CN102921749B - Method for removing surface scale of chromium-containing seamless steel tube - Google Patents
Method for removing surface scale of chromium-containing seamless steel tube Download PDFInfo
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- CN102921749B CN102921749B CN201210504397.9A CN201210504397A CN102921749B CN 102921749 B CN102921749 B CN 102921749B CN 201210504397 A CN201210504397 A CN 201210504397A CN 102921749 B CN102921749 B CN 102921749B
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Abstract
The invention provides a method for removing surface scale of a chromium-containing seamless steel tube. The method comprises the following steps of: quenching the chromium-containing seamless steel tube, and controlling remaining oxygen of a heating furnace to be less than 3 percent in the process of heating the chromium-containing seamless steel tube in the quenching step; tempering the quenched chromium-containing seamless steel tube; performing primary cooling on the tempered chromium-containing seamless steel tube so as to cool the chromium-containing seamless steel tube to the temperature of 300 DEG C or below, so that the scale cinder on the outer surface of the chromium-containing seamless steel tube is loosened; performing primary straightening on the chromium-containing seamless steel tube subjected to primary cooling by utilizing a six-roller straightening machine, so that the surface of the chromium-containing seamless steel tube is only rotated and flattened and is not bent; and finally, performing secondary cooling and secondary straightening on the chromium-containing seamless steel tube subjected to primary straightening, so that the flexibility and ovality of the chromium-containing seamless steel tube meet the requirements of a finished steel tube. According to the method, the problem that the surface scale is difficultly removed after the chromium-containing seamless steel tube is treated can be solved, so that the surface quality of the steel tube is greatly improved.
Description
Technical field
The invention belongs to field of metallurgy, specifically, the present invention relates to a kind of method removed containing chromium seamless steel pipe surface scale.
Background technology
Generally at continuous heat production line, Tempering and Quenching is carried out to large batch of seamless steel pipe.Quenching-and-tempering process comprises quenching, tempering, cooling, aligning, and continuous heat apparatus for production line is glowing furnace, high pressure water descaling device, granulating unit, tempering furnace, cold bed, straightener mainly.Seamless steel pipe is heated in glowing furnace, heating-up temperature, generally more than 850 DEG C, therefore can produce oxide skin on the surface of seamless steel pipe, makes seamless steel pipe water inlet quenching device hardening, with laggard tempering furnace tempering after coming out of the stove, to go out after tempering furnace at cold bed cooling pipe, then enter straightener aligning.
Usually, high pressure water descaling device is used the oxide skin on seamless steel pipe surface to be removed.What descaling device was generally arranged on glowing furnace or tempering furnace goes out furnace door place, series of spray nozzles water spray formation high-pressure water-ring of ring-type is arranged in descaling device, when seamless steel pipe is by water ring, water under high pressure is beaten and on the outer surface of steel pipe, is made oxide skin chilling and come off, because of the time shorter (1 ~ 3 second) of water under high pressure contact steel tube surface, the temperature drop of steel pipe body only has 20 DEG C ~ about 40 DEG C, better for common steel tube descaling device scale removal effect.
But, containing the chrome content of chromium seamless steel pipe generally between 0.8wt% ~ 5wt%, because the outer surface oxide skin making this steel pipe produce in heat treatment heating process containing chromium combines firmly, adopt common high-pressure water descaling to be difficult to outer surface oxide skin to be removed totally, thus the surface quality containing chromium seamless steel pipe can be had a strong impact on.Therefore, needing to go special sand-blast shop sandblasting could scale removal by rolling off the production line to turn from continuous heat production line containing chromium seamless steel pipe, which adds production cost, extending the production cycle.
Summary of the invention
In the prior art, for the de-scaling containing chromium seamless steel pipe, need to roll off the production line process, thus add production cost, extend the production cycle.For this reason, the invention provides a kind of to containing the method removing steel tube surface oxide skin after chromium seamless steel pipe Tempering and Quenching, the method can solve the problem that chrome-bearing steel seamless steel pipe heat treatment rear surface oxide skin is not easily removed, and significantly can improve steel tube surface quality.
The object of the present invention is to provide a kind of method removed containing chromium seamless steel pipe surface scale, described method comprises the steps: to quench to containing chromium seamless steel pipe, in quenching Step, heating is containing controlling the remaining oxygen of heating furnace during chromium seamless steel pipe below 3%; Tempering is carried out to the chromium seamless steel pipe that contains after quenching; To once cooling containing chromium seamless steel pipe after tempering, so that less than 300 DEG C will be cooled to containing chromium seamless steel pipe, the oxide skin containing chromium seamless steel pipe outer surface will be made to become loose; Utilize six-roller straightener once to align containing chromium seamless steel pipe once cooled, make only to be rotated containing chromium seamless steel pipe surface and flatten and do not have bending, to remove the oxide skin containing chromium seamless steel pipe surface; Finally, to carrying out cooling twice and secondary aligning containing chromium seamless steel pipe after once aligning, the requirement reaching fished pipe containing the flexibility of chromium seamless steel pipe and ovality is made.
According to the present invention, in a straightening step, by the center of three of six-roller straightener upper straightening rolls adjustment in one in the heart, and by the adjustment of the center of three of six-roller straightener lower smoothing rolls in one in the heart, make containing chromium seamless steel pipe is only slightly flattened by three pairs of smoothing rolls after entering six-roller straightener not bending.
According to the present invention, in cooling twice step, can will be cooled to normal temperature containing chromium seamless steel pipe after once aligning.
According to the present invention, in secondary straightening step, two pairs of smoothing roll height that six-roller straightener can be adjusted to a pair middle smoothing roll and front and back are inconsistent, make to be bent by a pair smoothing roll of centre after entering six-roller straightener containing chromium seamless steel pipe, and flattened by three pairs of smoothing rolls.
Therefore, according to the present invention, the method of steel tube surface oxide skin is removed after providing a kind of chrome-bearing steel seamless steel pipe Tempering and Quenching, the method can solve the problem that chrome-bearing steel seamless steel pipe heat treatment rear surface oxide skin is not easily removed, significantly improve steel tube surface quality, rub oxide skin with the hands by straightener, do not need to use high pressure water descaling device.The present invention is that the production of chrome-bearing steel seamless steel pipe provides a kind of selection newly, has broad application prospects.
Accompanying drawing explanation
Fig. 1 shows according to the flow chart of removal of the present invention containing the method for chromium seamless steel pipe surface scale.
Fig. 2 shows the structural representation of the six-roller straightener used in a straightening step in the method for removal according to the present invention containing chromium seamless steel pipe surface scale.
Detailed description of the invention
The invention provides a kind of method being removed the oxide skin containing chromium seamless steel pipe surface on continuous heat production line by improving technique, to avoid making steel pipe roll off the production line, thus improve process efficiency, shorten the process time.
The method of the oxide skin according to removal chrome-bearing steel seamless steel pipe surface of the present invention is described in detail below in conjunction with accompanying drawing.
Fig. 1 shows according to the flow chart of removal of the present invention containing the method for chromium seamless steel pipe surface scale.Fig. 2 shows the structural representation of the six-roller straightener used in a straightening step in the method for removal according to the present invention containing chromium seamless steel pipe surface scale.
As shown in Figure 1, comprise performing quenching, tempering, once cooling containing chromium seamless steel pipe according to removal of the present invention containing the method for chromium seamless steel pipe surface scale, once aligning, cooling twice, secondary align six steps.Specifically, in the step of quenching containing chromium seamless steel pipe, control the remaining oxygen of heating furnace during Quench heating in 3%(percent by volume) below, to reduce oxide skin as much as possible in the generation containing chromium seamless steel pipe surface.Once cooling refers to that the steel pipe after by tempering is cooled to less than 300 DEG C on cold bed, becomes loose to make the oxide skin containing chromium seamless steel pipe outer surface.One time straightening step adopts six-roller straightener, as shown in Figure 2, the center adjustment of three upper straightening rolls of this six-roller straightener is on a center line, the center adjustment of three lower smoothing rolls of this six-roller straightener is on a center line, thus when once bending cooled containing after chromium seamless steel pipe enters straightener, and only rotated and flatten.Cooling twice refers to steel pipe and on cold bed, be cooled to normal temperature after once aligning.Secondary aligning refers to that straightener adjusts by normal parameter, namely a pair smoothing roll in the middle of and two pairs of smoothing roll height of front and back inconsistent, bent by a pair smoothing roll of centre after steel pipe enters straightener, and flattened by three pairs of smoothing rolls, thus improve the flexibility of steel pipe and ovality to reach the requirement of fished pipe simultaneously.
According to the present invention, the oxide skin removing steel tube surface comprises the work of two aspects, and one is the generation as far as possible reducing steel pipe oxide skin when heating, and two is Ex-all oxide skin of trying one's best in steel pipe cooling procedure.Present inventor finds after deliberation, keeps the remaining oxygen of heating furnace when Quench heating steel pipe below 3%, can avoid generating blocked up oxide skin.
In addition, Ex-all oxide skin of will trying one's best in the cooling procedure of seamless steel pipe then needs the change of research oxide skin in cooling procedure.Typical seamless steel pipe scale structure is by the thinner Fe of outermost layer
2o
3the Fe in layer, intermediate layer
3o
4the FeO layer that the thickness of layer and close matrix side is the thickest forms.For chrome-bearing steel seamless steel pipe, be difficult to the mainly FeO layer removed most.According to Fe-O equilbrium phase diagram, when 570 DEG C (not containing) ~ 1371 DEG C, FeO is in stable state, and 570 DEG C (contain) below time, eutectoid reaction generation α Fe+Fe to be there is in FeO
3o
4mix products, therefore, when containing chromium seamless steel pipe be chilled on cold bed less than 300 DEG C time, FeO fully decomposes and reduces with the adhesion of steel pipe matrix, thus by adjustment six-roller straightener parameter utilize smoothing roll by oxide skin stranding fall.
Therefore, according to the method for removal of the present invention containing chromium seamless steel pipe surface scale, Quench heating, containing keeping the remaining oxygen of heating furnace during chromium seamless steel pipe below 3%, generates as few as possible to make oxide skin, steel pipe after tempering is first cooled to less than 300 DEG C on cold bed, and outer surface of steel tube FeO oxide skin becomes loose because fully decomposing, then, make once cooledly to enter six-roller straightener once align containing chromium seamless steel pipe, by this six-roller straightener being adjusted to the center adjustment of its three upper straightening rolls point-blank, and the adjustment of the center of its three lower smoothing rolls point-blank, only slightly flattened by three pairs of smoothing rolls after steel pipe enters straightener, and can not bend, therefore, when steel pipe rotary advances through three pairs of smoothing rolls, oxide skin containing chromium seamless steel pipe outer surface is rubbed with the hands by smoothing roll, thus, once aligning is main removes the oxide skin of steel tube surface and slightly improves the ovality of steel pipe.In sum, by reducing heating furnace remaining oxygen, control steel pipe and enter the temperature of straightener and steel pipe oxide skin is thoroughly removed in this triplicity of adjustment straightener parameter.In addition, according to the method for removal of the present invention containing chromium seamless steel pipe surface scale, once after aligning, steel pipe cools on cold bed, enter secondary straightener secondary aligning again, secondary straightener, by normal straightening parameters adjustment, makes the flexibility of steel pipe and ovality be improved to reach the requirement of fished pipe.
Below in conjunction with embodiment, the specific embodiment of the present invention is further described, does not therefore limit the present invention among described scope of embodiments.
embodiment: adopt method of the present invention to produce 30CrMo steel seamless steel tube
By API 5CT standard production steel grade be 30CrMo, grade of steel is L80-1, specification is the steel pipe of 114.3mm × 6.88mm.The specific chemical composition of 30CrMo seamless steel pipe is shown in table 1 below, and Cr content is 0.90wt% ~ 1.20wt%.
The chemical composition (% by weight) of table 1 seamless steel pipe
In this embodiment, the technological process of producing 30CrMo seamless steel pipe is as follows: electric furnace steel making, continuous casting 200 bases → hot rolling → quenching → tempering → once cooling → once aligning → cooling twice → secondary aligning → flaw detection, hydraulic pressure, inspection, packaging.
Quenching temperature is 920 DEG C, and during heating, heating furnace remaining oxygen remains between 2.1% ~ 2.8%.After tempering, steel pipe cools 8 minutes on cold bed, and now, the temperature of outer surface of steel tube is 270 DEG C, and the temperature of steel pipe internal-surface is 290 DEG C.Then, enter six-roller straightener aligning, smoothing roll relative reduction be set to 1(i.e. three upper straightening roll centers on a center line, three lower smoothing roll centers are on a center line), the flattening amount of often pair of smoothing roll is 0.2% of outer diameter of steel pipes, and after aligning, steel pipe surface surface oxidized skin all comes off.Then, cold bed is cooled to less than 40 DEG C, then enters six-roller straightener aligning, smoothing roll relative reduction is set to 0.63, and the flattening amount of often pair of smoothing roll is 1% of outer diameter of steel pipes, and after rectifying, flexibility of steel pipe is below 1mm/m, ovality is less than 0.75%, reaches the requirement of fished pipe.
Therefore, according to the present invention, the method of steel tube surface oxide skin is removed after providing a kind of chrome-bearing steel seamless steel pipe Tempering and Quenching, the method can solve the problem that chrome-bearing steel seamless steel pipe heat treatment rear surface oxide skin is not easily removed, significantly improve steel tube surface quality, rub oxide skin with the hands by straightener, do not need to use high pressure water descaling device.The present invention is that the production of chrome-bearing steel seamless steel pipe provides a kind of selection newly, has broad application prospects.
Although specifically illustrate with reference to exemplary embodiment of the present invention and describe the present invention, but it should be understood by one skilled in the art that, when not departing from the spirit and scope of the present invention limited by claim and equivalent thereof, the change in various forms and details can be made at this.
Claims (4)
1. remove the method containing chromium seamless steel pipe surface scale, it is characterized in that described method comprises the steps:
Quench to containing chromium seamless steel pipe, in quenching Step, heating is 2.1% ~ 2.8% containing the remaining oxygen of control heating furnace during chromium seamless steel pipe;
Tempering is carried out to the chromium seamless steel pipe that contains after quenching;
To once cooling containing chromium seamless steel pipe after tempering, so that less than 300 DEG C will be cooled to containing chromium seamless steel pipe, the oxide skin containing chromium seamless steel pipe outer surface will be made to become loose;
Utilize six-roller straightener once to align containing chromium seamless steel pipe once cooled, make only to be rotated containing chromium seamless steel pipe surface and flatten and do not have bending, to remove the oxide skin containing chromium seamless steel pipe surface;
Finally, to carrying out cooling twice and secondary aligning containing chromium seamless steel pipe after once aligning, make the requirement reaching fished pipe containing the flexibility of chromium seamless steel pipe and ovality,
Wherein, described is 30CrMo steel seamless steel tube containing chromium seamless steel pipe.
2. removal according to claim 1 is containing the method for chromium seamless steel pipe surface scale, it is characterized in that in a straightening step, by the center of three of six-roller straightener upper straightening rolls adjustment in one in the heart, and by the adjustment of the center of three of six-roller straightener lower smoothing rolls in one in the heart, make containing chromium seamless steel pipe is only slightly flattened by three pairs of smoothing rolls after entering six-roller straightener not bending.
3. removal according to claim 1 is containing the method for chromium seamless steel pipe surface scale, it is characterized in that in cooling twice step, and the chromium seamless steel pipe that contains after once aligning is cooled to normal temperature.
4. removal according to claim 1 is containing the method for chromium seamless steel pipe surface scale, it is characterized in that in secondary straightening step, two pairs of smoothing roll height that six-roller straightener is adjusted to a pair middle smoothing roll and front and back are inconsistent, make to be bent by a pair smoothing roll of centre after entering six-roller straightener containing chromium seamless steel pipe, and flattened by three pairs of smoothing rolls.
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| CN102921749B true CN102921749B (en) | 2015-03-04 |
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| CN107952910A (en) * | 2017-11-21 | 2018-04-24 | 金华市金钟焊接材料有限公司 | A kind of B alloy wire coalignment |
| CN108202084A (en) * | 2018-03-20 | 2018-06-26 | 湖州中杭轧辊有限公司 | A kind of middle-size and small-size roll of multipurpose sprays machine of quenching |
Citations (4)
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| CN1085139A (en) * | 1993-08-07 | 1994-04-13 | 机械电子工业部西安重型机械研究所 | High precision pipe straightener |
| CN1761537A (en) * | 2003-04-07 | 2006-04-19 | 材料制造有限公司 | Method of removing scale and inhibiting oxidation in processed sheet metal |
| CN1939656A (en) * | 2005-09-30 | 2007-04-04 | 宝山钢铁股份有限公司 | Production of L80-13Cr oil casings |
| CN101418421A (en) * | 2008-12-09 | 2009-04-29 | 山东墨龙石油机械股份有限公司 | High intensity oil casing tube for resisting sulfurated hydrogen corrosion and method for producing the same |
Family Cites Families (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS5576014A (en) * | 1978-12-02 | 1980-06-07 | Chugai Ro Kogyo Kaisha Ltd | Heat treating method of steel material having rolling scale and heat treating furnace thereof |
| JP3293246B2 (en) * | 1993-07-02 | 2002-06-17 | 日本鋼管株式会社 | Manufacturing method of seamless steel pipe |
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- 2012-11-30 CN CN201210504397.9A patent/CN102921749B/en active Active
Patent Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN1085139A (en) * | 1993-08-07 | 1994-04-13 | 机械电子工业部西安重型机械研究所 | High precision pipe straightener |
| CN1761537A (en) * | 2003-04-07 | 2006-04-19 | 材料制造有限公司 | Method of removing scale and inhibiting oxidation in processed sheet metal |
| CN1939656A (en) * | 2005-09-30 | 2007-04-04 | 宝山钢铁股份有限公司 | Production of L80-13Cr oil casings |
| CN101418421A (en) * | 2008-12-09 | 2009-04-29 | 山东墨龙石油机械股份有限公司 | High intensity oil casing tube for resisting sulfurated hydrogen corrosion and method for producing the same |
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