CN102978307B - Process for reducing production of pipeline steel - Google Patents
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- CN102978307B CN102978307B CN201210506563.9A CN201210506563A CN102978307B CN 102978307 B CN102978307 B CN 102978307B CN 201210506563 A CN201210506563 A CN 201210506563A CN 102978307 B CN102978307 B CN 102978307B
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Abstract
The invention discloses a process for reducing production of pipeline steel, belonging to the technical field of metallurgy. The process comprises the following steps of: performing desulfuration treatment on molten iron during a blast furnace iron-making process; simplifying an ingredient design by means of reducing the dosage of alloying elements during the iron-making process to increase an alloy yield and the like; controlling the shape and the quantity of inclusions via the processes of calcification treatment, soft argon bag bottom-blowing treatment and the like; and carrying out a two-phase control rolling and laminar cooling technology during a steel-rolling phase to obtain an organization which is composed of polygonal ferrite, granular bainite and a small amount of pearlite. The process is suitable for pipeline steel corresponding to S485, S450, S415, S390 and S360, and pipeline steel corresponding to X70, X65, X60, X56, X52 and the like in the relevant standards of API (American Petroleum Institute). The process has the advantages that the technical processes of molten iron pre-treatment and RH refining are reduced relative to the traditional process, and a good means is provided for small and medium-sized iron and steel enterprises for producing high-grade pipeline steel with a narrow section and a thin gauge.
Description
Technical field
The invention belongs to pipe line steel technical field, particularly a kind of technique of minimizing production flow line steel.Be applicable to the corresponding pipe line steels such as X70, X65 in S485, S450, S415, S390, S360 and API relevant criterion, X60, X56, X52.
Background technology
The theoretical investigation of China's pipe line steel is accompanied by the progress of pipework construction and develops.Along with carrying out of national basis tackling key problem, applied basic research and technology development projects such as 2003 " the great technique fundamental researchs of high-strength line-pipe steel ", research and the production of China's pipe line steel develop rapidly.Be accompanied by the completion of transfering natural gas from the west to the east first phase, the second stage of the project, China has realized the S485 level pipe line steel of technical grade and has produced, and has broken the external long-term monopolization to high-grade pipe line steel, and realizes outlet.But still there is more difference in the understanding to S485 level acicular ferrite of pipeline steel weave construction.In addition, with scientific and technological progress and the attention to resource, environment, how to utilize the ferrous materials of simple chemical composition, simplify production technique link, by the control of the course of processing, effectively improve the over-all properties of material, thereby reduce material usage quantity, improve work-ing life, realize the minimizing of pipe line steel and produce, become the main direction of present steel investigation of materials.
Although S485 level pipe line steel can be realized suitability for industrialized production at present; but most of manufacturing enterprises all adopt the technological process of hot metal pretreatment+converter+LF refining+RH refining+continuous casting+controlled rolling and controlled cooling; this complex technical process; control parameter is more; facility investment is excessive, in being unfavorable for, little steel enterprise scale produces.Especially high as RH refining furnace facility investment expense, utilization coefficient is low.And transfering natural gas from the west to the east the third stage of the project is about to go into operation, each branch line and urban pipe network still need a large amount of S485 levels and low-level narrow section (685mm ~ 1250mm), thin specification (6 ~ 12mm) pipe line steel, these specification limits adopt large unit production cost too high, need a kind of new technique to reduce S485 and following other small dimension pipe line steel of level, constantly adapt to the demand in market.
Although the domestic patent about pipe line steel is a lot, as the technique of converter-RH-LF-continuous casting production flow line steel, application number: 200810020314.2, comprise converter process and terminal control, stay oxygen tapping technique, RH decarburization degasification technique, RH deoxidation alloying process and LF sulfur removal technology.For another example high-intensity high-tenacity line of pipes steel and preparation method thereof, application number: 200410013265.1, the composition of pipe line steel and steel rolling temperature are controlled to technique and set forth.But these patents are just set forth production technique or the chemical composition of pipe line steel from local technique or process, go back neither one patent ferrous metallurgy is described in detail from the whole process of ironmaking, steel-making, steel rolling and Composition Design and structural state.
Summary of the invention
The object of the present invention is to provide a kind of technique of minimizing production flow line steel, with respect to traditional technology, reduced the technological process of hot metal pretreatment and RH refining, be in, the little steel enterprise excellent means of producing narrow section (685～1250mm), thin specification (6～12mm) high-grade pipe line steel.
The present invention is mainly by carrying out desulfurization processing to molten iron in blast furnace ironmaking process, the consumption that reduces alloying element in steelmaking process improves the means such as yield of alloy and simplifies Composition Design, and by technology controlling and process inclusion morphology and quantity such as soft blow processing at the bottom of calcification processing, argon gas bag, in the steel rolling stage, by two-stage control rolling and laminar flow cooling technology, obtain the tissue that polygonal ferrite, granular bainite and a small amount of perlite form.Be applicable to the corresponding pipe line steels such as X70, X65 in S485, S450, S415, S390, S360 and API relevant criterion, X60, X56, X52.The technical parameter of skill step and control is as follows:
1, blast-furnace smelting: when guaranteeing Proper Burden Constitution, need to control 1440 ~ 1480 ℃ of the molten iron temperatures of blast furnace, the physics heat energy that also will guarantee blast furnace is that the silicone content in molten iron fluctuates between 0.40%～0.70%, guarantee the basicity 1.2～2 of charging of blast furnace, the sulphur content 0 ~ 0.025% that finally can guarantee to come out of the stove in molten iron simultaneously.
2, converter steelmaking: while guaranteeing tapping, slag basicity fluctuates between 3.5～4, phosphorus content 0～0.020%, sulphur content is controlled at 0～0.020%.Atm number during tapping (1.0 ~ 1.5MPa) stirs, and guarantees the abundant melting of top slag and inclusion floating effect.
3, LF refining: feed pure calcium line before going out refining furnace, guarantee Ca/Al:0.09～0.13; Feed afterwards 100～200 meters of titanium wires, guarantee that finished product Ti content is at 0.015%～0.025%; During line feeding, ladle adopts blowing argon gas to carry out weak stirring, with molten steel face, springs up, and molten steel is exposed being advisable not, guarantees effectively clean 10～15 minutes soft blow time after line feeding;
4, continuous casting: wrap 5～25 ℃ of superheating temperature in assurance, must guarantee the unlatching of induction stirring simultaneously, prevent the generation of strand segregation.
5, process furnace: the steel billet after continuous casting, need stack in workshop, slowly cool to normal temperature～200 ℃ and can send into process furnace and heat.
6, steel rolling: guarantee that finishing mill temperature in is controlled at 970～1035 ℃, the temperature of finishing mill outlet is controlled at 810～840 ℃, and curling temperature is controlled at 600 ± 15 ℃, guarantees that speed of cooling is at 15～17 ℃/s simultaneously.Obtain the most at last the tissue that polygonal ferrite, granular bainite and a small amount of perlite form.
The principle of cardinal principle of the present invention or the sublimate of iron and steel, by simplifying whole pipeline steel smelting technological process, the reduction alloy material particularly process of high price alloy material consumption reaches the object that the high-grade pipe line steels such as S485 are produced in minimizing.
In the blast furnace ironmaking stage, reasonably prepare burden, control blast furnace temperature the process of desulfurizing iron is advanceed to before the process of blast furnace casting, thereby omitted the process procedure of hot metal pretreatment, thereby reduce the burden of converter desulfurization.Guarantee in pipe line steel that sulphur content is lower than rational level.
In convertor steelmaking process, by controlling the measures such as the liquid steel temperature of converter and basicity, carry out dephosphorization treatment, in the process of alloying, no longer add molybdenum alloy and vanadium alloy simultaneously, reduce the alloy consumption in pipe line steel, titanium alloy adds raising titanium alloy recovery rate after refining finishes, adopt the operational path of low-carbon high-manganese, reasonably allocate the ratio of various elements, thereby reach the object that reduces cost of alloy.
Secondary desulfuration processing is carried out in the smelting of logical LF refining furnace, completes the process of removal of inclusions simultaneously.Because pipe line steel mechanical property does not conform to, great majority are too high relevant with the rank of inclusion, by first feed calcium line before refining procedure finishes, inclusion carried out to calcification processing, make it to be easy to floating.Thereby in ladle, feed afterwards the recovery rate that a certain amount of titanium wire guarantees titanium alloy.In the continuous casting stage, adopt electromagnetic agitating technology, guarantee that the segregation of strand is controlled at rational scope.
All pipeline steel continuous casting blank all adopts cold charging technique, guarantee that continuously cast bloom arrives austenitic twice complete phase transition process through austenite again to ferrite, when completing structural transformation, guarantee Nb (C, N), Ti (C, N) thus fully separate out the object that reaches precipitation strength.
The temperature in, temperature out and the coiling temperature that at rolling sequence, guarantee finishing mill to guarantee the object of two-stage control rolling, adopt the rational type of cooling simultaneously, obtain desirable tissue, make the abundant refinement of tissue of pipe line steel.
Compared with prior art, the invention has the beneficial effects as follows:
1, for middle-size and small-size Dai Gang manufacturing enterprise, the section of rolling mills is conventionally direct 650 to 1500mm, there is no the main equipments such as hot metal pretreatment or RH refining furnace, this patent has been simplified the production process of pipe line steel, reduced the production cost of high-grade pipe line steel, solved middle-size and small-size Dai Gang manufacturing enterprise equipment not enough, the problem that is difficult to produce high-grade pipe line steel.
2, the present invention has reduced and has adopted the method that adds titanium alloy after refining, has guaranteed titanium alloy recovery rate, no longer adds molybdenum alloy and vanadium alloy simultaneously, has reduced the cost of alloy.
3, pass through cooling controlling and rolling controlling process, obtained the tissue of ferrite+perlite+a small amount of bainite, with respect to the metallographic structure of conventional needle columnar ferrite, represented more excellent toughness, the low temperature ductile-brittle transition temperature of the S485 pipe line steel of the method suitability for industrialized production is FATT
50arrived below-70 ℃, the product of producing than common process is low nearly 30 ℃.
Accompanying drawing explanation
Fig. 1 is process flow sheet of the present invention.
Embodiment
Embodiment 1
Certain enterprise is by the S485 pipe line steel of following explained hereafter, and cross dimensions is 12.0*1020mm.
1, blast-furnace smelting: 1461 ℃ of the molten iron temperatures of blast furnace, silicone content is 0.48%, and the basicity of charging of blast furnace is 1.8, and sulphur content is 0.017%.
2, converter steelmaking: slag basicity is 3.75, phosphorus content 0.018%, sulphur content is controlled at 0.015%.
3, LF refining: feed 185 meters of pure calcium lines, 123 meters of feeding titanium wires, effectively clean 12.5 minutes soft blow time;
4, continuous casting: 1552 ℃ of teeming temperatures, must guarantee the unlatching of induction stirring simultaneously, prevent the generation of strand segregation.
5, process furnace: the whole cool to room temperature of steel billet are sent into process furnace.
6, steel rolling: guarantee that finishing mill temperature in is controlled at 1015 ℃, the temperature of finishing mill outlet is controlled at 823 ℃, and curling temperature is controlled at 605 ℃, guarantees that speed of cooling is at 16 ℃/s simultaneously.Obtain the most at last the tissue that polygonal ferrite, granular bainite and a small amount of perlite form.。
In national steel products Quality Supervision and Inspection Center, test result is as follows, and specific chemical composition is as shown in table 1.
Table 1 S485, δ 12mm chemical composition analysis result and standard regulation contrast (wt./%), surplus is: Fe
Note: carbon equivalent calculation formula:
(1) when carbon content (Wt.%) is greater than 0.12, carbon equivalent calculating formula is:
(2) when carbon content (Wt.%) is less than or equal to 0.12, carbon equivalent calculating formula is:
The horizontal Charpy-V impact power of steel plate is 188.8J, and the ductile-brittle transition temperature of steel plate is-72.2 ℃, and the stretch test result of steel plate is as shown in table 2.
Table 2 S485, δ 12mm tensile mechanical properties test-results
| S485, δ 12mm steel plate | R m(MPa) | R t0.5(MPa) | R t0.5/R m | A(%) |
| (GB/T?14164-2005) | 570~755 | 485~620 | / | ≥16 |
| Horizontal sample | 615 | 544 | 0.88 | 33.5 |
| (50×38mm) | 616 | 545 | 0.88 | 33 |
Reference standard GB/T 14164-2005 < < petroleum gas delivering pipe is analyzed judgement with hot rolled broad steel strip > > to test-results, and conclusion is as follows:
1) tough brittle transition temperature FATT
50for-72.2 ℃.
2) steel plate S485, the mother metal highest hardness of δ 12mm steel plate is 201HV
10, that the hardness of different zones differs is less, it is comparatively even to distribute.
3) steel plate microstructure is comprised of polygonal ferrite, granular bainite and a small amount of perlite, and grain size number is 12.5 grades.
4) chemical composition of steel plate, tensile mechanical properties, impact mechanical performance, non-metallic inclusion rank and guided bend test result all meet the demand of technical standard of relevant criterion.
Finally explanation, above embodiment is only unrestricted so that technical scheme of the present invention to be described.Although the present invention is had been described in detail with reference to preferred embodiment, those of ordinary skill in the art is to be understood that, can carry out the modification in parameter area or be equal to replacement technical scheme of the present invention, and not departing from aim and the scope of technical solution of the present invention, it all should be encompassed in the middle of claim scope of the present invention.
Claims (2)
1. a technique for minimizing production flow line steel, is characterized in that, the technical parameter of processing step and control is as follows:
(1) blast-furnace smelting: control 1440 ~ 1480 ℃ of the molten iron temperatures of blast furnace, the silicone content in molten iron between 0.40%～0.70%, the basicity 1.2～2 of charging of blast furnace simultaneously, the sulphur content 0 ~ 0.025% of finally coming out of the stove in molten iron;
(2) converter steelmaking: during tapping slag basicity between 3.5～4, phosphorus content 0～0.020%, sulphur content is controlled at 0～0.020%; During tapping, 1.0 ~ 1.5MPa stirs, and makes the abundant melting of top slag and inclusion floating;
(3) LF refining: feed pure calcium line, Ca/Al:0.09～0.13 before going out refining furnace; Feed afterwards 100～200 meters of titanium wires, finished product Ti content is at 0.015%～0.025%; During line feeding, ladle adopts blowing argon gas to carry out weak stirring, and molten steel face is sprung up, and molten steel is not exposed, clean 10～15 minutes soft blow time after line feeding;
(4) continuous casting: 5～25 ℃ of middle bag superheating temperature, induction stirring is opened simultaneously, prevents strand segregation;
(5) process furnace: the steel billet after continuous casting is stacked in workshop, slowly cools to normal temperature～200 ℃, sends into process furnace and heats;
(6) steel rolling: finishing mill temperature in is controlled at 970～1035 ℃, the temperature of finishing mill outlet is controlled at 810～840 ℃, and curling temperature is controlled at 585～615 ℃, and speed of cooling is at 15～17 ℃/s simultaneously; Obtain the most at last the tissue that polygonal ferrite, granular bainite and a small amount of perlite form.
2. the technique of minimizing production flow line steel according to claim 1, is characterized in that, this technique is applicable to the corresponding pipe line steel of X70, X65, X60, X56, X52 in S485, S450, S415, S390, S360 and API relevant criterion.
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| CN107881428B (en) * | 2017-10-24 | 2019-09-24 | 德龙钢铁有限公司 | A kind of production method reducing hot-rolled coil Q345B dendritic segregation |
| CN110541114B (en) * | 2019-10-08 | 2021-02-23 | 宝武集团鄂城钢铁有限公司 | Smelting method of high-nitrogen high-sulfur low-aluminum steel |
| CN115044821B (en) * | 2022-06-17 | 2023-11-17 | 德龙钢铁有限公司 | Method for reducing inclusion grade of hot rolled wide steel strip for gas transmission pipeline below L360 level |
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