished pipe. Preheating twice before quenching: the primary preheating temperature is 500 ℃, the heat preservation time is 10min, the secondary preheating temperature is 800 ℃, and the heat preservation time is 10 min. The quenching temperature is 1040 ℃, the heat preservation time is 10min, and the cooling mode is air cooling. Tempering temperature is 760 ℃, heat preservation time is 60min, and cooling mode is air cooling;
(5) cutting an annular sample from a finished tube, polishing two sections to a mirror surface, and performing hardness test analysis by using a Brinell hardness tester;
(6) cutting an arc-shaped sample with a central angle of 45-60 degrees from the annular sample, and observing a section microstructure by using an optical metallographic microscope;
(7) and (4) according to national standard GBT2975-2018, cutting out a mechanical sample from the finished product pipe, and performing related mechanical property test analysis by using a multifunctional tensile testing machine.
Example 5
(1) Selecting a hot-rolled and annealed T91 seamless tube as a research object, wherein the specification of the tube is phi 82mm multiplied by 8.5 mm;
(2) the steel pipe is subjected to two times of cold rolling, the phosphating treatment is carried out in the middle of the two times of cold rolling, the steel pipe is subjected to deoiling treatment after rolling, and the cold rolling process comprises the following steps: the total deformation of cold rolling is 60 percent, and the deformation of the first pass rolling is 45 percent; the rolling deformation of the second pass is 26%, and annealing is not carried out between the two passes;
(3) and quenching and tempering the rolled steel pipe to obtain a finished pipe. Preheating twice for 500 ℃ before quenching, and keeping the temperature for 10min, wherein the preheating temperature for the second time is 800 ℃, and the keeping time for the second time is 10 min. The quenching temperature is 1050 ℃, the heat preservation time is 10min, and the cooling mode is air cooling. Tempering temperature is 760 ℃, heat preservation time is 60min, and cooling mode is air cooling;
(4) cutting an annular sample from a finished tube, polishing two sections to a mirror surface, and performing hardness test analysis by using a Brinell hardness tester;
(5) cutting an arc-shaped sample with a central angle of 45-60 degrees from the annular sample, and observing a section microstructure by using an optical metallographic microscope;
(6) and (4) according to national standard GBT2975-2018, cutting out a mechanical sample from the finished product pipe, and performing related mechanical property test analysis by using a multifunctional tensile testing machine.
Example 6
(1) Selecting a hot-rolled and annealed T91 seamless tube as a research object, wherein the specification of the tube is phi 82mm multiplied by 8.5 mm;
(2) the steel pipe is subjected to two times of cold rolling, the phosphating treatment is carried out in the middle of the two times of cold rolling, the steel pipe is subjected to deoiling treatment after rolling, and the cold rolling process comprises the following steps: the total deformation of cold rolling is 60 percent, and the deformation of the first pass rolling is 45 percent; the rolling deformation of the second pass is 26%, and annealing is not carried out between the two passes;
(3) and quenching and tempering the rolled steel pipe to obtain a finished pipe. Preheating twice for 500 ℃ before quenching, and keeping the temperature for 10min, wherein the preheating temperature for the second time is 800 ℃, and the keeping time for the second time is 10 min. The quenching temperature is 1060 ℃, the heat preservation time is 10min, and the cooling mode is air cooling. Tempering temperature is 760 ℃, heat preservation time is 60min, and cooling mode is air cooling;
(4) cutting an annular sample from a finished tube, polishing two sections to a mirror surface, and performing hardness test analysis by using a Brinell hardness tester;
(5) cutting an arc-shaped sample with a central angle of 45-60 degrees from the annular sample, and observing a section microstructure by using an optical metallographic microscope;
(6) and (4) according to national standard GBT2975-2018, cutting out a mechanical sample from the finished product pipe, and performing related mechanical property test analysis by using a multifunctional tensile testing machine.
Example 7
(1) Selecting a hot-rolled and annealed T91 seamless tube as a research object, wherein the specification of the tube is phi 82mm multiplied by 8.5 mm;
(2) the steel pipe is subjected to two times of cold rolling, the phosphating treatment is carried out in the middle of the two times of cold rolling, the steel pipe is subjected to deoiling treatment after rolling, and the cold rolling process comprises the following steps: the total deformation of cold rolling is 60 percent, and the deformation of the first pass rolling is 45 percent; the rolling deformation of the second pass is 26%, and annealing is not carried out between the two passes;
(3) and quenching and tempering the rolled steel pipe to obtain a finished pipe. Preheating twice for 500 ℃ before quenching, and keeping the temperature for 10min, wherein the preheating temperature for the second time is 800 ℃, and the keeping time for the second time is 10 min. The quenching temperature is 1050 ℃, the heat preservation time is 10min, and the cooling mode is air cooling. Tempering temperature is 770 ℃, heat preservation time is 60min, and cooling mode is air cooling;
(4) cutting an annular sample from a finished tube, polishing two sections to a mirror surface, and performing hardness test analysis by using a Brinell hardness tester;
(5) cutting an arc-shaped sample with a central angle of 45-60 degrees from the annular sample, and observing a section microstructure by using an optical metallographic microscope;
(6) and (4) according to national standard GBT2975-2018, cutting out a mechanical sample from the finished product pipe, and performing related mechanical property test analysis by using a multifunctional tensile testing machine.
Example 8
(1) Selecting a hot-rolled and annealed T91 seamless tube as a research object, wherein the specification of the tube is phi 82mm multiplied by 8.5 mm;
(2) the steel pipe is subjected to two times of cold rolling, the phosphating treatment is carried out in the middle of the two times of cold rolling, the steel pipe is subjected to deoiling treatment after rolling, and the cold rolling process comprises the following steps: the total deformation of cold rolling is 60 percent, and the deformation of the first pass rolling is 45 percent; the rolling deformation of the second pass is 26%, and annealing is not carried out between the two passes;
(3) and quenching and tempering the rolled steel pipe to obtain a finished pipe. Preheating twice for 500 ℃ before quenching, and keeping the temperature for 10min, wherein the preheating temperature for the second time is 800 ℃, and the keeping time for the second time is 10 min. The quenching temperature is 1050 ℃, the heat preservation time is 10min, and the cooling mode is air cooling. Tempering temperature is 780 ℃, heat preservation time is 60min, and cooling mode is air cooling;
(4) cutting an annular sample from a finished tube, polishing two sections to a mirror surface, and performing hardness test analysis by using a Brinell hardness tester;
(5) cutting an arc-shaped sample with a central angle of 45-60 degrees from the annular sample, and observing a section microstructure by using an optical metallographic microscope;
(6) and (4) according to national standard GBT2975-2018, cutting out a mechanical sample from the finished product pipe, and performing related mechanical property test analysis by using a multifunctional tensile testing machine.
Comparative example 1
(1) Selecting a hot-rolled and annealed T91 seamless tube as an experimental object, wherein the specification of the steel tube is phi 82mm multiplied by 8.5 mm;
(2) cold rolling the steel pipe, and deoiling the steel pipe after rolling, wherein the cold rolling process comprises the following steps: the total deformation of cold rolling is 60 percent, and the deformation of the first pass rolling is 45 percent; the rolling deformation of the second pass is 26%, the stress relief annealing is carried out between the two passes, the annealing temperature is 850 ℃, the heat preservation time is 30min, and the furnace is cooled. Carrying out phosphating treatment after annealing;
(3) and quenching and tempering the rolled steel pipe to obtain a finished pipe. Preheating for one time before quenching, wherein the preheating temperature is 800 ℃, and the heat preservation time is 10 min. The quenching temperature is 1040 ℃, the heat preservation time is 20min, and the cooling mode is air cooling. Tempering temperature is 760 ℃, heat preservation time is 60min, and cooling mode is air cooling;
(4) cutting an annular sample from a finished tube, polishing two sections to a mirror surface, and performing hardness test analysis by using a Brinell hardness tester;
(5) cutting an arc-shaped sample with a central angle of 45-60 degrees from the annular sample, and observing a section microstructure by using an optical metallographic microscope;
(6) and (4) according to national standard GBT2975-2018, cutting out a mechanical sample from the finished product pipe, and performing related mechanical property test analysis by using a multifunctional tensile testing machine.
Comparative example 2
(1) Selecting a hot-rolled and annealed T91 seamless tube as a research object, wherein the specification of the tube is phi 82mm multiplied by 8.5 mm;
(2) the steel pipe is subjected to two times of cold rolling, the phosphating treatment is carried out in the middle of the two times of cold rolling, the steel pipe is subjected to deoiling treatment after rolling, and the cold rolling process comprises the following steps: the total deformation of cold rolling is 70 percent, and the deformation of the first pass rolling is 45 percent; the rolling deformation of the second pass is 35%, and annealing is not carried out between the two passes;
(3) and quenching and tempering the rolled steel pipe to obtain a finished pipe. Preheating twice before quenching: the primary preheating temperature is 500 ℃, the heat preservation time is 10min, the secondary preheating temperature is 800 ℃, and the heat preservation time is 10 min. The quenching temperature is 1040 ℃, the heat preservation time is 10min, and the cooling mode is air cooling. Tempering temperature is 760 ℃, heat preservation time is 60min, and cooling mode is air cooling;
(4) and (4) according to national standard GBT2975-2018, cutting out a mechanical sample from the finished product pipe, and performing related mechanical property test analysis by using a multifunctional tensile testing machine.
Comparative example 3
(1) Selecting a hot-rolled and annealed T91 seamless tube as a research object, wherein the specification of the tube is phi 82mm multiplied by 8.5 mm;
(2) the steel pipe is subjected to two times of cold rolling, the phosphating treatment is carried out in the middle of the two times of cold rolling, the steel pipe is subjected to deoiling treatment after rolling, and the cold rolling process comprises the following steps: the total deformation of cold rolling is 70 percent, and the deformation of the first pass rolling is 55 percent; the rolling deformation of the second pass is 26%, and annealing is not carried out between the two passes;
(3) and quenching and tempering the rolled steel pipe to obtain a finished pipe. Preheating twice before quenching: the primary preheating temperature is 500 ℃, the heat preservation time is 10min, the secondary preheating temperature is 800 ℃, and the heat preservation time is 10 min. The quenching temperature is 1040 ℃, the heat preservation time is 10min, and the cooling mode is air cooling. Tempering temperature is 760 ℃, heat preservation time is 60min, and cooling mode is air cooling;
(4) and (4) according to national standard GBT2975-2018, cutting out a mechanical sample from the finished product pipe, and performing related mechanical property test analysis by using a multifunctional tensile testing machine.
Comparative example 4
(1) Selecting a hot-rolled and annealed T91 seamless tube as a research object, wherein the specification of the tube is phi 82mm multiplied by 8.5 mm;
(2) the steel pipe is subjected to two times of cold rolling, the phosphating treatment is carried out in the middle of the two times of cold rolling, the steel pipe is subjected to deoiling treatment after rolling, and the cold rolling process comprises the following steps: the total deformation of cold rolling is 55 percent, and the deformation of the first pass rolling is 38 percent; the rolling deformation of the second pass is 26%, and annealing is not carried out between the two passes;
(3) and quenching and tempering the rolled steel pipe to obtain a finished pipe. Preheating twice before quenching: the primary preheating temperature is 500 ℃, the heat preservation time is 10min, the secondary preheating temperature is 800 ℃, and the heat preservation time is 10 min. The quenching temperature is 1040 ℃, the heat preservation time is 10min, and the cooling mode is air cooling. Tempering temperature is 760 ℃, heat preservation time is 60min, and cooling mode is air cooling;
(4) and (4) according to national standard GBT2975-2018, cutting out a mechanical sample from the finished product pipe, and performing related mechanical property test analysis by using a multifunctional tensile testing machine.
Comparative example 5
(1) Selecting a hot-rolled and annealed T91 seamless tube as a research object, wherein the specification of the tube is phi 82mm multiplied by 8.5 mm;
(2) the steel pipe is subjected to two times of cold rolling, the phosphating treatment is carried out in the middle of the two times of cold rolling, the steel pipe is subjected to deoiling treatment after rolling, and the cold rolling process comprises the following steps: the total deformation of cold rolling is 55 percent, and the deformation of the first pass rolling is 45 percent; the rolling deformation of the second pass is 20%, and annealing is not carried out between the two passes;
(3) and quenching and tempering the rolled steel pipe to obtain a finished pipe. Preheating twice before quenching: the primary preheating temperature is 500 ℃, the heat preservation time is 10min, the secondary preheating temperature is 800 ℃, and the heat preservation time is 10 min. The quenching temperature is 1040 ℃, the heat preservation time is 10min, and the cooling mode is air cooling. Tempering temperature is 760 ℃, heat preservation time is 60min, and cooling mode is air cooling;
(4) and (4) according to national standard GBT2975-2018, cutting out a mechanical sample from the finished product pipe, and performing related mechanical property test analysis by using a multifunctional tensile testing machine.
TABLE 1 hardness in the rolled state of T91 seamless tubes in different cold rolling processes
As can be seen from table 1, in example 1, the hardness of the T91 seamless tube after the first cold rolling was 203HBW, and the hardness of the seamless tube directly subjected to the second pass without annealing was 18HBW higher than that of the seamless tube subjected to the second pass after the intermediate annealing, even if the hardness was within the standard range, and it was found that the hardness of the T91 seamless tube could be improved to some extent by the two successive cold rollings without annealing. Meanwhile, when the deformation of the first pass of cold rolling is high, the hardness of the steel pipe is 236HBW, which exceeds the hardness of the steel pipe capable of being subjected to the second pass of cold rolling, and the next process cannot be carried out.
TABLE 2 mechanical properties of the finished T91 seamless tube under different processes
| Formation process | Tensile strength MPa | Yield strength MPa | Elongation percentage% | Hardness HBW |
| Example 1 | 745 | 588 | 18 | 236 |
| Example 2 | 748 | 578 | 18 | 239 |
| Example 3 | 736 | 577 | 19 | 235 |
| Example 4 | 744 | 590 | 18 | 237 |
| Example 5 | 741 | 589 | 18 | 233 |
| Example 6 | 741 | 578 | 19 | 229 |
| Example 7 | 739 | 592 | 18 | 231 |
| Example 8 | 737 | 587 | 18 | 232 |
| Comparative example 1 | 689 | 531 | 20 | 215 |
| Comparative example 2 | 632 | 492 | 17 | 201 |
| Comparative example 3 | / | / | / | / |
| Comparative example 4 | 661 | 543 | 23 | 203 |
| Comparative example 5 | 668 | 537 | 21 | 211 |
Description of the drawings: the hardness of the second pass in table 1 is the as-rolled hardness, and the hardness in table 2 is the hardness of the finished pipe (steel pipe obtained after cold rolling + heat treatment).
In comparative example 3, the hardness of the steel is too high due to too large deformation of the first pass, so that the steel cannot meet the requirement of continuous rolling on the one hand, and on the other hand, the steel exceeds the range which can be borne by a rolling mill, and the service life of equipment is influenced by forced rolling, so that the steel cannot be rolled for the second pass, a finished pipe cannot be obtained, and the test cannot be carried out.
In table 2, comparing various performances of the T91 finished pipes obtained by different processes, it can be seen that, compared with the finished pipes obtained by the conventional production process, the tensile strength of the finished pipes obtained by the cold rolling and quenching tempering treatment for two continuous times without annealing is improved by 55-60 MPa, the yield strength is improved by 45-60 MPa, the hardness is improved by 11-15 HBW, and the plasticity is not significantly reduced. Therefore, the finished pipe obtained by omitting intermediate annealing, carrying out two continuous cold rolling and subsequent quenching and tempering treatments can obviously improve the comprehensive mechanical properties, particularly the tensile strength and the hardness of the T91 finished pipe. Meanwhile, comparative examples 4 and 5 show that when the deformation is less than the range of the present invention, the comprehensive performance of the finished pipe is significantly reduced compared with the conventional process and the process of example 1.
Comparing fig. 1 to fig. 5, it can be found that the T91 finished product tube obtained by omitting intermediate annealing, performing two continuous cold rolling and subsequent quenching and tempering treatments has finer and more uniform crystal grains, and precipitates and disperses a second phase more than that of the finished product tube obtained by the conventional generation process and is uniformly distributed, so that the second phase strengthening effect is achieved, the comprehensive mechanical property of the steel can be remarkably improved, the result is consistent with the changes of tensile strength and hardness in table 2, and the reliability of the result is further proved.
From fig. 6 to fig. 10, it can be seen that when the cold rolling deformation amount meets the scope of the present invention, no crack is found in the flattening test of the finished tube, which indicates that the cold deformation process meets the production requirements; when the deformation of the second pass of cold rolling is larger than the range of the invention, microcracks are possibly formed on the surface of the steel pipe, the cracks are expanded after quenching and tempering treatment, and obvious cracks can be found through a flattening test, thus the performance of the finished pipe is seriously influenced.
In light of the foregoing description of the preferred embodiment of the present invention, many modifications and variations will be apparent to those skilled in the art without departing from the spirit and scope of the invention. The technical scope of the present invention is not limited to the content of the specification, and must be determined according to the scope of the claims.
Claims (6)
1. A production method for improving comprehensive mechanical properties of a T91 seamless steel pipe is characterized by comprising the following steps: the method comprises the following process steps:
(1) selecting a hot-rolled and annealed T91 seamless steel tube as a research object;
(2) carrying out cold rolling twice on the steel pipe, carrying out phosphating treatment in the middle of the cold rolling twice, and carrying out deoiling treatment on the steel pipe after rolling;
(3) and quenching and tempering the rolled steel pipe to obtain the finished T91 seamless steel pipe.
2. The production method for improving the comprehensive mechanical property of the T91 seamless steel tube according to claim 1, wherein the production method comprises the following steps: the specification of the steel pipe in the step (1) is phi 82mm multiplied by 8.5 mm.
3. The production method for improving the comprehensive mechanical property of the T91 seamless steel tube according to claim 1, wherein the production method comprises the following steps: the cold rolling process in the step (2) comprises the following steps: the first-pass rolling deformation is 40-50%; the rolling deformation of the second pass is 22-26%, annealing is not carried out between the two passes, and the total deformation of the cold rolling is 60-65%.
4. The production method for improving the comprehensive mechanical property of the T91 seamless steel tube according to claim 1, wherein the production method comprises the following steps: the phosphating treatment in the step (2) comprises the following steps: putting the steel pipe into a phosphating solution at the temperature of 50-70 ℃ for soaking for 30-40 min, wherein the mass ratio of the phosphating solution to water is 1: 10; the degreasing treatment comprises the steps of cleaning the surface and the inner wall of a rolled steel pipe by using an alkaline metal degreasing and degreasing powder aqueous solution, and removing grease and oil stains on the surface and the inner wall, wherein the mass ratio of degreasing powder to water is 1: 5.
5. the production method for improving the comprehensive mechanical property of the T91 seamless steel tube according to claim 1, wherein the production method comprises the following steps: and (3) preheating twice before quenching, wherein the primary preheating temperature is 500-600 ℃, the heat preservation time is 10min, the secondary preheating temperature is 800-850 ℃, and the heat preservation time is 10 min.
6. The production method for improving the comprehensive mechanical property of the T91 seamless steel tube according to claim 5, wherein the production method comprises the following steps: the quenching process comprises the following steps: the temperature is 1040-1060 ℃, the heat preservation time is 10min, and the cooling mode is air cooling; the tempering process comprises the following steps: the temperature is 760-780 ℃, the heat preservation time is 60min, and the cooling mode is air cooling.
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Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102260840A (en) * | 2011-07-26 | 2011-11-30 | 北京科技大学 | Short-flow efficient production method for brass tubes |
| CN102581555A (en) * | 2012-02-21 | 2012-07-18 | 衡阳华菱钢管有限公司 | P91 seamless steel pipe and method for manufacturing same |
| CN103801907A (en) * | 2013-12-14 | 2014-05-21 | 青岛星晨机床有限公司 | Method for machining cylinder tube of oil cylinder |
| CN103962411A (en) * | 2013-01-31 | 2014-08-06 | 宝钢特钢有限公司 | GH3600 alloy fine thin-walled seamless pipe manufacturing method |
| CN105441829A (en) * | 2016-01-11 | 2016-03-30 | 宝银特种钢管有限公司 | 08X18H10T stainless steel seamless steel tube for steam generator |
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Patent Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102260840A (en) * | 2011-07-26 | 2011-11-30 | 北京科技大学 | Short-flow efficient production method for brass tubes |
| CN102581555A (en) * | 2012-02-21 | 2012-07-18 | 衡阳华菱钢管有限公司 | P91 seamless steel pipe and method for manufacturing same |
| CN103962411A (en) * | 2013-01-31 | 2014-08-06 | 宝钢特钢有限公司 | GH3600 alloy fine thin-walled seamless pipe manufacturing method |
| CN103801907A (en) * | 2013-12-14 | 2014-05-21 | 青岛星晨机床有限公司 | Method for machining cylinder tube of oil cylinder |
| CN105441829A (en) * | 2016-01-11 | 2016-03-30 | 宝银特种钢管有限公司 | 08X18H10T stainless steel seamless steel tube for steam generator |
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