CN114480818A - Heat treatment method of seamless mother pipe of mechanical composite pipe for acid environment - Google Patents

Heat treatment method of seamless mother pipe of mechanical composite pipe for acid environment Download PDF

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CN114480818A
CN114480818A CN202111612445.1A CN202111612445A CN114480818A CN 114480818 A CN114480818 A CN 114480818A CN 202111612445 A CN202111612445 A CN 202111612445A CN 114480818 A CN114480818 A CN 114480818A
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percent
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pipe
temperature
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CN114480818B (en
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李艳
刘金国
丛国元
张哲平
刘江成
赵兴亮
赵春辉
张国柱
赵苏娟
陈燕
胡希达
张传友
张家森
王浦
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Tianjin Steel Tube Manufacturing Co ltd
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Tianjin Steel Tube Manufacturing Co ltd
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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
    • C21D9/00—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor
    • C21D9/08—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor for tubular bodies or pipes
    • C21D9/085—Cooling or quenching
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
    • C21D1/00—General methods or devices for heat treatment, e.g. annealing, hardening, quenching or tempering
    • C21D1/18—Hardening; Quenching with or without subsequent tempering
    • 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
    • C21D11/00—Process control or regulation for heat treatments
    • C21D11/005—Process control or regulation for heat treatments for cooling
    • 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
    • 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
    • C21D9/00—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor
    • C21D9/08—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor for tubular bodies or pipes
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/02—Ferrous alloys, e.g. steel alloys containing silicon
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/04—Ferrous alloys, e.g. steel alloys containing manganese
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/06—Ferrous alloys, e.g. steel alloys containing aluminium
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
    • C22C38/40—Ferrous alloys, e.g. steel alloys containing chromium with nickel
    • C22C38/42—Ferrous alloys, e.g. steel alloys containing chromium with nickel with copper
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
    • C22C38/40—Ferrous alloys, e.g. steel alloys containing chromium with nickel
    • C22C38/44—Ferrous alloys, e.g. steel alloys containing chromium with nickel with molybdenum or tungsten
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
    • C22C38/40—Ferrous alloys, e.g. steel alloys containing chromium with nickel
    • C22C38/46—Ferrous alloys, e.g. steel alloys containing chromium with nickel with vanadium
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
    • C22C38/40—Ferrous alloys, e.g. steel alloys containing chromium with nickel
    • C22C38/48—Ferrous alloys, e.g. steel alloys containing chromium with nickel with niobium or tantalum
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
    • C22C38/40—Ferrous alloys, e.g. steel alloys containing chromium with nickel
    • C22C38/58—Ferrous alloys, e.g. steel alloys containing chromium with nickel with more than 1.5% by weight of manganese

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Abstract

The invention relates to a heat treatment method of a seamless main pipe of a mechanical composite pipe for an acid environment, which comprises the following steps: heating a high-temperature walking beam, descaling with high-pressure water, quenching at high temperature, tempering at high temperature, descaling with high-pressure water, straightening at high temperature, and air cooling in a whole cooling bed; the mother pipe comprises the following components in percentage by weight: c is more than or equal to 0.06 percent and less than or equal to 0.12 percent; si is more than or equal to 0.10 percent and less than or equal to 0.30 percent; mn is more than or equal to 1.00 percent and less than or equal to 1.60 percent; nb is more than or equal to 0.02 percent and less than or equal to 0.10 percent; v is more than or equal to 0.04 percent and less than or equal to 0.10 percent; ni and Mo are less than or equal to 0.20 percent; cr + Cu is less than or equal to 0.20 percent; other elements and balance Fe; the pipeline pipe and the main pipe can achieve high dimensional accuracy, high performance stability, high toughness (the ductile-brittle transition temperature is less than or equal to minus 60 ℃), high ductility (the elongation is more than or equal to 30 percent (plate)), and high SSC corrosion resistance (90 percent of AYS is not broken after being bent at four points for 720 hours).

Description

Heat treatment method of seamless mother pipe of mechanical composite pipe for acid environment
Technical Field
The invention belongs to the technical field of pipe preparation heat treatment, and particularly relates to a heat treatment method of a seamless mother pipe of a mechanical composite pipe in an acidic environment.
Background
With the continuous bad conditions of oil and gas exploitation and transportation, the more complex the oil and gas exploitation and transportation, the increasing demand for composite pipes. The composite pipe is characterized in that the base material is a carbon steel pipe, the composite layer is 316L stainless steel or duplex stainless steel or nickel-based alloy, the base pipe ensures basic strength, and the composite layer ensures enough corrosion allowance, so that the use requirement of a conveying environment in a severe environment is met. Compared with the common pipeline pipe, the seamless mother pipe of the composite pipe has particularity, the requirements on the stable components, the performance fluctuation (the difference between the maximum yield strength and the minimum yield strength) and the size fluctuation (the uneven wall thickness and the diameter difference between pipes) of the mother pipe are higher than those of the common pipeline pipe, the performance change of each steel pipe after the composite is required to be ensured to meet the requirements, and the uniform and stable components ensure that the performance difference between the pipes after the composite is small. The main pipe has higher requirements on the outer diameter, the wall thickness and the ovality of the whole pipe, and particularly the size of the pipe end needs to ensure that the high size precision of the pipe end meets the control of the subsequent surfacing welding and the control of the welding butt joint size. The common pipeline main pipe has the performance strength range of 150MPa, the marine pipe has the strength range of 120MPa, and the pipe end size precision can not meet the butt joint residual height difference of 0.5mm after welding. In the product standard of steel pipes, there are various requirements for steel pipes, and the mechanical properties thereof are one of the main indexes. In addition, the method also comprises the use performance, the process performance, the metallographic structure and the like, all of the requirements are closely related to the heat treatment process, and the purpose of the heat treatment is to enable the performance to reach the standard requirements.
The steel pipe heat treatment process comprises the procedures of steel pipe heating, quenching and cooling, reheating, tempering, cooling and the like, but different furnace types, heating control, quenching modes and cooling control can influence the overall performance of a final product, and the influence is more obvious particularly on a pipeline with a large caliber and a thick wall. The quenching process is a process for rapidly cooling the workpiece from high temperature to low temperature, and the characteristics of the process determine that the workpiece is deformed after quenching, especially slender products such as steel pipes are easier to deform, especially the steel pipes are bent and become waste products when the steel pipes are bent seriously. In order to solve the problem, equipment manufacturing enterprises develop various quenching devices for production, such as immersion type quenching devices, external spraying quenching devices, rotary type quenching devices, internal spraying quenching devices, external spraying quenching devices, immersion type quenching devices, external spraying quenching devices and the like to increase cooling strength, improve cooling uniformity, and achieve small deformation and improved performance after quenching. The furnace temperature and the beat are important parameters for austenitizing the steel pipe, determine the heating time of the steel pipe in the furnace and ensure that the steel pipe meets the requirements of specified temperature and heat preservation time.
For example, Chinese patents and the like are all common acidic pipelines, and have no requirements of composite pipe mother pipe indexes such as composition fluctuation (delta C, delta Si, delta Mn, delta Nb, delta V, delta Mo, delta Cr, delta Ni, delta Cu and the like), performance fluctuation (difference between maximum yield strength and minimum yield strength) and size fluctuation (wall thickness unevenness, difference between pipe diameter and pipe diameter).
Disclosure of Invention
In order to solve the problems in the prior art, the invention aims to provide a heat treatment method of a composite pipe mother pipe for an acid environment, so as to meet mechanical composite pipe mother pipes required by the development of a severe environment such as deep sea and solve the problems that the performance of a pipeline pipe is unstable and the pipeline pipe cannot meet the design requirements due to improper size in the case of mechanical composite.
The technical problem to be solved by the invention is realized by adopting the following technical scheme:
the heat treatment method of the seamless mother pipe of the mechanical composite pipe for the acid environment comprises the following steps:
heating a high-temperature walking beam, descaling with high-pressure water, quenching at high temperature, tempering at high temperature, descaling with high-pressure water, straightening at high temperature, and air cooling in a whole cooling bed.
Furthermore, the high-temperature walking beam furnace, the double-cross amplitude limiting ratio control mode and the micro-positive pressure reducing atmosphere are adopted for heating the high-temperature walking beam, and the control pressure is less than or equal to 10 Pa.
Further, the high-temperature quenching adopts an external spraying and internal spraying rotation type, and the quenching cooling medium adopts industrial water, wherein the water temperature is lower than 30 ℃, and the external spraying water amount is more than or equal to 1300m3The pressure is 2-3 bar; the inner water spraying amount is more than or equal to 700m3The pressure is 5-7 bar, and the flow velocity of water during internal spraying can reach 7-20 m/s.
Further, high-pressure water dephosphorization is respectively carried out before high-temperature quenching and after high-temperature tempering, and the pressure of descaling water is 10-22 MPa.
Furthermore, a walking beam tempering furnace is adopted for high-temperature tempering, a sub-high-speed burner is adopted for a combustion system, burning of the burner is controlled through pulses, and tempering heat preservation time is more than or equal to 15 min.
Further, the seamless mother pipe of the mechanical composite pipe for the acid environment comprises the following components in percentage by weight:
0.06％≤C≤0.12％；
0.10％≤Si≤0.30％；
1.00％≤Mn≤1.60％；
0.02％≤Nb≤0.10％；
0.04％≤V≤0.10％；
Ni+Mo≤0.20％；
Cr+Cu≤0.20％；
other elements and balance Fe.
Further, the fluctuation range of the components in the main pipe is as follows: delta C is less than or equal to 0.03 percent, delta Si is less than or equal to 0.15 percent, delta Mn is less than or equal to 0.40 percent, delta Nb is less than or equal to 0.020 percent, delta V is less than or equal to 0.030 percent, delta Mo is less than or equal to 0.05 percent, delta Cr is less than or equal to 0.05 percent, delta Ni is less than or equal to 0.10 percent, and delta Cu is less than or equal to 0.10 percent.
Furthermore, the unevenness of the wall thickness of the main pipe is less than or equal to 20 percent, the tolerance of the inner diameter of the pipe end is less than or equal to +/-1 mm, the out-of-roundness is less than or equal to 3mm, and the diameter difference of the outer diameter of the pipe end of any two steel pipes is less than or equal to 1.6 mm.
Furthermore, the performance of the mother pipe meets the requirements that the yield strength is more than or equal to 450MPa, the tensile strength is more than or equal to 535MPa, the elongation after fracture is more than or equal to 22 percent, the maximum total elongation is more than or equal to 8 percent, the yield ratio is less than or equal to 0.90, the ductile-brittle transition temperature is less than or equal to minus 60 ℃, and the strength fluctuation is less than or equal to 80 MPa.
Further, the other elements include Al, B, P, S.
Further, the weight percentages of the components in the other elements meet the following requirements: al is less than or equal to 0.050 percent; b is less than or equal to 0.0005 percent, P is less than or equal to 0.020 percent, and S is less than or equal to 0.008 percent.
The invention mainly considers the control range of components, namely the control of the fluctuation range of elements, in the aspect of component design, and ensures the basic strength range by utilizing the control of low-carbon V + Nb microalloy and texture. In the rolling process, a high-precision continuous rolling unit is utilized to ensure the external diameter, the wall thickness unevenness and the internal and external surface quality by optimizing a hole pattern matching rolling tool, so that the coincidence of the dimensional precision and the surface quality of the steel pipe is realized. In the heat treatment process, the long material heat treatment process is optimized through quenching and tempering, the full temperature control precision and hardenability and the stability of structure transformation are ensured, and the dimensional precision and the performance stability of the heat-treated material are realized.
The invention has the advantages and positive effects that:
the heat treatment method of the mechanical composite pipeline pipe main pipe for the acid environment can enable the main pipe to achieve high dimensional accuracy (the inner diameter of a pipe end is +/-1 mm, the ovality is less than or equal to 3mm, and the diameter difference between pipes is less than or equal to 1.6mm), high performance stability (the strength fluctuation range is less than or equal to 80MPa), high toughness (the ductile-brittle transition temperature is less than or equal to-60 ℃), high ductility (the elongation is more than or equal to 30 percent (plate)), and high SSC corrosion resistance (90 percent AYS is not broken after being bent for 720 hours at four points).
Drawings
The technical solutions of the present invention will be described in further detail below with reference to the accompanying drawings and examples, but it should be understood that these drawings are designed for illustrative purposes only and thus do not limit the scope of the present invention. Furthermore, unless otherwise indicated, the drawings are intended to be illustrative of the structural configurations described herein and are not necessarily drawn to scale.
FIG. 1 shows the performance fluctuation of a mechanical composite pipe seamless mother pipe for an acidic environment, which is provided by an embodiment of the invention, within 360 degrees of the whole circumference;
FIG. 2 is a photograph of a seamless mother pipe of a mechanical composite pipe for an acidic environment according to an embodiment of the present invention, which is magnified 500X.
Detailed Description
First, it should be noted that the specific structures, features, advantages, etc. of the present invention will be specifically described below by way of example, but all the descriptions are for illustrative purposes only and should not be construed as limiting the present invention in any way. Furthermore, any single feature described or implicit in any embodiment or any single feature shown or implicit in any drawing may still be combined or subtracted between any of the features (or equivalents thereof) to obtain still further embodiments of the invention that may not be directly mentioned herein. In addition, for the sake of simplicity, the same or similar features may be indicated in only one place in the same drawing.
In the description of the present invention, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc. indicate orientations or positional relationships based on the orientations or positional relationships shown in the drawings or the orientations or positional relationships that the products of the present invention are conventionally placed in use, and are only used for convenience in describing the present invention and simplifying the description, but do not indicate or imply that the devices or elements referred to must have a specific orientation, be constructed and operated in a specific orientation, and thus, should not be construed as limiting the present invention.
It should be noted that the embodiments and features of the embodiments in the present application may be combined with each other without conflict.
The heat treatment method of the seamless mother pipe of the mechanical composite pipe for the acid environment, provided by the embodiment, comprises the following steps: heating a high-temperature walking beam, descaling with high-pressure water, quenching at high temperature, tempering at high temperature, descaling with high-pressure water, straightening at high temperature, and air cooling in a whole cooling bed.
Wherein, the high-temperature walking beam furnace is adopted for heating the high-temperature walking beam, a double-cross amplitude limiting proportion control mode is adopted, the micro-positive pressure is adopted for reducing atmosphere, and the control pressure is less than or equal to 10 Pa; high temperature walking beam furnace is divided into heating section and heat preservation section along stove length direction, and every section can be divided into a plurality of districts again and burns, temperature control, can divide into 3 burning, temperature control sections if the heating section for the temperature of heating section keeps more stable, can divide into 3 burning, temperature control section if the heat preservation section again, makes the temperature of heat preservation section keep more stable, thereby guarantees the temperature homogeneity of steel pipe on length direction. The top of the charging end is pressed down, a burner is not installed, and the steel pipe which is just fed into the furnace is preheated, so that the steel pipe is prevented from being suddenly impacted by hot air flow to generate deformation. The high-temperature walking beam furnace adopts a sub-high-speed burner to supply heat, the highest temperature in the furnace is 1100 ℃, the maximum deviation of the furnace temperature of the heating section of the high-temperature walking beam is +/-20 ℃, the maximum deviation of the furnace temperature of the heat preservation section is +/-10 ℃, in order to ensure the uniform temperature in the furnace, the furnace pressure is controlled to be in a micro-positive pressure state in the normal production process, the normal pressure is 3-5Pa, and the control pressure is less than or equal to 10Pa, so that the external air is prevented from entering the furnace. The automatic control is adopted in temperature control and stepping during normal production, the automatic control can be changed into manual control when equipment is abnormal, the gas and air output quantity is manually adjusted according to the temperature deviation during the manual control, the purpose that the temperature is controlled in the process requirement range is achieved, the temperature of a plurality of district hearths at the same section of the heating section and the heat preservation section is as close as possible, and the overlarge temperature fluctuation is avoided. The temperature change of the side walls of the high-low temperature furnace should be strictly monitored in the production process, so that the temperature difference of the two side walls of the heating section of the high-low temperature furnace is ensured to be less than or equal to 30 ℃, and the temperature difference of the two side walls of the heat preservation section is ensured to be less than or equal to 15 ℃. If the situation is exceeded, appropriate measures are taken as soon as possible to enable the device to be recovered to be normal. The air excess coefficient of the high-temperature and low-temperature furnace is set as follows: the heating section 1.2 and the heat preservation section 1.0 can be adjusted according to the actual combustion condition. Adjusting the combustion ratio of air to natural gas: under the condition of ensuring normal combustion, properly regulating, regulating the flame of the high-low temperature furnace to dark red (the air excess coefficient heating section is controlled to be 0.8-2.0, the heat preservation section is controlled to be 0.8-1.5, reducing excess oxygen, and in the normal continuous production process, the residual oxygen content of the high-low temperature furnace is controlled to be below 13%, and in the process of discharging the steel pipe from the high-temperature furnace to the furnace door and opening the steel pipe to the water quenching, when the steel pipe is in fault, stagnation or can not be automatically quenched, the quenching is considered to be abnormal, and the high-temperature furnace needs to be removed and reloaded The quenching cooling medium adopts industrial water (the water temperature is lower than 30 ℃), the external water spray amount is more than or equal to 1300m3/h, and the pressure is 2-3 bar; the internal water spraying amount is more than or equal to 700m3/h, the pressure is 5-7 bar, and the flow speed of water during internal spraying can reach 7-20 m/s. And adjusting a water quenching nozzle, wherein before spray quenching, the distance between a pipe end and the nozzle is ensured within the range of 150 mm. Different steel pipes are matched with different nozzles, so that internal spray cooling water can completely enter the pipes, the nozzles are consistent with the central lines of the steel pipes, in order to ensure that the internal spray water can be sprayed into the pipes, the diameter of each nozzle is smaller than the inner diameter of each steel pipe, water flow enters the pipes and is in contact with the inner wall, the pipe ends can be fully cooled, if the distance between each nozzle and each pipe end is too short, the inner wall of the end part of each steel pipe cannot be in contact with the water, the end part quenching effect is affected, residual water is arranged on the inner surface of each steel pipe after water quenching is finished, enough water control time is ensured, accumulated water on the inner surface is completely discharged, and the residual water is prevented from entering a tempering furnace to form water vapor, so that excessive iron scales are formed on the inner surface;
in addition, high-pressure water descaling devices are installed at discharging positions of the quenching furnace and the high-temperature tempering furnace, the pressure of the descaling water is adjusted to be 10-22 MPa, the scale on the outer surface is removed, the quality of the outer surface is improved, the high-pressure water descaling devices are reasonably adjusted, and appropriate descaling links are selected according to different specifications.
In the embodiment, the walking beam tempering furnace is adopted for heating the high-temperature walking beam, the combustion system adopts a sub-high-speed burner, the burning of the burner is controlled through pulses, the tempering heat preservation time is not less than 15min, the steel pipe needs to be subjected to high-temperature tempering in the low-temperature furnace after quenching, the tempering process is very important, and the final mechanical property index of the product is directly influenced, so that the accuracy and the stability of the temperature are very important for the walking beam tempering furnace, and the basis for measuring the quality of the tempering furnace is also provided. The walking beam tempering furnace combustion system adopts a sub-high speed burner, and the burning of the burner is controlled by pulse. The tempering furnace is divided into a first heating section, a second heating section and a heat preservation section along the length direction of the furnace, each section is divided into three areas for combustion and temperature control, nine control areas are calculated, the rhythm of the tempering furnace is basically the same as that of the high-temperature furnace, and in production, the rhythm of the low-temperature furnace can be slightly lower than that of the high-temperature furnace in order to avoid the influence of certain factors on the rhythm of the high-temperature furnace, because if the rhythm of the high-temperature furnace is influenced, the furnace temperature fluctuates and the heating quality is influenced.
The mechanical composite pipe seamless main pipe for the acid environment comprises the following components in percentage by weight:
0.06％≤C≤0.12％；
0.10％≤Si≤0.30％；
1.00％≤Mn≤1.60％；
0.02％≤Nb≤0.10％；
0.04％≤V≤0.10％；
Ni+Mo≤0.20％；
Cr+Cu≤0.20％；
other elements and balance Fe.
Wherein the other elements include Al, B, P, S; the weight percentage of the components in the other elements meets the following requirements: al is less than or equal to 0.050 percent; b is less than or equal to 0.0005 percent, P is less than or equal to 0.020 percent, and S is less than or equal to 0.008 percent.
In addition, CEpcm≤0.21％；
Wherein, CEPcmThe formula is C + Si/30+ Mn/20+ Cu/20+ Ni/60+ Cr/20+ Mo/15+ V/10+5B, wherein each element represents the mass percent of the element.
Specifically, the chemical composition in the mother tube is illustrated as follows:
c: the content of the strength element is limited within the range of 0.06-0.12% by considering the influence of welding performance, smelting cost and carbon content on performance and carbon equivalent, and the fluctuation range is controlled to be less than or equal to 0.03% at delta C;
si: the strength element considers the toughness, corrosion resistance and the influence on the performance and carbon equivalent, so the content of the strength element is limited within the range of 0.10-0.30 percent, and the fluctuation range is controlled to be less than or equal to 0.15 percent;
mn: the content of the strength element is limited within the range of 1.00-1.60% by considering the strength, the low-temperature toughness and the influence on the performance and the carbon equivalent, and the fluctuation range is controlled to be less than or equal to 0.40% of delta Mn;
nb: microalloying elements, refining crystal grains and improving the corrosion resistance. Therefore, the content of the Nb-containing material is limited within the range of 0.020-0.100%, and the fluctuation range is controlled to be less than or equal to 0.020% of Delta Nb;
v: micro-alloy elements are precipitated and strengthened to improve the strength of the steel and influence on the performance and the carbon equivalent, the content of V is controlled within the range of 0.040-0.100%, and the fluctuation range is controlled within the range of delta V being less than or equal to 0.030%;
cr, Mo, Ni, Cu: residual elements participate in the calculation of carbon equivalent, and Ni + Mo is controlled to be less than or equal to 0.20 percent, and Cr + Cu is controlled to be less than or equal to 0.20 percent; the fluctuation range is controlled to be less than or equal to 0.05 percent of delta Mo, less than or equal to 0.05 percent of delta Cr, less than or equal to 0.10 percent of delta Ni and less than or equal to 0.10 percent of delta Cu;
al: al is a deoxidizing element, and the content of Al cannot be too high, so that oxide inclusion is easily caused, and the content of Al is limited to be less than or equal to 0.050 percent;
b: residual elements, the surface quality and the welding performance of the steel are considered, and the content of the residual elements is controlled within the range of less than or equal to 0.0005 percent;
p, S: p and S are impurity elements, the content of the impurity elements is reduced as much as possible in the steelmaking process, and the content of the impurity elements is controlled to be less than or equal to 0.020 percent of P and less than or equal to 0.008 percent of S.
The non-uniformity of the wall thickness of the main pipe is less than or equal to 20 percent, the ovality is less than or equal to 1 percent D, the tolerance of the inner diameter of the pipe end is less than or equal to +/-1 mm, the out-of-roundness is less than or equal to 3mm, and the diameter difference of the outer diameter of the pipe end of any two steel pipes is less than or equal to 1.6 mm; the method is realized by PQF and MPM high-precision rolling and controlled rolling processes, and the pipe end size can be realized by a direct rolling or sizing process.
The performance of the mother pipe meets the requirements that the yield strength is more than or equal to 450MPa, the tensile strength is more than or equal to 535MPa, the elongation after fracture is more than or equal to 22 percent, the maximum total elongation is more than or equal to 8 percent, the yield ratio is less than or equal to 0.90, the ductile-brittle transition temperature is less than or equal to minus 60 ℃, and the strength fluctuation is less than or equal to 80 MPa; the method is realized through a heat treatment process, wherein the heat treatment process adopts high-temperature quenching and high-temperature tempering processes, a quenching cooling medium adopts water quenching, and a high-temperature tempering cooling mode adopts air cooling.
The seamless mother pipe of the mechanical composite pipe for the acid environment, which is obtained by the heat treatment method, has the performances that the yield strength is more than or equal to 450MPa, the tensile strength is more than or equal to 535MPa, the elongation after fracture is more than or equal to 22 percent, the maximum total elongation is more than or equal to 8 percent, the yield ratio is less than or equal to 0.90, the ductile-brittle transition temperature is less than or equal to minus 60 ℃, and the strength fluctuation is less than or equal to 80 MPa. The upper roller of the straightener is provided with a quick opening mechanism, so that the end part of the steel pipe can be prevented from being damaged by collision, the special roller shape design ensures that the steel pipe is in good contact with the roller surface, the straightness of the steel pipe can meet the standard requirement, and the ovality can be further improved. The angle of the straightening roller is properly adjusted, the steel pipe and the surface of the roller are in contact with each other, the contact line is as long as possible (2/3 of the curve of the roller is preferred), the steel pipe is centered relative to the straightening roller, and the surface of the straightened steel pipe has no obvious spiral line or indentation. The height (roll gap) is adjusted to be moderate, and the straightening speed is proper; different bending is applied to steel pipes with different specifications and steel grades, the different bending is realized by adjusting the common ascending height of the middle pair of rollers, the contact surface is as large as possible, the coaxiality of the contact surface is noticed, whether the roller is stably discharged from the tail part of the pipe is noticed, the measurement during trial correction is carried out, the straightness is directly detected by a flat ruler or a special measuring tool with proper length, the outer diameter or the inner diameter and the out-of-roundness are detected by a vernier caliper or a set ruler, the steel pipes can be put into operation formally when the indexes reach the standard requirements, and the reasonable pressing amount of a straightening machine is adjusted during straightening to deform the steel pipes so that iron oxide scales on the inner surface fall off.
By way of example, in this example, several DNVGL SMLS 450SFPDU steel grade, 219.1mm by 12.7mm specification mechanical composite seamless pipe for acidic environment was prepared, the chemical composition of which is as follows in tables 1, 2; the dimensional accuracy of the tube is shown in table 3, the tube end of this example was obtained directly by rolling, without additional machining; the mechanical stability properties are shown in Table 4; the ductile-brittle transition series is shown in Table 5, and the transition temperature is less than or equal to-60 ℃.
TABLE 1 line pipe chemistry
Figure BDA0003435420230000111
Note: ni, Cr, Mo and Cu are smelting residues of the electric furnace, and elements are added unintentionally;
the chemical composition of the line pipe contains other impurity elements, as shown in table 2:
TABLE 2
Ca Pb Sn As Sb Bi O N H
0.0010 0.0001 0.0048 0.0056 0.0021 0.0005 0.0018 0.0050 0.00002
TABLE 3 line pipe dimensional tolerance case
Figure BDA0003435420230000112
Note: the diameter difference between the pipes is obtained by comparing the outer diameters of the pipe ends of any two steel pipes according to the actually measured outer diameters of the pipe ends of the steel pipes.
TABLE 4 mechanical Properties of line pipes
Figure BDA0003435420230000121
Note: the sample type is a plate-shaped sample, bo is the sample width, and Lo is the sample gauge length of 50 mm; rt 0.5: specifying a total elongation strength; rm: resist against
Tensile strength; a: elongation after fracture; agt: maximum force total elongation; ag: maximum force plastic elongation; Y/T: the yield ratio.
TABLE 5 ductile to brittle transition series values for line pipes
Figure BDA0003435420230000122
Figure BDA0003435420230000131
Note: k is the absorbed energy, V is the notch shape, 8 is the pendulum edge radius; t: transverse direction; AK: an impact value; SFA: percent shear area (fiber section).
It should be noted that, in fig. 1, performance fluctuation of 360 ° in the whole circumference of the seamless mother pipe of the mechanical composite pipe for an acidic environment provided by the embodiment of the present invention is obtained by sampling clockwise from No. 1 along the circumferential direction of the steel pipe, with a sample width of 70mm, taking 8 samples in total, and performing a tensile test to obtain the tensile performance of each sample; the tensile property data has small size change, which shows that the property is uniform and stable; fig. 2 is a 500X photograph of the seamless mother tube structure of the mechanical composite tube for acid environment according to the embodiment of the present invention, which is a metallographic specimen of the region after heat treatment, and the structure analysis is performed by taking a photograph under a magnification of 500X.
The present invention has been described in detail with reference to the above examples, but the description is only for the preferred examples of the present invention and should not be construed as limiting the scope of the present invention. All equivalent changes and modifications made within the scope of the present invention shall fall within the scope of the present invention.

Claims (10)

1. The heat treatment method of the seamless mother pipe of the mechanical composite pipe for the acid environment is characterized by comprising the following steps:
heating a high-temperature walking beam, descaling with high-pressure water, quenching at high temperature, tempering at high temperature, descaling with high-pressure water, straightening at high temperature, and air cooling in a whole cooling bed.
2. The heat treatment method of the seamless mother pipe of the mechanical composite pipe for the acid environment according to claim 1, characterized in that: the high-temperature walking beam heating adopts a high-temperature walking beam furnace, a double-cross amplitude limiting ratio control mode and a micro-positive pressure reducing atmosphere, and the control pressure is less than or equal to 10 Pa.
3. The heat treatment method of the seamless mother pipe of the mechanical composite pipe for the acid environment according to claim 1, characterized in that: the high-temperature quenching adopts an external spraying and internal spraying rotation mode, and the quenching cooling medium adopts industrial water, wherein the water temperature is lower than 30 ℃, and the external spraying water quantity is more than or equal to 1300m3The pressure is 2-3 bar; the internal water spraying amount is more than or equal to 700m3The pressure is 5-7 bar, and the flow velocity of water during internal spraying can reach 7-20 m/s.
4. The heat treatment method of the seamless mother pipe of the mechanical composite pipe for the acid environment according to claim 1, characterized in that: and (3) removing phosphorus by high-pressure water before high-temperature quenching and after high-temperature tempering respectively, wherein the pressure of the descaling water is 10-22 MPa.
5. The heat treatment method of the seamless mother pipe of the mechanical composite pipe for the acid environment according to claim 1, characterized in that: the high-temperature tempering adopts a walking beam tempering furnace, the combustion system adopts a sub-high-speed burner, the burning of the burner is controlled through pulse, and the tempering heat preservation time is more than or equal to 15 min.
6. The heat treatment method of the seamless mother pipe of the mechanical composite pipe for the acid environment according to claim 1, characterized in that: the seamless mother pipe of the mechanical composite pipe for the acid environment comprises the following components in percentage by weight:
0.06％≤C≤0.12％；
0.10％≤Si≤0.30％；
1.00％≤Mn≤1.60％；
0.02％≤Nb≤0.10％；
0.04％≤V≤0.10％；
Ni+Mo≤0.20％；
Cr+Cu≤0.20％；
other elements and balance Fe.
7. The heat treatment method of the seamless mother pipe of the mechanical composite pipe for the acid environment according to claim 6, characterized in that: the fluctuation range of the components in the main pipe is as follows: delta C is less than or equal to 0.03 percent, delta Si is less than or equal to 0.15 percent, delta Mn is less than or equal to 0.40 percent, delta Nb is less than or equal to 0.020 percent, delta V is less than or equal to 0.030 percent, delta Mo is less than or equal to 0.05 percent, delta Cr is less than or equal to 0.05 percent, delta Ni is less than or equal to 0.10 percent, and delta Cu is less than or equal to 0.10 percent.
8. The heat treatment method of the seamless mother pipe of the mechanical composite pipe for the acid environment according to claim 1, characterized in that: the unevenness of the wall thickness of the main pipe is less than or equal to 20 percent, the tolerance of the inner diameter of the pipe end is less than or equal to +/-1 mm, the out-of-roundness is less than or equal to 3mm, and the difference of the outer diameter of the pipe end of any two steel pipes is less than or equal to 1.6 mm.
9. The heat treatment method of the seamless mother pipe of the mechanical composite pipe for the acid environment according to claim 1, characterized in that: the performance of the mother pipe meets the conditions that the yield strength is more than or equal to 450MPa, the tensile strength is more than or equal to 535MPa, the elongation after fracture is more than or equal to 22 percent, the maximum total elongation is more than or equal to 8 percent, the yield ratio is less than or equal to 0.90, the ductile-brittle transition temperature is less than or equal to minus 60 ℃, and the strength fluctuation is less than or equal to 80 MPa.
10. The heat treatment method of the seamless mother pipe of the mechanical composite pipe for the acid environment as claimed in claim 6, wherein: the other elements comprise Al, B, P and S, and the weight percentages of the components in the other elements meet the following requirements: al is less than or equal to 0.050 percent; b is less than or equal to 0.0005 percent, P is less than or equal to 0.020 percent, and S is less than or equal to 0.008 percent.
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CN101892432A (en) * 2010-07-09 2010-11-24 天津钢管集团股份有限公司 Manufacturing method of X70QS seamless line pipe for acid environment
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