CN103114249B - 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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- CN103114249B CN103114249B CN201310058015.9A CN201310058015A CN103114249B CN 103114249 B CN103114249 B CN 103114249B CN 201310058015 A CN201310058015 A CN 201310058015A CN 103114249 B CN103114249 B CN 103114249B
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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, weldless steel tube and alumina leaching pipeline weldless steel tube for chemical fertilizer.At present, wall thickness is less than the weldless steel tube of 16mm can be produced with rolling controlling method, need not carry out its performance of normalizing thermal treatment and also can reach the performance index of technical requirements.The weldless steel tube that wall thickness is more than or equal to 16mm must carry out normalizing thermal treatment to it, otherwise is not that yield strength does not reach the minimum value that technical requirements specifies, is exactly that impact property is defective.Secondly, carry out normalizing thermal treatment energy consumption large, wait for that heat treatment time is long, after while thermal treatment, also need to remove the oxide skin generating because of thermal treatment, therefore production efficiency is low, and production cost is high.
Summary of the invention
For needing normalizing thermal treatment just can make its performance reach the deficiency that standard specifies in existing middle heavy wall 20G seamless steel tube production technology, the object of this invention is to provide a kind of with controlled rolling replace normalizing produce in the manufacture method of heavy wall 20G weldless steel tube, to meet the 20G weldless steel tube that can produce performance and reach standard-required without normalizing treatment.
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 meet the performance requriements of high-duty boiler 20G weldless steel tube completely.
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
By the weight proportion of 20G steel steel grade element 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, impurity element trace;
After batching through electric furnace or converter steelmaking, in tapping process, add Si-Ca-Ba to carry out pre-deoxidation processing, molten steel carries out 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 base;
2. rolling
Scale continuously cast bloom after the assay was approved heats in rotary heating furnace, and heating-furnace temperature control is 1250～1290 DEG C, and piercing temperature control is 1200～1250 DEG C, 850～950 DEG C of finishing temperatures, and cooling, 20G weldless steel tube is made in sawing;
Be less than or equal to for diameter
20G weldless steel tube, adopt the rolling of PQF hot continuous rolling unit; Be greater than for diameter
20G weldless steel tube, adopt the oblique rolling extension diameter tube rolling unit rolling of PQF hot continuous rolling+720;
The wall thickness of above-mentioned controlled rolling is that the index of mechanical property of the 20G weldless steel tube of 16～40mm is as follows:
Yield strength Rel: >=245MPa,
The yield strength Rel of 450 DEG C: >=150MPa,
Tensile strength Rm:410～550MPa,
Summer is than V-type impelling strength: 20 DEG C of longitudinal full-scale Charpy-V impact power >=40J, and 20 DEG C 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 the advantage that uses the method:
(1) in 20G steel grade, add trace 0.03～0.07%V, to improve the yield strength of thick wall hot-rolled pipe, the scope of 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%, to improve impelling strength.The wall thickness weldless steel tube property indices that adopts this steel grade to produce reaches the requirement of high pressure boiler tube completely;
(2) finishing temperature, at 850～950 DEG C, has improved the mechanical property of steel pipe;
(3) controlled rolling, compared with conventional hot rolling+normalizing heat treatment technique, has been 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
Manufacture method with heavy wall 20G weldless steel tube in controlled rolling replacement normalizing production of the present invention is illustrated 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
By the weight proportion of 20G steel steel grade element 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, impurity element trace;
After batching through electric furnace or converter steelmaking, in tapping process, add Si-Ca-Ba to carry out pre-deoxidation processing, molten steel carries out 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 heating-furnace temperature control is 1250～1290 DEG C, and piercing temperature control is 1200～1250 DEG C, and 850～950 DEG C of finishing temperatures are cooling, sawing;
Be less than or equal to for diameter
20G steel pipe, adopt the rolling of PQF hot continuous rolling unit; Be greater than for diameter
20G steel pipe, adopt the oblique rolling extension diameter tube rolling unit rolling of PQF hot continuous rolling+720;
The wall thickness of above-mentioned controlled rolling is that the index of mechanical property of the 20G weldless steel tube of 16～40mm is as follows:
Yield strength Rel: >=245MPa,
The yield strength Rel of 450 DEG C: >=150MPa,
Tensile strength Rm:410～550MPa,
Summer is than V-type impelling strength: 20 DEG C of longitudinal full-scale Charpy-V impact power >=40J, and 20 DEG C of horizontal full-scale Charpy-V impact power >=27J,
Unit elongation: >=24%,
Grain fineness number: more than 5 grades.
20G steel in the manufacture method that replaces heavy wall 20G weldless steel tube in normalizing production with controlled rolling of the present invention, 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, impurity element trace.
Chief component composition is chosen and 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 taking solution strengthening effect as main.Research shows, in steel, manganese content is how many and intensity is proportional, 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 the best manganese content of 20G 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, the vanadium micro-alloyed steel of common nitrogen content can produce comparatively significantly precipitation strength effect 800 DEG C 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.For the content of this this steel grade design V is 0.03～0.07%, the best is 0.04～0.06%.
Chrome molybdenum: in carbon steel, the chrome molybdenum of trace is generally 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, it is 0.5% harmful to enduring quality again that content is greater than, therefore the content of nickel be controlled at≤0.30%.Copper can improve intensity and the erosion resistance of steel, but the segregation of copper is the hot-short phenomenon causing, its residual volume control is≤0.25% for this reason.
Aluminium: in steel, residual aluminum is mainly derived from deoxidation products, unnecessary aluminium is combined with nitrogen, crystal grain thinning.But Al element impels carbon steel greying, and the enduring quality of greying infringement steel.Therefore, in the design's 20G steel, the control of Al content is≤0.025%.
Sulphur phosphorus: the toughness of sulphur, phosphorus infringement steel, lower sulphur phosphorus content control has ensured the low-temperature flexibility of 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, impurity element trace.Specifically as shown in table 1.
Table 1 chemical component table (wt%)
After batching through electric furnace or converter steelmaking, in tapping process, add Si-Ca-Ba to carry out pre-deoxidation processing, molten steel carries out 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 heating-furnace temperature control is 1250～1290 DEG C, and piercing temperature control is 1200～1250 DEG C, and 850～950 DEG C of finishing temperatures are cooling, sawing.
Be less than or equal to for diameter
20G steel pipe, adopt the rolling of PQF hot continuous rolling unit; Be greater than for diameter
20G steel pipe, adopt the oblique rolling extension diameter tube rolling unit rolling of PQF hot continuous rolling+720.
The wall thickness of above-mentioned controlled rolling is that the index of mechanical property of the 20G weldless steel tube of 16～40mm is as follows:
Yield strength Rel: >=245MPa,
The yield strength Rel of 450 DEG C: >=150MPa,
Tensile strength Rm:410～550MPa,
Summer is than V-type impelling strength: 20 DEG C of longitudinal full-scale Charpy-V impact power >=40J, and 20 DEG C 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, impurity element trace.Working control alloying constituent is as shown in table 2 below.
After batching through electric furnace or converter steelmaking, in tapping process, add Si-Ca-Ba to carry out pre-deoxidation processing, molten steel carries out 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 heating-furnace temperature control is 1260 DEG C, and piercing temperature control is 1230 DEG C, 850 DEG C of finishing temperatures, and then cold bed is cooling, sawing.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 DEG C 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, impurity element trace.Working control alloying constituent is as shown in table 4 below.
After batching through electric furnace or converter steelmaking, in tapping process, add Si-Ca-Ba to carry out pre-deoxidation processing, molten steel carries out 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 heating-furnace temperature control is 1230 DEG C, and piercing temperature control is 1200 DEG C, 950 DEG C of finishing temperatures, and then cold bed is cooling, sawing.
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 DEG C 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, impurity element trace.Working control alloying constituent is as shown in table 6 below.
After batching through electric furnace or converter steelmaking, in tapping process, add Si-Ca-Ba to carry out pre-deoxidation processing, molten steel carries out 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 heating-furnace temperature control is 1230 DEG C, and piercing temperature control is 1180 DEG C, 950 DEG C of finishing temperatures, and then cold bed is cooling, sawing.
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 DEG C 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 meets the requirement of 20G weldless steel tube completely, 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, shorten Production Flow Chart and time, therefore improve production efficiency.Secondly, originally said with respect to the one-tenth of the trace vanadium adding, the total manufacturing cost of steel pipe still has substantial degradation, and has good popularizing application prospect.
Claims (1)
1. a manufacture method that replaces heavy wall 20G weldless steel tube in normalizing production with controlled rolling, the method is to be to weight proportion: 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 steel grade of impurity element trace; After batching through electric furnace or converter steelmaking, in tapping process, add Si-Ca-Ba to carry out pre-deoxidation processing, molten steel carries out 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 base; It is characterized in that: the operation of rolling of the method is:
Scale continuously cast bloom after the assay was approved heats in rotary heating furnace, and heating-furnace temperature control is 1250～1290 DEG C, and piercing temperature control is 1200～1250 DEG C, 850～950 DEG C of finishing temperatures, and cooling, 20G weldless steel tube is made in sawing;
Be less than or equal to for diameter
20G weldless steel tube, adopt the rolling of PQF hot continuous rolling unit; Be greater than for diameter
20G weldless steel tube, adopt the oblique rolling extension diameter tube rolling unit rolling of PQF hot continuous rolling+720;
The wall thickness of above-mentioned controlled rolling is that the index of mechanical property of the 20G weldless steel tube of 16～40mm is as follows:
Yield strength Rel: >=245MPa,
The yield strength Rel of 450 DEG C: >=150MPa,
Tensile strength Rm:410～550MPa,
Summer is than V-type impelling strength: 20 DEG C of longitudinal full-scale Charpy-V impact power >=40J, and 20 DEG C of horizontal full-scale Charpy-V impact power >=27J,
Unit elongation: >=24%,
Grain fineness number: more than 5 grades.
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| 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 |
| CN104593543B (en) * | 2015-01-07 | 2016-08-24 | 宁波万冠精密铸造厂 | A kind of method for making steel |
| 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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| Publication number | Priority date | Publication date | Assignee | Title |
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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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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. |