CN103981461A - X90 pipeline steel wide and thick plate and production method thereof - Google Patents

Abstract

The invention relates to an X90 pipeline steel wide and thick plate and a production method thereof, belonging to the technical field of low-carbon microalloy steel. The wide and thick plate comprises the following components in percentage by weight: 0.06-0.10% of C, 0.20-0.50% of Si, 1.50-1.80% of Mn, at most 0.010% of P, at most 0.003% of S, 0.04-0.06% of Nb, 0.04-0.06% of V, 0.010-0.020% of Ti, 0.15-0.30% of Ni, 0.15-0.30% of Cr, 0.10-0.30% of Mo, 0.020-0.05% of Als, and the balance of Fe and inevitable impurities. The technique comprises the following steps: predesulfurizing blast furnace molten iron, smelting in a converter, carrying out LF+RH refinement, continuously casting a plate blank, heating the plate blank, rolling by a 4300 rolling mill, carrying out ACC quick cooling, cooling in pile, sampling, inspecting, warehousing and shipping. The steel plate has the advantages of high strength, excellent low-temperature toughness and excellent dynamic tear resistance.

Description

A kind of X90 pipe line steel Wide and Thick Slab and production method thereof

Technical field

The invention belongs to low-carbon micro steel-alloy technical field, particularly relate to a kind of X90 pipe line steel Wide and Thick Slab and production method thereof, is a kind of Eco-power X90 pipe line steel Wide and Thick Slab, is applicable to the transport pipe construction of oil, Sweet natural gas.

Background technology

Oil and gas is the grand strategy goods and materials of national economy, and energy growth adds composition optimizes adjustment, has driven the development in an all-round way of industrial gas oil.Pipeline carry be by oil and gas from remote exploitation the important way of carrying to the long distance of end user terminal, high-pressure large-caliber long-distance transport pipes have become most economical, the safest method of shipment of oil gas transport.Data shows, the raising of transfer pressure can be by improving pipeline steel tube intensity rank and increasing wall thickness, and wall thickness increase certainly will bring the increase of steel pipe weight, and construction cost improves.In the case, be only improved pipe line steel level, just can reduce thickness of steel pipe, saving steel, the cost of reduction pipe-line construction.Generally, steel pipe expense accounts for the 25%-30% of whole pipeline investment.

In recent years, along with the construction in succession of the engineerings such as China's transfering natural gas from the west to the east, Central Asia pipeline, China is made outstanding achievements in the exploitation of X70/X80 high-strength line-pipe steel, ranked among the ranks of the advanced pipeline in the world.At present, China has begun to take shape across thing, has stretched from the north to the south, covered the whole nation, has been communicated with overseas energy pipe network.Along with the continuous increase of China's Demand of Oil & Gas, to compare with the energy demand of China and the pipe level of advanced country, China's pipe-line construction also has huge demand and potentiality.Meanwhile, for reducing as much as possible land seizure and construction cost, the strong economical pipe line steel research and development of superelevation make pipeline more the conveying of high pressure become possibility.

2014, organizing nation of group of CNPC interior conduit and metallurgy industry expert held economical X90 discussion, can on chemical composition requirement, performance index adjustment, buying pattern, circumferential weld and the economic feasibility of economical X90 pipe line steel have been discussed.Economical X90 pipe line steel development is not only the upgrading of existing X80 pipe line steel is substituted with low cost and promoted the use of, but also can be the relevant utility data of X100/X120 higher category pipe line steel accumulation, significant to Chinese pipe-line construction.The difficult point of economical X90 pipe line steel Wide and Thick Slab exploitation is that cost compares and increase under less prerequisite compared with X80, realizes the General Promotion of armor plate strength and toughness, has good weldability and arrest toughness.

Summary of the invention

The object of the present invention is to provide a kind of X90 pipe line steel Wide and Thick Slab and production method thereof, design and rolling technology by reasonable component, use 300mm continuously cast bloom production economy type X90 pipe line steel hot rolled slab, not only product over-all properties meets the demands, and has good low-temperature flexibility and welding property.Steel plate tissue is mainly bainite structure+martensite+a small amount of M-A constituent element, and homogeneous microstructure is tiny, and grain fineness number is more than 13 grades.

The composition (by weight percentage) of steel plate of the present invention is:

C:0.03-0.09%, Si:0.10-0.40%, Mn:1.30-2.0%, P≤0.015%, S :≤0.003%, Nb:0.05-0.10%, V :≤0.06%, Ti:0.010-0.040%, Ni:0.10-0.50%, Cr :≤0.50%, Mo :≤0.50%, Al:0.010-0.040%, surplus is Fe and inevitable impurity.

Composition Design of the present invention is based on following understanding:

C: for ensureing that economical X90 pipe line steel has excellent welding property and good low-temperature flexibility, carbon content need be strict controlled in below 0.09%.

Si is effective deoxidant element, can also play strengthening effect, but Si too high levels can make plasticity and the toughness drop of steel, and therefore setting its scope is 0.15%～0.40%.

Mn is solution strengthening element important in steel, can reduce transformation temperature, and thinning microstructure substructure is improved toughness in strengthening steel plate; Meanwhile, can improve hardening capacity.

P, S are detrimental impurity element, adopt calcium to process and PURITY STEEL PRODUCTION TECHNOLOGY, strictly control the inclusion such as phosphorus, sulphur in steel.

Nb, Ti are solution strengthening elements, are again carbonitride forming elements, and in heating steel billet and the operation of rolling, pinning austenite grain boundary also stops austenite crystal excessively to be grown up, but its too high levels can affect toughness and weldability.

Cr can effectively increase the hardening capacity of steel, improves mechanical property, but too high levels has disadvantageous effect to material weldability.

Ni, Cu play solution strengthening effect, can also improve solidity to corrosion, and Ni can also improve the low-temperature flexibility of steel simultaneously.

Mo can improve the low-temperature flexibility of steel, stronger bainitic transformation control element.In high strength microalloy steel, add appropriate Mo element and just can obtain obvious bainite structure, because phase transformation changes to low temperature direction, can make the further refinement of phase-change organization simultaneously, significantly improve the toughness and tenacity of steel, also can effectively reduce yield tensile ratio simultaneously.Because Mo is precious metal element, therefore in the present invention, Mo content is controlled at 0.10～0.25% scope.

The existence of N can worsen the toughness of mother metal and welded heat affecting zone, and its content is no more than 0.006% and is advisable.

The production of steel plate of the present invention comprises: blast-melted → molten iron pre-desulfurization → converter smelting → LF+RH refining → sheet billet continuous casting → heating of plate blank → 4300 mill milling → ACC cooling → cooling in heap → sampling fast, inspection → warehouse-in, shipping.

At slab casting+controlled rolling+Controlled cooling process, in process, control parameter and be:

(1) the chemical composition smelting molten steel by steel plate is poured into the thick continuously cast bloom of 300mm;

(2) by walking beam heating furnace by heating steel billet to 1150～1200 DEG C of design temperatures, heat-up time, 280-350min, ensured steel billet abundant austenitizing;

(3) steel billet enters 4300mm mill milling after coming out of the stove, and adopts recrystallization zone+non-recrystallization district two stage rolling when rolling, and doubly, rough rolling step and finish rolling stage parameter are as follows for the 2-4 that holding gauge is finished product thickness:

Rough rolling step: start rolling temperature: 1000-1100 DEG C, roll speed: 1.0-3.5m/s, rolling torque: 2000-3200kNm; Tiny for obtaining, uniform microstructure, roughing needs bonding pass deformation rate 10-35%.

The finish rolling stage: adopt low temperature open rolling, start rolling temperature: 760-820 DEG C, finishing temperature: 720-800 DEG C, roll speed: 2.0-4.0m/s.

(4) roll rear steel plate cooling by ultrafast cold UFC+ laminar flow ACC associating, begin to cool down temperature and be controlled at 730-790 DEG C, final cooling temperature is controlled at 200-350 DEG C, make full use of cooling apparatus ability, rate of cooling 25-40 DEG C/s, with the abundant crystal grain thinning of large cooling rate, improve steel plate obdurability;

(5) the cooling rear stacking slow cooling of steel plate, heap cool time 12-24 hour.

The economical X90 pipe line steel of producing by above-mentioned operation, steel plate has high intensity, good low-temperature flexibility and anti-dynamic tear energy power.

Brief description of the drawings

Fig. 1 is X90 pipe line steel Wide and Thick Slab optics Electronic Speculum tissue.

Fig. 2 is X90 pipe line steel Wide and Thick Slab scanning electron microscope tissue.

Embodiment

Economical X90 pipe line steel Wide and Thick Slab and manufacture method thereof according to the present invention are smelted in 100 tons of converters, and are cast into the continuously cast bloom of 300mm × 2400mm × 2700mm, on 4300mm Heavy Plate Rolling Line, are rolled.Chemical composition is as shown in table 1, and process system is as shown in table 2, and mechanical property of steel plate is as shown in table 3.

The chemical composition wt% of table 1 steel plate

Embodiment	O	Si	Mn	P	S	Al	Nb	Ni	Ti	Cr	Cu	Mo	N	H
															Embodiment 1	0.045	0.25	1.80	0.011	0.0013	0.034	0.078	0.175	0.014	0.21	0.20	0.15	0.004	0.0001
Embodiment 2	0.056	0.24	1.79	0.010	0.0008	0.036	0.063	0.175	0.014	0.19	0.21	0.12	0.003	0.0001
															Embodiment 3	0.060	0.22	1.75	0.009	0.0011	0.03	0.055	0.172	0.015	0.23	0.19	0.18	0.002	0.0001
Embodiment 4	0.070	0.23	1.70	0.008	0.0009	0.035	0.050	0.170	0.015	0.20	0.21	0.13	0.004	0.0002

Table 2 process system

The economical X90 pipe line steel that the present invention produces has the panel construction that spacing is less, the tiny M-A island that distributing between lath, and there is high density dislocation.Fig. 1 and Fig. 2 are respectively X90 metallograph under optics and scanning electron microscope.

Table 3 mechanical property of steel plate

The present invention by adopt low temperature depress greatly and ultrafast cold+the cooling very low temperature phase transformation of laminar flow, fully refinement phase-change organization, ensure that the rear phase-change organization of X90 pipe line steel distortion is tiny bainite structure+martensitic stucture, ensure that steel plate can have high intensity, there is good low-temperature impact toughness and anti-low-temperature dynamic is torn ability simultaneously.The economical X90 pipe line steel of the present invention, can be widely used in petroleum-gas pipeline engineering construction, and the construction cost that reduces line of pipes is had to obvious effect.

Claims (2)

1. an X90 pipe line steel Wide and Thick Slab, is characterized in that, composition weight percentage is:

C:0.06-0.10%, Si:0.20-0.50%, Mn:1.50-1.80%, P≤0.010%, S :≤0.003%, Nb:0.04-0.06%, V:0.04-0.06%, Ti:0.010-0.020%, Ni:0.15-0.30%, Cr:0.15-0.30%, Mo:0.10-0.30%, Als:0.020-0.05%, surplus is Fe and inevitable impurity.

2. a production method for X90 pipe line steel Wide and Thick Slab claimed in claim 1, technique comprises: blast-melted → molten iron pre-desulfurization → converter smelting → LF+RH refining → sheet billet continuous casting → heating of plate blank → 4300 mill milling → ACC cooling → cooling in heap → sampling fast, inspection → warehouse-in, shipping; It is characterized in that, the technical parameter of controlling in slab casting+controlled rolling and controlled cooling technological process is:

(1) the chemical composition smelting molten steel by steel plate is poured into the thick continuously cast bloom of 300mm;

(2) by walking beam heating furnace by 1150～1200 DEG C of heating steel billets, heat-up time, 280-350min, ensured steel billet austenitizing;

(3) steel billet enters 4300mm mill milling after coming out of the stove, and adopts recrystallization zone+non-recrystallization district two stage rolling when rolling, and doubly, rough rolling step and finish rolling stage parameter are as follows for the 2-4 that holding gauge is finished product thickness:

Rough rolling step: start rolling temperature: 1000-1100 DEG C, roll speed: 1.0-3.5m/s, rolling torque: 2000-3200kNm; Roughing needs bonding pass deformation rate 10-35%;

Finish rolling stage: start rolling temperature: 760-820 DEG C, finishing temperature: 720-800 DEG C, roll speed: 2.0-4.0m/s;

(4) roll rear steel plate cooling by ultrafast cold UFC+ laminar flow ACC associating, begin to cool down temperature and be controlled at 730-790 DEG C, final cooling temperature is controlled at 200-350 DEG C, rate of cooling 25-40 DEG C/s, with crystal grain thinning, improves steel plate obdurability;

(5) the cooling rear stacking slow cooling of steel plate, heap cool time 12-24 hour.