CN103114249A - Method for producing medium-wall 20G seamless steel pipe by using controlled rolling instead of normalizing - Google Patents
Method for producing medium-wall 20G seamless steel pipe by using controlled rolling instead of normalizing Download PDFInfo
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Abstract
The invention provides a method for producing a medium-wall 20G seamless steel pipe by using controlled rolling instead of normalizing. The method is used for producing the 20G seamless steel pipe with wall thickness of 16mm-40mm and is used in the fields of seamless steel pipes for high-pressure boilers, seamless steel pipes for chemical fertilizers, seamless steel pipes for alumina digestion pipelines and the like. The method has the beneficial effects that 0.03-0.07% of V is added to 20G steel and simultaneously the ranges of C, Mn, P, S and P+S in the chemical components of the 20G steel are adjusted to be 0.17-0.21%, 0.50-0.65%, not more than 0.015%, not more than 0.010% and 0.020% respectively so as to improve the yield strength and impact toughness of thick-walled hot-rolled pipes, and meanwhile, the finish rolling temperature is controlled to be 850-950 DEG C; all the performance indexes of the 20G seamless steel pipe with wall thickness of 16mm-40mm produced by adopting steel controlled hot rolling instead of normalizing heat treatment completely meet the requirements of GB5310 20G high-pressure boiler pipes; the production efficiency is improved; and the cost is reduced.
Description
Technical field
The present invention relates to a kind of method of manufacturing seamless steel pipe, particularly a kind of manufacture method that replaces heavy wall 20G weldless steel tube in normalizing production with controlled rolling.
Background technology
20G is a kind of widely used carbon steel steel grade, mainly for the production of the seamless steel tubes and pipes for high pressure boiler of all size, chemical fertilizer with weldless steel tube and alumina leaching pipeline weldless steel tube.At present, wall thickness can be used rolling controlling method production less than the weldless steel tube of 16mm, need not carry out its performance of normalizing thermal treatment and also can reach the performance index of technical requirements.Wall thickness must carry out normalizing thermal treatment to it more than or equal to the weldless steel tube of 16mm, otherwise is not the minimum value that yield strength does not reach the technical requirements regulation, is exactly that impact property is defective.Secondly, carry out normalizing thermal treatment energy consumption large, wait for that heat treatment time is long, also need to remove the oxide skin that generates because of thermal treatment after while thermal treatment, so production efficiency is low, production cost is high.
Summary of the invention
For needing normalizing thermal treatment just can make its performance reach the deficiency of standard code in heavy wall 20G seamless steel tube production technology in existing, the purpose of this invention is to provide a kind of manufacture method that replaces heavy wall 20G weldless steel tube in normalizing production with controlled rolling, can produce without normalizing treatment the 20G weldless steel tube that performance reaches standard-required to satisfy.
For achieving the above object, the technical solution used in the present invention is to provide a kind of manufacture method that replaces heavy wall 20G weldless steel tube in normalizing production with controlled rolling, adopts the performance of the middle heavy wall 20G weldless steel tube of the method production to satisfy the performance requriements that high-duty boiler is used the 20G weldless steel tube fully.
For achieving the above object, the technical solution used in the present invention is to provide a kind of manufacture method that replaces heavy wall 20G weldless steel tube in normalizing production with controlled rolling, and the method comprises the following steps:
1. batching smelting, continuous casting
Weight proportion by 20G steel steel grade element is: C:0.17 ~ 0.21%, Si:0.17～0.37%, Mn:0.50～0.65%, P≤0.015%, S≤0.010%, P+S≤0.020%, Mo≤0.15%, Cr≤0.30%, Cu≤0.25%, Ni≤0.25%, V:0.030～0.070%, all the other are iron, the impurity element trace;
Batching is by electric furnace or converter steelmaking, add Si-Ca-Ba to carry out pre-deoxidation in tapping process and process, molten steel carries out the LF refining, feeds the deoxidation of silico-calcium silk, molten steel after refining is complete is processed and adds appropriate aluminium wire through VD or RH vacuum stripping, goes up continuous casting platform subsequently and carries out the continuous casting base;
2. rolling
Scale continuously cast bloom after the assay was approved heats in rotary heating furnace, and furnace temperature of heating furnace is controlled to be 1250～1290 ℃, and piercing temperature is controlled to be 1200～1250 ℃, 850～950 ℃ of finishing temperatures, and cooling, the 20G weldless steel tube is made in sawing;
For diameter less than or equal to
The 20G weldless steel tube, adopt PQF hot continuous rolling unit rolling; For diameter greater than
The 20G weldless steel tube, hot continuous rolling+720 oblique rolling extension diameter tube rolling units are rolling to adopt PQF;
The wall thickness of above-mentioned controlled rolling is that the index of mechanical property of 20G weldless steel tube of 16～40mm is as follows:
Yield strength Rel: 〉=245MPa,
The yield strength Rel of 450 ℃: 〉=150MPa,
Tensile strength Rm:410～550MPa,
Summer is than V-type impelling strength: 20 ℃ of vertical full-scale Charpy-V impact power 〉=40J, and 20 ℃ of horizontal full-scale Charpy-V impact power 〉=27J,
Unit elongation: 〉=24%,
Grain fineness number: more than 5 grades.
Effect of the present invention is to use the advantage of the method:
(1) add trace 0.03～0.07%V in the 20G steel grade, to improve the yield strength of thick wall hot-rolled pipe, the scope with C, Mn etc. is adjusted into 0.17 ~ 0.21%C, 0.50 ~ 0.65%Mn simultaneously, P≤0.015%, S≤0.010%, P+S≤0.020% is to improve impelling strength.Adopt the wall thickness weldless steel tube property indices of this steel grade production to reach the requirement of high pressure boiler tube fully;
(2) finishing temperature at 850～950 ℃, has improved the mechanical property of steel pipe;
(3) controlled rolling is compared with conventional hot rolling+normalizing heat treatment technique, has removed the operations such as normalizing thermal treatment, scale removal, has shortened Production Flow Chart and time, has therefore improved production efficiency, has reduced manufacturing cost.
Embodiment
Replace the manufacture method of heavy wall 20G weldless steel tube in normalizing production to be illustrated of the present invention with controlled rolling in conjunction with the embodiments.
The manufacture method that replaces heavy wall 20G weldless steel tube in normalizing production with controlled rolling of the present invention, the method comprises the following steps:
1. batching smelting, continuous casting
Weight proportion by 20G steel steel grade element is: C:0.17 ~ 0.21%, Si:0.17～0.37%, Mn:0.50～0.65%, P≤0.015%, S≤0.010%, P+S≤0.020%, Mo≤0.15%, Cr≤0.30%, Cu≤0.25%, Ni≤0.25%, V:0.030～0.070%, all the other are iron, the impurity element trace;
Batching is by electric furnace or converter steelmaking, add Si-Ca-Ba to carry out pre-deoxidation in tapping process and process, molten steel carries out the LF refining, feeds the deoxidation of silico-calcium silk, molten steel after refining is complete is processed and adds appropriate aluminium wire through VD or RH vacuum stripping, goes up continuous casting platform subsequently and carries out continuous casting;
2. rolling
Scale continuously cast bloom after the assay was approved heats in rotary heating furnace, and furnace temperature of heating furnace is controlled to be 1250～1290 ℃, and piercing temperature is controlled to be 1200～1250 ℃, and 850～950 ℃ of finishing temperatures are cooling, sawing;
For diameter less than or equal to
The 20G steel pipe, adopt PQF hot continuous rolling unit rolling; For diameter greater than
The 20G steel pipe, hot continuous rolling+720 oblique rolling extension diameter tube rolling units are rolling to adopt PQF;
The wall thickness of above-mentioned controlled rolling is that the index of mechanical property of 20G weldless steel tube of 16～40mm is as follows:
Yield strength Rel: 〉=245MPa,
The yield strength Rel of 450 ℃: 〉=150MPa,
Tensile strength Rm:410～550MPa,
Summer is than V-type impelling strength: 20 ℃ of vertical full-scale Charpy-V impact power 〉=40J, and 20 ℃ of horizontal full-scale Charpy-V impact power 〉=27J,
Unit elongation: 〉=24%,
Grain fineness number: more than 5 grades.
Of the present invention with the 20G steel in the manufacture method of heavy wall 20G weldless steel tube in controlled rolling replacement normalizing production, the weight proportion of steel grade component is C:0.17 ~ 0.21%, Si:0.17～0.37%, Mn:0.50～0.65%, P≤0.015%, S≤0.010%, P+S≤0.020%, Mo≤0.15%, Cr≤0.30%, Cu≤0.25%, Ni≤0.25%, V:0.030～0.070%, all the other are iron, the impurity element trace.
The chief component composition is chosen be the reasons are as follows:
Carbon: be main strengthening element, have advantages of that cost is low, regulation and control susceptibility is good.Carbon content height is proportional with the intensity of steel, but the impelling strength of steel obviously reduces, and considers the factor of each side, and carbon content control is between 0.16～0.22%, and optimum range is 0.17～0.21%.
Manganese: in steel take solution strengthening effect as main.Studies show that, what and intensity of manganese content is proportional in steel, and its impact toughness decreased rate is less, does not also affect its brittle transition temperature.For improving controlled rolling 20G toughness, the design's 20G is best, and manganese content is 0.55～0.65%.
Vanadium: vanadium is the trace element of the main interpolation of this steel.Vanadium V (the C that strain inducing is separated out in the operation of rolling, N) can stop the austenitic recrystallize of deformation, and can stop the alligatoring of recrystallize austenite crystal, but this effect weakens with the reduction of nitrogen in steel content, and the vanadium micro-alloyed steel of common nitrogen content can produce comparatively significantly precipitation strength effect 800 ℃ of following temperature.The most important effect of vanadium is a large amount of Precipitations and produce strong precipitation strength effect in ferrite, even this effect is also fairly obvious in hot-strip.The content that designs V for this this steel grade is 0.03～0.07%, and the best is 0.04～0.06%.
Chrome molybdenum: in carbon steel, the chrome molybdenum of trace generally is solid-solubilized in ferrite, increases the matrix strength of steel, hinders dislocation motion, improves creep rupture strength, but content too much has the bainite of formation risk, thus Cr, Mo content be controlled at respectively≤0.15%.
Copper nickel: nickel reduces ferrite fault energy, improves low-temperature flexibility, and content is harmful to enduring quality again greater than 0.5%, thus the content of nickel be controlled at≤0.30%.Copper can improve intensity and the erosion resistance of steel, but the hot-short phenomenon that the segregation of copper will cause, for this reason its residual volume be controlled to be≤0.25%.
Aluminium: in steel, residual aluminum is mainly derived from deoxidation products, and unnecessary aluminium is combined with nitrogen, crystal grain thinning.Yet the Al element impels the carbon steel greying, and the enduring quality of greying infringement steel.Therefore, in the design's 20G steel Al content be controlled to be≤0.025%.
Sulphur phosphorus: the toughness of sulphur, phosphorus infringement steel, lower sulphur phosphorus content is controlled the low-temperature flexibility that has guaranteed steel.Therefore, P content is controlled at≤0.015%, and S content is controlled at≤0.010, and best S content is controlled at≤and 0.005%, P+S≤0.020%.
The manufacture method that replaces heavy wall 20G weldless steel tube in normalizing production with controlled rolling of the present invention, its step includes:
1. batching smelting, continuous casting
By above-mentioned steel grade component weight item be: C:0.17 ~ 0.21%, Si:0.17～0.37%, Mn:0.50～0.65%, P≤0.015%, S≤0.010%, P+S≤0.020%, Mo≤0.15%, Cr≤0.30%, Cu≤0.25%, Ni≤0.25%, V:0.030～0.070%, all the other are iron, the impurity element trace.Specifically as shown in table 1.
Table 1 chemical component table (wt%)
Batching is by electric furnace or converter steelmaking, add Si-Ca-Ba to carry out pre-deoxidation in tapping process and process, molten steel carries out the LF refining, feeds the deoxidation of silico-calcium silk, molten steel after refining is complete is processed and adds appropriate aluminium wire through VD or RH vacuum stripping, goes up continuous casting platform subsequently and carries out continuous casting.
2. rolling
Scale continuously cast bloom after the assay was approved heats in rotary heating furnace, and furnace temperature of heating furnace is controlled to be 1250～1290 ℃, and piercing temperature is controlled to be 1200～1250 ℃, and 850～950 ℃ of finishing temperatures are cooling, sawing.
For diameter less than or equal to
The 20G steel pipe, adopt PQF hot continuous rolling unit rolling; For diameter greater than
The 20G steel pipe, hot continuous rolling+720 oblique rolling extension diameter tube rolling units are rolling to adopt PQF.
The wall thickness of above-mentioned controlled rolling is that the index of mechanical property of 20G weldless steel tube of 16～40mm is as follows:
Yield strength Rel: 〉=245MPa,
The yield strength Rel of 450 ℃: 〉=150MPa,
Tensile strength Rm:410～550MPa,
Summer is than V-type impelling strength: 20 ℃ of vertical full-scale Charpy-V impact power 〉=40J, and 20 ℃ of horizontal full-scale Charpy-V impact power 〉=27J,
Unit elongation: 〉=24%,
Grain fineness number: more than 5 grades.
Embodiment 1 Φ 377*25mm20G weldless steel tube
1, batching smelting, continuous casting
By above-mentioned steel grade component weight item be: C:0.18%, Si:0.25%, Mn:0.55%, P≤0.015%, S≤0.005%, P+S≤0.020%, Mo≤0.15%, Cr≤0.30%, Cu≤0.25%, Ni≤0.25%, V:0.05%, all the other are iron, the impurity element trace.The working control alloying constituent is as shown in table 2 below.
Batching is by electric furnace or converter steelmaking, add Si-Ca-Ba to carry out pre-deoxidation in tapping process and process, molten steel carries out the LF refining, feeds the deoxidation of silico-calcium silk, molten steel after refining is complete is processed and adds appropriate aluminium wire through VD or RH vacuum stripping, goes up continuous casting platform subsequently and carries out continuous casting.Continuous cast round billets diameter of phi 310mm.
Table 2 chemical composition
2. rolling
Scale continuously cast bloom after the assay was approved heats in rotary heating furnace, and furnace temperature of heating furnace is controlled to be 1260 ℃, and piercing temperature is controlled to be 1230 ℃, 850 ℃ of finishing temperatures, and then cold bed is cooling, sawing.The product performance test result is as shown in table 3 below.Wherein the metallographic structure of sequence number 1 is F+P, and grain fineness number is 7.5 grades; The metallographic structure of sequence number 2 is F+P.Grain fineness number is 7.0 grades.20 ℃ of full-scale Charpy-V impact powers are greater than 27J.
Table 3 Φ 377*25mm end properties
Example 2 Φ 325*32mm20G weldless steel tubes
1, batching smelting, continuous casting
By above-mentioned steel grade component weight item be: C:0.19%, Si:0.25%, Mn:0.58%, P≤0.010%, S≤0.010%, P+S≤0.020%, Mo≤0.15%, Cr≤0.30%, Cu≤0.25%, Ni≤0.25%, V:0.06%, all the other are iron, the impurity element trace.The working control alloying constituent is as shown in table 4 below.
Batching is by electric furnace or converter steelmaking, add Si-Ca-Ba to carry out pre-deoxidation in tapping process and process, molten steel carries out the LF refining, feeds the deoxidation of silico-calcium silk, molten steel after refining is complete is processed and adds appropriate aluminium wire through VD or RH vacuum stripping, goes up continuous casting platform subsequently and carries out continuous casting.Continuous cast round billets diameter of phi 310mm.
Table 4 chemical composition
2. rolling
Scale continuously cast bloom after the assay was approved heats in rotary heating furnace, and furnace temperature of heating furnace is controlled to be 1230 ℃, and piercing temperature is controlled to be 1200 ℃, 950 ℃ of finishing temperatures, and then cold bed is cooling, sawing.
The product performance test result is as shown in table 5 below.Metallographic structure is F+P, and grain fineness number is 7.0 grades, and 20 ℃ of full-scale Charpy-V impact powers are greater than 27J.
Table 5 Φ 325*32mm end properties
Example 3 Φ 273*40mm20G weldless steel tubes
1, batching smelting, continuous casting
By above-mentioned steel grade component weight item be: C:0.18%, Si:0.25%, Mn:0.56%, P≤0.015%, S≤0.005%, P+S≤0.020%, Mo≤0.15%, Cr≤0.30%, Cu≤0.25%, Ni≤0.25%, V:0.04%, all the other are iron, the impurity element trace.The working control alloying constituent is as shown in table 6 below.
Batching is by electric furnace or converter steelmaking, add Si-Ca-Ba to carry out pre-deoxidation in tapping process and process, molten steel carries out the LF refining, feeds the deoxidation of silico-calcium silk, molten steel after refining is complete is processed and adds appropriate aluminium wire through VD or RH vacuum stripping, goes up continuous casting platform subsequently and carries out continuous casting.Continuous cast round billets diameter of phi 310mm.
Table 6 chemical composition
2. rolling
Scale continuously cast bloom after the assay was approved heats in rotary heating furnace, and furnace temperature of heating furnace is controlled to be 1230 ℃, and piercing temperature is controlled to be 1180 ℃, 950 ℃ of finishing temperatures, and then cold bed is cooling, sawing.
The product performance test result is as shown in table 7 below.Metallographic structure is F+P, and grain fineness number is 7.0 grades, and 20 ℃ of full-scale Charpy-V impact powers are greater than 27J.
Table 7 Φ 274*40mm end properties
Middle thick-walled seamless steel pipes performance of the present invention satisfies the requirement of 20G weldless steel tube fully, and interior China and foreign countries hardness is even, and homogeneous microstructure is ferrite+pearlitic structure.
According to embodiments of the invention, can estimate that production operation of the present invention easily carries out, without normalizing thermal treatment, shortened Production Flow Chart and time, therefore improved production efficiency.Secondly, originally said with respect to the one-tenth of the trace vanadium that adds, the total manufacturing cost of steel pipe still has substantial degradation, and has good popularizing application prospect.
Claims (1)
- One kind with controlled rolling replace normalizing produce in the manufacture method of heavy wall 20G weldless steel tube, the method comprises the following steps:1. batching smelting, continuous castingThe weight proportion of the element of steel is: C:0.17 ~ 0.21%, Si:0.17～0.37%, Mn:0.50～0.65%, P≤0.015%, S≤0.010%, P+S≤0.020%, Mo≤0.15%, Cr≤0.30%, Cu≤0.25%, Ni≤0.25%, V:0.030～0.070%, all the other are iron, the impurity element trace;Batching is by electric furnace or converter steelmaking, add Si-Ca-Ba to carry out pre-deoxidation in tapping process and process, molten steel carries out the LF refining, feeds the deoxidation of silico-calcium silk, molten steel after refining is complete is processed and adds appropriate aluminium wire through VD or RH vacuum stripping, goes up continuous casting platform subsequently and carries out the continuous casting base;2. rollingScale continuously cast bloom after the assay was approved heats in rotary heating furnace, and furnace temperature of heating furnace is controlled to be 1250～1290 ℃, and piercing temperature is controlled to be 1200～1250 ℃, 850～950 ℃ of finishing temperatures, and cooling, the 20G weldless steel tube is made in sawing;For diameter less than or equal to The 20G weldless steel tube, adopt PQF hot continuous rolling unit rolling; For diameter greater thanThe 20G weldless steel tube, hot continuous rolling+720 oblique rolling extension diameter tube rolling units are rolling to adopt PQF;
The wall thickness of above-mentioned controlled rolling is that the index of mechanical property of 20G weldless steel tube of 16～40mm is as follows:Yield strength Rel: 〉=245MPa,The yield strength Rel of 450 ℃: 〉=150MPa,Tensile strength Rm:410～550MPa,Summer is than V-type impelling strength: 20 ℃ of vertical full-scale Charpy-V impact power 〉=40J, and 20 ℃ of horizontal full-scale Charpy-V impact power 〉=27J,Unit elongation: 〉=24%,Grain fineness number: more than 5 grades.
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Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN104357752A (en) * | 2014-10-21 | 2015-02-18 | 盐城奥克阀门有限公司 | Alloy material for valve casting and processing process thereof |
| CN104593543A (en) * | 2015-01-07 | 2015-05-06 | 宁波万冠精密铸造厂 | Steelmaking method |
| CN113862568A (en) * | 2021-09-23 | 2021-12-31 | 天津钢管制造有限公司 | Seamless steel pipe for water drainage in coal mine exploration and manufacturing method |
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| CN101892443A (en) * | 2010-07-09 | 2010-11-24 | 天津钢管集团股份有限公司 | High strength and high toughness petroleum casing pipe at steel grade with yield strength of 170-180ksi and manufacturing method thereof |
| CN102181800A (en) * | 2011-04-13 | 2011-09-14 | 安徽天大石油管材股份有限公司 | Fire-resistant seamless steel pipe for building and machining method thereof |
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- 2013-02-25 CN CN201310058015.9A patent/CN103114249B/en active Active
Patent Citations (2)
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| CN101892443A (en) * | 2010-07-09 | 2010-11-24 | 天津钢管集团股份有限公司 | High strength and high toughness petroleum casing pipe at steel grade with yield strength of 170-180ksi and manufacturing method thereof |
| CN102181800A (en) * | 2011-04-13 | 2011-09-14 | 安徽天大石油管材股份有限公司 | Fire-resistant seamless steel pipe for building and machining method thereof |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN104357752A (en) * | 2014-10-21 | 2015-02-18 | 盐城奥克阀门有限公司 | Alloy material for valve casting and processing process thereof |
| CN104357752B (en) * | 2014-10-21 | 2016-11-23 | 盐城奥克阀门有限公司 | A kind of alloy material for valve casting and process technique thereof |
| CN104593543A (en) * | 2015-01-07 | 2015-05-06 | 宁波万冠精密铸造厂 | Steelmaking method |
| CN113862568A (en) * | 2021-09-23 | 2021-12-31 | 天津钢管制造有限公司 | Seamless steel pipe for water drainage in coal mine exploration and manufacturing method |
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Effective date of registration: 20190624 Address after: No. 396 Jintang Highway, Dongli District, Tianjin 300301 Patentee after: Tianjin Steel Tube Manufacturing Co., Ltd. Address before: No. 396 Jintang Highway, Dongli District, Tianjin 300301 Patentee before: Tianjin Steel Pipe Group Co., Ltd. |