CN104451100B - A kind of seamless steel pipe heat treatment method - Google Patents
A kind of seamless steel pipe heat treatment method Download PDFInfo
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- 229910000831 Steel Inorganic materials 0.000 title claims abstract description 158
- 239000010959 steel Substances 0.000 title claims abstract description 158
- 238000010438 heat treatment Methods 0.000 title claims abstract description 68
- 238000000034 method Methods 0.000 title claims abstract description 63
- 238000001816 cooling Methods 0.000 claims abstract description 16
- 238000000137 annealing Methods 0.000 claims description 37
- 230000007547 defect Effects 0.000 claims description 13
- 238000005096 rolling process Methods 0.000 claims description 9
- 238000002360 preparation method Methods 0.000 claims description 4
- 238000012545 processing Methods 0.000 claims description 3
- 238000009413 insulation Methods 0.000 claims description 2
- 238000009785 tube rolling Methods 0.000 claims 2
- 238000006392 deoxygenation reaction Methods 0.000 claims 1
- 238000005553 drilling Methods 0.000 claims 1
- 238000005488 sandblasting Methods 0.000 claims 1
- 238000004321 preservation Methods 0.000 description 16
- 238000005452 bending Methods 0.000 description 9
- 229910000797 Ultra-high-strength steel Inorganic materials 0.000 description 4
- 229910000851 Alloy steel Inorganic materials 0.000 description 3
- 238000000227 grinding Methods 0.000 description 3
- 239000002184 metal Substances 0.000 description 3
- 230000000737 periodic effect Effects 0.000 description 3
- 239000002893 slag Substances 0.000 description 3
- 230000007704 transition Effects 0.000 description 3
- 229910001566 austenite Inorganic materials 0.000 description 2
- 230000009286 beneficial effect Effects 0.000 description 2
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- 238000005516 engineering process Methods 0.000 description 2
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- 238000005259 measurement Methods 0.000 description 2
- 239000000725 suspension Substances 0.000 description 2
- NINIDFKCEFEMDL-UHFFFAOYSA-N Sulfur Chemical compound [S] NINIDFKCEFEMDL-UHFFFAOYSA-N 0.000 description 1
- 230000007423 decrease Effects 0.000 description 1
- 238000009826 distribution Methods 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 238000001125 extrusion Methods 0.000 description 1
- 238000005242 forging Methods 0.000 description 1
- 238000007689 inspection Methods 0.000 description 1
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- 239000007788 liquid Substances 0.000 description 1
- 239000000203 mixture Substances 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 238000000465 moulding Methods 0.000 description 1
- 238000005070 sampling Methods 0.000 description 1
- 239000002436 steel type Substances 0.000 description 1
- 239000000126 substance Substances 0.000 description 1
- 229910052717 sulfur Inorganic materials 0.000 description 1
- 239000011593 sulfur Substances 0.000 description 1
- 238000003466 welding Methods 0.000 description 1
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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
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Abstract
Description
技术领域technical field
本发明涉及一种无缝钢管加工工艺，具体涉及一种无缝钢管热处理方法。The invention relates to a seamless steel pipe processing technology, in particular to a seamless steel pipe heat treatment method.
背景技术Background technique
退火热处理是将钢管加热到一定温度保温一段时间，然后使它慢慢冷却。钢管的退火热处理是将钢管加热到发生相变或部分相变的温度，经由保温后缓慢冷却的热处理方法。热处理的目的是为了降低硬度、提高塑性、改善加工性能；消除内应力、稳定钢管尺寸、放置变形和开裂；细化晶粒、改善组织、提高无缝钢管的力学性能。Annealing heat treatment is to heat the steel pipe to a certain temperature and keep it for a period of time, and then let it cool slowly. The annealing heat treatment of the steel pipe is a heat treatment method in which the steel pipe is heated to a temperature at which a phase transition or partial phase transition occurs, and then slowly cooled after heat preservation. The purpose of heat treatment is to reduce hardness, improve plasticity, and improve processing performance; eliminate internal stress, stabilize steel pipe size, place deformation and cracking; refine grains, improve structure, and improve mechanical properties of seamless steel pipes.
目前无缝钢管在进行退火热处理时，在经过正常的保温后，只要通过关闭热处理炉的加热烧嘴，不再供热，钢管热随热处理炉自由温降进行完全或等温退火。在此过程中，温降过程为不可控过程。At present, when seamless steel pipes are annealed and heat treated, after normal heat preservation, as long as the heating burner of the heat treatment furnace is turned off, no heat is supplied, and the heat of the steel pipe is completely or isothermally annealed with the free temperature drop of the heat treatment furnace. In this process, the temperature drop process is an uncontrollable process.
由于无缝钢管普遍长度较长，约4～12m；因此，整个无缝钢管必将存在严重温度差异，由此带来的后果如下：Due to the generally long length of seamless steel pipes, about 4 to 12m; therefore, there must be serious temperature differences throughout the seamless steel pipes, and the resulting consequences are as follows:
1，无缝钢管因温差产生的应力而变弯；1. The seamless steel pipe is bent due to the stress caused by the temperature difference;
2，整管的力学性能差异较大。2. The mechanical properties of the whole tube are quite different.
由于一般采用的退火工艺的钢管退火时间足够长，所以虽然整个无缝钢管力学性质差异较大，但均可满足用户要求，故未受足够重视。随着用户对产品要求的提高，此种存在两端差异的钢管已难以满足用户的要求。并且温差产生的应力致使的弯曲可采用矫直的方式进行，但是，钢管管端无法矫直和部分无缝钢管没有合适的矫直机，导致产品成材率下降甚至因无法完成矫直而不能成为成品。Since the annealing time of steel pipes in the general annealing process is long enough, although the mechanical properties of the entire seamless steel pipe are quite different, they can all meet the requirements of users, so they have not been paid enough attention. With the improvement of users' requirements for products, it is difficult for such a steel pipe with two ends to meet the requirements of users. And the bending caused by the stress caused by the temperature difference can be straightened. However, the end of the steel pipe cannot be straightened and some seamless steel pipes do not have a suitable straightening machine, resulting in a decline in the yield of the product or even a failure to become a steel pipe due to the inability to complete the straightening. finished product.
发明内容Contents of the invention
[要解决的技术问题][Technical problem to be solved]
本发明的目的是解决上述现有技术存在的问题，提出一种无缝钢管热处理方法，使得无缝钢管热处理后不因温差产生的应力而变弯，增强无缝钢管的力学均匀性，进一步优化无缝钢管的制备。The purpose of the present invention is to solve the problems existing in the above-mentioned prior art, and propose a heat treatment method for seamless steel pipes, so that the seamless steel pipes will not bend due to the stress generated by temperature difference after heat treatment, enhance the mechanical uniformity of seamless steel pipes, and further optimize Preparation of seamless steel pipes.
[技术方案][Technical solutions]
为了达到上述的技术效果，本发明采取以下技术方案：In order to achieve the above-mentioned technical effect, the present invention takes the following technical solutions:
本发明通过对大口径无缝钢管进行阶梯式降温，以保证无缝钢管全长度范围内的温度差缩小，达到一般热处理要求的±10℃；从而控制热处理过程中的温降，避免无缝钢管因温差产生的应力引起无缝钢管弯曲的情况，同时保证了整个无缝钢管性能的稳定性和均匀性。The present invention lowers the temperature of the large-diameter seamless steel pipe stepwise to ensure that the temperature difference within the entire length of the seamless steel pipe is reduced, reaching ±10°C required by general heat treatment; thereby controlling the temperature drop in the heat treatment process and avoiding the temperature difference of the seamless steel pipe The stress caused by the temperature difference causes the seamless steel pipe to bend, while ensuring the stability and uniformity of the performance of the entire seamless steel pipe.
一种无缝钢管热处理方法，它包括以下步骤：A heat treatment method for seamless steel pipes, comprising the following steps:
首先，将大口径无缝钢管垂直放入加热炉中；First, put the large-diameter seamless steel pipe vertically into the heating furnace;
然后，调整加热炉的温度，使温度升高至800℃以上后，保温20～30min；接着，利用加热炉的控温系统使大口径无缝钢管按20～40℃阶梯式降温，每降低一个温度需保温20～95min；当温度降至550℃时，关闭控温系统，使大口径无缝钢管在加热炉内空冷25～35min；Then, adjust the temperature of the heating furnace so that the temperature rises above 800°C, and then keep it warm for 20-30 minutes; then, use the temperature control system of the heating furnace to lower the temperature of the large-diameter seamless steel pipe in steps of 20-40°C, and reduce the temperature by one step each time. The temperature needs to be kept warm for 20-95 minutes; when the temperature drops to 550°C, turn off the temperature control system, and make the large-diameter seamless steel pipe air-cooled in the heating furnace for 25-35 minutes;
最后，将大口径无缝钢管取出，放置于钢管台架上冷却。Finally, the large-diameter seamless steel pipe is taken out and placed on a steel pipe stand for cooling.
根据本发明的一种优选实施方式，所述的大口径无缝钢管选自Φ780×35mm或Φ356×25mm规格的无缝钢管。According to a preferred embodiment of the present invention, the large-diameter seamless steel pipe is selected from seamless steel pipes with specifications of Φ780×35 mm or Φ356×25 mm.
根据本发明的另一个优选实施方式，所述的大口径无缝钢管的制备步骤如下：According to another preferred embodiment of the present invention, the preparation steps of the large-diameter seamless steel pipe are as follows:
A，周期轧管机组轧管A. Periodic pipe rolling mill
首先取电渣钢锭进行钢锭镗孔，然后再穿孔轧制，接着退火处理后矫直，得到初品无缝钢管；First, the electroslag steel ingot is taken to bore the ingot, then pierced and rolled, and then straightened after annealing treatment to obtain the primary seamless steel pipe;
B，推制扩管B, pushing and expanding pipe
将步骤A得到的初品无缝钢管的管端进行平头处理、内表面喷砂除氧化皮和表面缺陷处理，然后将处理后的初品无缝钢管进行第一次推制扩管；The pipe end of the primary seamless steel pipe obtained in step A is subjected to flat end treatment, the inner surface is sandblasted to remove scale and surface defects, and then the processed primary seamless steel pipe is subjected to the first push expansion;
接着，对第一次推制扩管后的初品无缝钢管进行退火处理以降低钢管强度，再进行第二次推制扩管，得到所述的大口径无缝钢管。Next, annealing is performed on the primary seamless steel pipe after the first pushing and expanding to reduce the strength of the steel pipe, and then the second pushing and expanding is carried out to obtain the large-diameter seamless steel pipe.
根据本发明的另一个优选实施方式，在于在步骤A中，所述的退火方式为完全退火。According to another preferred embodiment of the present invention, in step A, the annealing method is complete annealing.
根据本发明的另一个优选实施方式，在步骤A中，所述矫直是指修磨电渣钢锭缺陷，其包括利用切除和修磨方式清除管端缺陷。According to another preferred embodiment of the present invention, in step A, the straightening refers to grinding the defects of the electroslag steel ingot, which includes removing the defects of the pipe end by means of cutting and grinding.
根据本发明的另一个优选实施方式，在步骤B中，所述第一次推制扩管的推制温度为740～760℃、推制速度为40mm/min、推制力度为12MPa；所述第二次推制扩管的推制温度为750℃、推制速度为20mm/min、推制力度为15MPa。According to another preferred embodiment of the present invention, in step B, the pushing temperature of the first pushing and expanding pipe is 740-760°C, the pushing speed is 40mm/min, and the pushing force is 12MPa; The pushing temperature for the second push and expansion is 750°C, the pushing speed is 20mm/min, and the pushing force is 15MPa.
根据本发明的另一个优选实施方式，所述的温度升高至850℃以上。According to another preferred embodiment of the present invention, said temperature is increased to above 850°C.
根据本发明的另一个优选实施方式，所述的加热炉选自室式加热炉或井式加热炉。According to another preferred embodiment of the present invention, the heating furnace is selected from a chamber heating furnace or a pit heating furnace.
根据本发明的另一个优选实施方式，所述阶梯式降温是首先将温度按30℃的梯度一步步降温至680℃；每降温30℃，保温20～30min；然后在温度降至650℃时，保温85～95min；接着，继续按每降温30～40℃，保温20～30min；直到温度降至550℃，关闭控温系统，停止阶梯式降温。According to another preferred embodiment of the present invention, the stepwise cooling is to first lower the temperature to 680°C step by step according to the gradient of 30°C; every time the temperature is lowered by 30°C, keep the temperature for 20 to 30 minutes; then when the temperature drops to 650°C, Keep warm for 85-95 minutes; then, continue to keep warm for 20-30 minutes at 30-40°C per step; until the temperature drops to 550°C, turn off the temperature control system and stop the step-wise cooling.
下面将详细地说明本发明。The present invention will be described in detail below.
一种无缝钢管热处理方法，它包括以下步骤：A heat treatment method for seamless steel pipes, comprising the following steps:
首先，将大口径垂直放入加热炉中；First, put the large diameter vertically into the heating furnace;
然后，调整加热炉无缝钢管的温度，使温度升高至800℃以上后，保温20～30min；接着，利用加热炉的控温系统使大口径无缝钢管按20～40℃阶梯式降温，每降低一个温度需保温20～95min；当温度降至550℃时，关闭控温系统，使大口径无缝钢管在加热炉内空冷25～35min；Then, adjust the temperature of the seamless steel pipe in the heating furnace so that the temperature rises above 800°C, and then keep it warm for 20-30 minutes; then, use the temperature control system of the heating furnace to make the large-diameter seamless steel pipe cool in steps at 20-40°C, When the temperature drops to 550°C, the temperature control system is turned off, and the large-diameter seamless steel pipe is air-cooled in the heating furnace for 25-35 minutes;
最后，将大口径无缝钢管取出，放置于钢管台架上冷却。Finally, the large-diameter seamless steel pipe is taken out and placed on a steel pipe stand for cooling.
一般使用的大口径无缝钢管在加热炉中的退火方式，在降温阶段降温速率不可控，由于无缝钢管较长，钢管两端在降温过程中存在较大温差，因此导致钢管因温差应力作用产生弯曲的情况；同时，无缝钢管两端因温差差异较大而力学性能差异较大。因此，为了排出这种差异的存在，突破常规退火工艺的设置，本发明设计了梯度退火工艺。该梯度退火工艺是通过在热处理降温过程中阶段保温的方式，减少了温差的影响。The annealing method of the large-diameter seamless steel pipe generally used in the heating furnace is uncontrollable in the cooling stage. Due to the long seamless steel pipe, there is a large temperature difference between the two ends of the steel pipe during the cooling process, which causes the steel pipe to be affected by the stress caused by the temperature difference. Bending occurs; at the same time, the mechanical properties of the two ends of the seamless steel pipe are greatly different due to the large temperature difference. Therefore, in order to eliminate the existence of this difference and break through the setting of the conventional annealing process, the present invention designs a gradient annealing process. The gradient annealing process reduces the influence of temperature difference by means of step-by-step heat preservation during the heat treatment cooling process.
根据本发明的一种优选实施方式，所述的大口径无缝钢管选自Φ780×35mm或Φ356×25mm规格的无缝钢管。According to a preferred embodiment of the present invention, the large-diameter seamless steel pipe is selected from seamless steel pipes with specifications of Φ780×35 mm or Φ356×25 mm.
根据本发明的另一个优选实施方式，所述的大口径无缝钢管的制备步骤如下：According to another preferred embodiment of the present invention, the preparation steps of the large-diameter seamless steel pipe are as follows:
A，周期轧管机组轧管A. Periodic pipe rolling mill
首先取电渣钢锭进行钢锭镗孔，然后再穿孔轧制，接着退火处理后矫直，得到初品无缝钢管；First, the electroslag steel ingot is taken to bore the ingot, then pierced and rolled, and then straightened after annealing treatment to obtain the primary seamless steel pipe;
电渣钢锭是指利用电流通过液态渣池渣阻热，将金属电极熔化，熔化的金属汇集成溶滴，滴落时穿过渣层进入金属熔池，然后与水冷结晶器中结晶凝固成的超高强度钢钢锭。该电渣钢锭纯度高、含硫低、非金属夹杂物少、钢锭表面光滑、洁净均匀致密、金相组织和化学成分均匀。电渣钢锭的铸态机械性能可达到或超过同钢种锻件的指标。Electroslag steel ingot refers to the use of current to pass through the liquid slag pool slag to resist heat, melt the metal electrode, and the molten metal gathers into molten droplets. When it drops, it passes through the slag layer and enters the metal molten pool, and then crystallizes and solidifies with the water-cooled crystallizer. Ingots of ultra-high-strength steel. The electroslag steel ingot has high purity, low sulfur content, less non-metallic inclusions, smooth surface of the steel ingot, clean, uniform and dense, uniform metallographic structure and chemical composition. The as-cast mechanical properties of electroslag steel ingots can reach or exceed those of forgings of the same steel type.
超高强度合金钢的变形抗力较大，钢锭镗孔时易出现内折、圈裂等缺陷。为了保证钢管内表面质量，同时也减小轧机负荷，本发明采用了钢锭镗孔后再穿孔轧制的工艺，解决了圈裂、内折问题。The deformation resistance of ultra-high-strength alloy steel is relatively large, and defects such as inner folds and ring cracks are prone to occur when the steel ingot is bored. In order to ensure the quality of the inner surface of the steel pipe and reduce the load of the rolling mill, the invention adopts the technology of piercing and rolling after the steel ingot is bored, which solves the problems of ring cracking and inner folding.
由于超高强度合金钢的钢种特性，穿孔轧制后其强度高、硬度大，因此不能直接矫直，否则钢管头尾易矫裂；同时钢管在管端常有内外折缺陷，此类缺陷在矫直时易成为裂纹起源。因此需要在矫直进行钢管完全退火，在退火后，还需要通过切除、修磨等方式清除管端缺陷。Due to the steel characteristics of ultra-high-strength alloy steel, it has high strength and high hardness after piercing and rolling, so it cannot be straightened directly, otherwise the head and tail of the steel pipe will be easily cracked; at the same time, the steel pipe often has internal and external bending defects at the pipe end. It is easy to become the origin of cracks during straightening. Therefore, it is necessary to fully anneal the steel pipe during straightening, and after annealing, it is necessary to remove the defects of the pipe end by cutting and grinding.
本发明还可以重新设计连接法兰盘并用高强螺栓的顶头顶杆连接处焊死等技术措施，成功完成钢管变形。The present invention can also redesign the connection flange and use technical measures such as high-strength bolts to weld the joints of the top and top rods, and successfully complete the deformation of the steel pipe.
B，推制扩管B, pushing and expanding pipe
将步骤A得到的初品无缝钢管的管端进行平头处理、内表面喷砂除氧化皮和表面缺陷处理，然后将处理后的初品无缝钢管进行第一次推制扩管；The pipe end of the primary seamless steel pipe obtained in step A is subjected to flat end treatment, the inner surface is sandblasted to remove scale and surface defects, and then the processed primary seamless steel pipe is subjected to the first push expansion;
由于推制工艺特点，钢管需前后接触、推挤来提供变形的动力。如果管端不平易造成挤压后不规则变形，这将严重影响变形工具的使用寿命。因此，推制扩管前需要对管端进行平头处理。Due to the characteristics of the pushing process, the steel pipe needs to be contacted and pushed back and forth to provide the power of deformation. If the pipe end is not easy to cause irregular deformation after extrusion, this will seriously affect the service life of the deformation tool. Therefore, it is necessary to flatten the pipe end before pushing and expanding the pipe.
推制是扩管工艺，经此变形后钢管表面缺陷会在原来的基础上进行放大，如浅表裂纹经推制变形后易迸裂，造成裂纹深度加深；因此需要在推制前进行表面缺陷处理。同时，推制工艺的变形主要靠推制顶头来实现，如果钢管内表面有较重氧化皮，经推制后，内壁划道情况严重，因此推制前还需将表面的氧化皮处理干净。Pushing is a pipe expansion process. After this deformation, the surface defects of the steel pipe will be enlarged on the original basis. For example, shallow cracks are easy to crack after pushing and deformation, causing the crack depth to deepen; therefore, surface defects need to be treated before pushing. . At the same time, the deformation of the pushing process is mainly realized by pushing the plug. If there is heavy scale on the inner surface of the steel pipe, the inner wall will be severely scratched after pushing. Therefore, the scale on the surface must be cleaned before pushing.
接着，对第一次推制扩管后的初品无缝钢管进行退火处理以降低钢管强度，再进行第二次推制扩管，得到所述的大口径无缝钢管。Next, annealing is performed on the primary seamless steel pipe after the first pushing and expanding to reduce the strength of the steel pipe, and then the second pushing and expanding is carried out to obtain the large-diameter seamless steel pipe.
本发明根据设备情况，设计采用两次推制成型。第一次推制过程相对稳定，推制力较高，推制温度视具体的钢管壁厚选择合适温度。温度过高钢管易产生较厚氧化铁皮，将增加后续处理工序，同时能耗较大；温度过低，则钢管的变形抗力将急剧提升，超过设备能力时将导致无法进行生产。为保证第二次推制的质量，在两次推制之间加入退火处理以降低钢管强度。第二次推制过程开始时相对稳定，速度较第一次推制慢，推制力比第一次推制力高；其主要目的是为了降低推制速度。本发明的多次推制采用中间退火以及控制合适的变形量和较低速度等工艺措施，成功解决了超高强度合金钢变形抗力大、推制困难的问题。According to the condition of the equipment, the present invention adopts two times of push molding. The first pushing process is relatively stable, and the pushing force is relatively high. The pushing temperature depends on the specific wall thickness of the steel pipe to select an appropriate temperature. If the temperature is too high, the steel pipe will easily produce thicker oxide scale, which will increase the subsequent treatment process and consume a lot of energy; if the temperature is too low, the deformation resistance of the steel pipe will increase sharply, and when it exceeds the capacity of the equipment, production will not be possible. In order to ensure the quality of the second push, an annealing treatment is added between the two pushes to reduce the strength of the steel pipe. The second push process is relatively stable at the beginning, the speed is slower than the first push, and the push force is higher than the first push force; its main purpose is to reduce the push speed. The multi-push process of the present invention adopts intermediate annealing and control of appropriate deformation and lower speed, etc., successfully solving the problems of high deformation resistance and difficult push of ultra-high-strength alloy steel.
根据本发明的另一个优选实施方式，所述的温度升高至850℃以上。According to another preferred embodiment of the present invention, said temperature is increased to above 850°C.
本发明需要升高的温度是无缝钢管的相变温度区间以上或以内的某一温度。即将温度升高至无缝钢管亚共析钢、共析钢或过共析钢以上30～50℃；保持一段时间。加热过程是无缝钢管转变为奥氏体，保温一段时间是为了使无缝钢管完全转变为奥氏体。The temperature that needs to be raised in the present invention is a certain temperature above or within the phase transition temperature range of the seamless steel pipe. That is, the temperature is raised to 30-50°C above the hypoeutectoid steel, eutectoid steel or hypereutectoid steel of seamless steel pipe; keep it for a period of time. The heating process is to transform the seamless steel pipe into austenite, and the heat preservation for a period of time is to completely transform the seamless steel pipe into austenite.
根据本发明的另一个优选实施方式，所述的加热炉选自室式加热炉或井式加热炉。According to another preferred embodiment of the present invention, the heating furnace is selected from a chamber heating furnace or a pit heating furnace.
根据本发明的另一个优选实施方式，所述阶梯式降温是首先将温度按30℃的梯度一步步降温至680℃；每降温30℃，保温20～30min；然后在温度降至650℃时，保温85～95min；接着，继续按每降温30～40℃，保温20～30min；直到温度降至550℃，关闭控温系统，停止阶梯式降温。According to another preferred embodiment of the present invention, the stepwise cooling is to first lower the temperature to 680°C step by step according to the gradient of 30°C; every time the temperature is lowered by 30°C, keep the temperature for 20 to 30 minutes; then when the temperature drops to 650°C, Keep warm for 85-95 minutes; then, continue to keep warm for 20-30 minutes at 30-40°C per step; until the temperature drops to 550°C, turn off the temperature control system and stop the step-wise cooling.
本发明参考原热处理工艺，保留了最高的保温温度、中间保温温度和最后的保温温度，并适应性增加了适量的保温温度构成相对致密的保温梯度，以减少温差，避免温差产生的影响。Referring to the original heat treatment process, the present invention retains the highest heat preservation temperature, intermediate heat preservation temperature and final heat preservation temperature, and adaptively increases an appropriate amount of heat preservation temperature to form a relatively dense heat preservation gradient, so as to reduce the temperature difference and avoid the influence of the temperature difference.
本发明每个阶段的保温时间是根据大口径无缝钢管的重量计算得来。其中间保温时间是根据实际温降过程中出现温差的情况及均匀时间，经多次测量得出。The holding time of each stage of the present invention is calculated according to the weight of the large-caliber seamless steel pipe. The intermediate holding time is based on the temperature difference and the uniform time during the actual temperature drop process, which is obtained through multiple measurements.
[有益效果][beneficial effect]
本发明与现有技术相比，具有以下的有益效果：Compared with the prior art, the present invention has the following beneficial effects:
本发明成功解决了无缝钢管热处理过程中变弯的温度，实现了钢管不矫直即满足技术协议要求。并且本发明热处理的无缝钢管性能指标完全满足技术协议要求，消除了因普通退火工艺致使无缝钢管两端性能存在的差异，保证了整个无缝钢管性能的稳定性。同时本发明避免了部分无缝钢管因热处理产生的弯曲、力学性能不均匀而无法矫直纠正的现象。The invention successfully solves the bending temperature in the heat treatment process of the seamless steel pipe, and realizes that the steel pipe meets the requirement of the technical agreement without straightening. Moreover, the performance index of the heat-treated seamless steel pipe of the present invention fully meets the requirements of the technical agreement, eliminates the difference in performance at both ends of the seamless steel pipe caused by the common annealing process, and ensures the stability of the performance of the entire seamless steel pipe. At the same time, the invention avoids the phenomenon that some seamless steel pipes cannot be straightened due to bending and uneven mechanical properties caused by heat treatment.
附图说明Description of drawings
图1为本发明实施例1大口径无缝钢管垂直悬挂的示意图；Fig. 1 is the schematic diagram of the vertical suspension of large-diameter seamless steel pipe in Embodiment 1 of the present invention;
图2为本发明常规退火工艺曲线图，其中高温段即860℃保温时间不少于90min，保温时间t1按0.25h/吨计算；650±10℃的保温时间t2按0.35h/吨计算；降温的速率为50℃/h；Fig. 2 is a curve diagram of the conventional annealing process of the present invention, wherein the high temperature section is 860 ℃ holding time is not less than 90min, holding time t1 is calculated by 0.25h/ton; 650 ± 10 ℃ holding time t2 is calculated by 0.35h/ton; cooling The rate is 50℃/h;
图3为本发明实施例1阶梯式退火工艺曲线图，其中，t1＝6h；t2～t7＝20min；t8＝90min；t9～t10＝20min；t11＝30min；Fig. 3 is the stepwise annealing process graph of embodiment 1 of the present invention, wherein, t1=6h; t2～t7=20min; t8=90min; t9～t10=20min; t11=30min;
附图标记说明如下：The reference signs are explained as follows:
1为夹持件； 3为挂钩；1 is a clamping piece; 3 is a hook;
2为挂板； 4为大口径无缝钢管。2 is a hanging plate; 4 is a large diameter seamless steel pipe.
具体实施方式detailed description
下面结合本发明的实施例对本发明作进一步的阐述和说明。The present invention will be further elaborated and illustrated below in conjunction with the embodiments of the present invention.
实施例1：Example 1:
一种Φ780×35mm规格D6AE钢管的“轧制+推制”生产方法，根据设备情况，设计采用两次推制成型，即Φ508×44mm→Φ610×40mm→Φ780×35mm。A "rolling + pushing" production method of Φ780×35mm D6AE steel pipe. According to the equipment situation, the design adopts two times of pushing forming, that is, Φ508×44mm→Φ610×40mm→Φ780×35mm.
A，周期轧管机组轧管A. Periodic pipe rolling mill
首先取Φ500mm的D6AE电渣钢锭进行钢锭镗孔(Φ120mm)，然后再穿孔轧制，接着完全退火处理后矫直，得到Φ508×44mm规格的初品无缝钢管；Firstly, the D6AE electroslag steel ingot of Φ500mm is taken for ingot boring (Φ120mm), then piercing and rolling, and then straightened after complete annealing treatment, to obtain the primary seamless steel pipe with the specification of Φ508×44mm;
B，推制扩管B, pushing and expanding pipe
将步骤A得到的初品无缝钢管的管端进行平头处理、内表面喷砂除氧化皮和表面缺陷处理，然后将处理后的初品无缝钢管进行第一次推制扩管；第一次推制过程相对稳定，推制的速度较慢，为40mm/min；推制力达12MPa；由于钢管壁较厚，推制温度为740～760℃。第一次推制扩管的时间约2.5小时。The pipe end of the primary product seamless steel pipe obtained in step A is subjected to flat end treatment, the inner surface is sandblasted to remove scale and surface defects, and then the processed primary product seamless steel pipe is subjected to the first push expansion; the first The pushing process is relatively stable, the pushing speed is slow, 40mm/min; the pushing force reaches 12MPa; the pushing temperature is 740-760°C due to the thick wall of the steel pipe. The time for the first push and expansion is about 2.5 hours.
接着，对第一次推制扩管后的初品无缝钢管进行退火处理以降低钢管强度，进行第二次推制扩管，得到Φ780×35mm规格的大口径无缝钢管4；第二次推制过程开始时相对稳定，速度较慢，为20mm/min，推制力高达15MPa；推制温度为750℃左右。因为推制速度慢，第二次推制时间约8个小时。Next, anneal the primary seamless steel pipe after the first pushing and expanding to reduce the strength of the steel pipe, and carry out the second pushing and expanding to obtain a large-diameter seamless steel pipe 4 with a specification of Φ780×35mm; the second time The pushing process is relatively stable at the beginning, with a slow speed of 20mm/min and a pushing force of up to 15MPa; the pushing temperature is about 750°C. Because the pushing speed is slow, the second pushing time is about 8 hours.
C，热处理C, heat treatment
将步骤B得到的大口径无缝钢管4悬挂在井式热处理炉内进行热处理，热处理方式是阶梯式退火工艺。The large-diameter seamless steel pipe 4 obtained in step B is suspended in a well-type heat treatment furnace for heat treatment, and the heat treatment method is a stepped annealing process.
Φ780×35mm规格的大口径无缝钢管4的悬挂方式如下：The suspension method of large-diameter seamless steel pipe 4 with a specification of Φ780×35mm is as follows:
首先，如图1所示，将大口径无缝钢管4一端焊接夹持件1，所述夹持件1有四个，其间隔均匀的分布在无缝钢管的一端；所述夹持件1上焊接一圆形挂板2，所述挂板2上设置四个挂钩3，所述四个挂钩3分别位于四个夹持件1正上方；First, as shown in Figure 1, one end of the large-diameter seamless steel pipe 4 is welded with a clamping piece 1, and there are four clamping pieces 1, which are evenly spaced at one end of the seamless steel pipe; the clamping piece 1 A circular hanging plate 2 is welded on the top, and four hooks 3 are arranged on the hanging plate 2, and the four hooks 3 are respectively located directly above the four clamping parts 1;
然后，利用挂板2上的挂钩3连接牵引设备，将大口径无缝钢管4垂直悬空放入井式加热炉内；Then, utilize the hook 3 on the hanging plate 2 to connect the traction equipment, and vertically suspend the large-diameter seamless steel pipe 4 into the well-type heating furnace;
由于本实施例1制备的大口径超高强度钢无缝钢管其D/S为22.3，其长时间高温退火，钢管易发生变形，目前矫直机难以校正，因此，需要在井上热处理炉内将钢管悬挂进行热处理工艺，并且采用焊接夹持件和挂板将钢管悬空在炉内处理不会发生变椭或局部出现凹面。Since the D/S of the large-diameter ultra-high-strength steel seamless steel pipe prepared in Example 1 is 22.3, and it is annealed at high temperature for a long time, the steel pipe is prone to deformation, and it is difficult to correct the straightening machine at present. The steel pipe is suspended for heat treatment process, and the steel pipe is suspended in the furnace by welding clamps and hanging plates, and the treatment will not cause ellipse or local concave surface.
利用该方法进行大口径无缝钢管热处理，其大口径无缝钢管热处理先后的外径与内径相差不大于1mm。When the method is used for heat treatment of the large-diameter seamless steel pipe, the difference between the outer diameter and the inner diameter of the large-diameter seamless steel pipe before and after heat treatment is not more than 1mm.
接着，调整井式加热炉的温度，使温度升高至860℃后，保温20min；接着，利用井式加热炉的控温系统使大口径无缝钢管4按30℃阶梯式随炉降温，每降低一个温度需保温20min；当降低至650℃，保温90min；接着继续按30℃阶梯式至590℃，每降低一个温度需要20min；接着降低至550℃，保温30min，关闭控温系统，使大口径无缝钢管4在井式加热炉内空冷30min；具体的阶梯式退火工艺曲线图如图3所示，具体如下：Then, adjust the temperature of the well-type heating furnace to raise the temperature to 860°C, and then keep it warm for 20 minutes; then, use the temperature control system of the well-type heating furnace to make the large-diameter seamless steel pipe 4 cool down with the furnace in a stepwise manner at 30°C, each time Lower a temperature and keep it warm for 20 minutes; when it is lowered to 650°C, keep it warm for 90 minutes; then continue to step up from 30°C to 590°C, and it takes 20 minutes for each lower temperature; Caliber seamless steel pipe 4 was air-cooled in a well-type heating furnace for 30 minutes; the specific step annealing process curve is shown in Figure 3, and the details are as follows:
6小时加热至860℃→860℃保温20min→830℃保温20min→800℃保温20min→770℃保温20min→740℃保温20min→710℃保温20min→680℃保温20min→650℃保温1h30min→620℃保温20min→590℃保温20min→550℃保温30min，然后吊着空冷30min后放台架冷却。6 hours heating to 860°C→860°C for 20min→830°C for 20min→800°C for 20min→770°C for 20min→740°C for 20min→710°C for 20min→680°C for 20min→650°C for 1h30min→620°C 20min→590°C heat preservation for 20min→550°C heat preservation for 30min, then hang it in the air for 30min and put it on the bench to cool.
相比于常规退火工艺，如图2所示，具体是860℃保温0.25小时/吨，以每小时≤50℃的温降，降至650℃保温0.35小时/吨，之后再以每小时≤50℃的温降，降至550℃后出热处理炉，空冷。本实施例阶梯式退火工艺与常规退火工艺比较，在860℃和650℃分别进行的保温未做调整。但是新设计阶梯状降温分布，在热处理过程中通过阶段保温的方式，减少了温差的影响。Compared with the conventional annealing process, as shown in Figure 2, specifically, the heat preservation is 0.25 hours/ton at 860°C, the temperature drop is ≤50°C per hour, and the heat preservation is 0.35 hours/ton at 650°C, and then the temperature is ≤50°C per hour. ℃ temperature drop, down to 550 ℃, out of the heat treatment furnace, air cooling. Compared with the conventional annealing process of the step annealing process in this embodiment, the heat preservation at 860° C. and 650° C. is not adjusted. However, the newly designed step-like cooling distribution reduces the influence of temperature difference by means of step-by-step heat preservation during the heat treatment process.
本发明与原热处理工艺比较，在860℃和650℃分别进行的保温未做调整。而新设计的热处理工艺曲线如阶梯状分布，在热处理过程中通过阶段保温的方式，减少了温差的影响。Compared with the original heat treatment process in the present invention, the heat preservation at 860° C. and 650° C. is not adjusted. The newly designed heat treatment process curve is distributed in a ladder shape, and the influence of temperature difference is reduced by means of stage insulation during the heat treatment process.
经测量，采用常规退火工艺处理的无缝钢管每米弯曲度≤3mm；而采用本实施例的阶梯式退火工艺处理的无缝钢管，每米弯曲度最大为2.5mm。因此本实施例实现了无缝钢管弯曲度小，不矫直即满足技术协议要求，且性能指标完全满足技术协议要求。According to measurements, the bending degree per meter of the seamless steel pipe treated with the conventional annealing process is ≤3mm; while the bending degree per meter of the seamless steel pipe treated with the stepped annealing process of this embodiment is at most 2.5 mm. Therefore, this embodiment realizes that the seamless steel pipe has a small curvature, meets the requirements of the technical agreement without straightening, and the performance index fully meets the requirements of the technical agreement.
然后取样、检验，得到所述的大口径超高强度钢无缝钢管。Then sampling and inspection are carried out to obtain the large-diameter ultra-high-strength steel seamless pipe.
通过对无缝钢管进行硬度测定。可以得出，采用常规退火工艺处理的无缝钢管头端布氏硬度直径HBD为4.1mm，尾端为4.3mm；而采用本实施例的阶梯式退火工艺处理的无缝钢管头尾两端HBD均为4.25mm。由此可见，进过阶梯式退火工艺处理的无缝钢管的性能均匀稳定。Through hardness determination of seamless steel pipe. It can be concluded that the Brinell hardness diameter HBD at the head end of the seamless steel pipe treated by the conventional annealing process is 4.1mm, and the tail end is 4.3mm; while the HBD at both ends of the seamless steel pipe treated by the stepped annealing process of this embodiment is Both are 4.25mm. It can be seen that the performance of the seamless steel pipe treated by the step annealing process is uniform and stable.
本发明的梯度退火工艺，可有效控制温降速率，确保了钢管在退火时整管无明显温差。从而避免了钢管因温差产生的应力出现弯曲的情况，同时保证了整管性能的稳定性。The gradient annealing process of the present invention can effectively control the rate of temperature drop, ensuring that there is no obvious temperature difference throughout the steel pipe during annealing. In this way, the bending of the steel pipe due to the stress generated by the temperature difference is avoided, and at the same time, the stability of the performance of the whole pipe is ensured.
本实施例得到的Φ780×35mm规格D6AE超高强度钢无缝钢管减少了弯曲程度，不矫直即满足技术协议要求，且性能指标完全满足技术协议要求。The Φ780×35mm D6AE ultra-high-strength steel seamless steel pipe obtained in this example has reduced bending degree, meets the requirements of the technical agreement without straightening, and the performance index fully meets the requirements of the technical agreement.
尽管这里参照本发明的解释性实施例对本发明进行了描述，上述实施例仅为本发明较佳的实施方式，本发明的实施方式并不受上述实施例的限制，应该理解，本领域技术人员可以设计出很多其他的修改和实施方式，这些修改和实施方式将落在本申请公开的原则范围和精神之内。Although the present invention has been described here with reference to the illustrative examples of the present invention, the above-mentioned examples are only preferred implementations of the present invention, and the implementation of the present invention is not limited by the above-mentioned examples. It should be understood that those skilled in the art Many other modifications and implementations can be devised which will fall within the scope and spirit of the principles disclosed in this application.
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| CN102382962A (en) * | 2011-11-10 | 2012-03-21 | 浙江健力股份有限公司 | Quick spheroidizing annealing technology for GCr15 bearing steel pipe |
| CN103521548A (en) * | 2013-10-25 | 2014-01-22 | 安吉县鹏大钢管有限公司 | Method for manufacturing martensitic steel tube |
| CN103543154A (en) * | 2013-11-04 | 2014-01-29 | 攀钢集团成都钢钒有限公司 | Method for judging defect formation process of cold-drawn steel pipe |
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2014
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| CN101259582A (en) * | 2008-04-28 | 2008-09-10 | 江阴市界达特异制管有限公司 | Preparation of seamless special-shaped steel pipe for low temperature resistance oil derrick electric transmission pole tower |
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| CN102069104A (en) * | 2010-11-30 | 2011-05-25 | 攀钢集团钢铁钒钛股份有限公司 | Method for producing seamless steel tube for big-caliber long tube air bottle in hot rolling mode |
| CN102382962A (en) * | 2011-11-10 | 2012-03-21 | 浙江健力股份有限公司 | Quick spheroidizing annealing technology for GCr15 bearing steel pipe |
| CN103521548A (en) * | 2013-10-25 | 2014-01-22 | 安吉县鹏大钢管有限公司 | Method for manufacturing martensitic steel tube |
| CN103543154A (en) * | 2013-11-04 | 2014-01-29 | 攀钢集团成都钢钒有限公司 | Method for judging defect formation process of cold-drawn steel pipe |
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