CN103498072A - High-strength high-impact-toughness titanium alloy used for oil well and gas well, and preparation method thereof - Google Patents

Abstract

The invention relates to high-strength high-impact-toughness titanium alloy comprising the chemical components of, by weight: 4.0-9.0% of Al, 0.5-5.0% of Mo, 1-5% of Nb, 1-5% of Zr, and balance of Ti. The preparation method comprises mixing, electrode rod pressing, vacuum consumption and twice smelting, such that an alloy ingot is prepared. The titanium alloy provided by the invention assists in well solving a problem of poor H2S and CO2 corrosion resistance of an existing P110 steel oil well and gas well pipe material. Also, 40% weight reduction can be realized, such that drilling rig power is greatly reduced. With the alloy, petroleum and natural gas exploration capacity of our nation can be greatly improved.

Description

A kind of oil, gas well high strength high impact toughness titanium alloy and preparation method

Technical field

The invention belongs to the titanium alloy material field, especially relate to a kind of oil, gas well high strength high impact toughness titanium alloy and preparation method.

Background technology

Nickel-based alloy pipe and the high chromium rust free steel pipes of using in oil, Sweet natural gas probing and recovery process more.But in short supply along with petroleum resources, the oil that hole condition is better, the degree of depth is little, gas well are few, increasing oil, gas well concentrate on the more severe area of underground environment, as Sichuan Basin, main exploiting field of current China is exactly this situation, the oil in this area, gas well are rich in H2S, CO2, and hole condition is quite severe.The situation that corrosion is revealed often appears in high chromium-stainless steel steel pipe commonly used at present, brings huge financial loss to production unit and the people.

Except the problem of corrosion resistance nature deficiency, adopt nickel-based alloy pipe and stainless steel tube as oil well pipe, also have following problem: 1) in nickel-base alloy, a large amount of nickel used is the national strategy resource, the consumption of oil well pipe estimates that 2015 annual requirements will reach 6,000,000 tons, and a large amount of uses of nickel are unfavorable to national security.2) proportion of nickel-based alloy pipe and stainless steel tube is larger, to having relatively high expectations of supporting rig.Oil well as the darkest as Xinjiang region reaches 7000 meters, all uses stainless steel tube or nickel-based alloy pipe, and rig power will reach quite high stage and just can meet the demands.Oil, gas well is more urgent to the demand of lightweight, Materials with High Strength.

Since nineteen ninety-five, bring into use titanium alloy abroad on oil platform, in recent years, the exploitation of titanium alloy oil well pipe also receives more concern.Adopt the standby oil of titanium alloys, gas well pipe to there is application prospect preferably.At first titanium alloy has good corrosion resistance nature, and anti-H2S, CO2 corrosive nature are also very outstanding.Simultaneously the proportion of titanium alloy be only 57% of steel proportion, adopts darker that identical rig can make oily, gas well, thereby can save a large amount of front-end investments.But oil, the gas well working condition is severe, to tubing, requires very high.Design concept based on " leaking before breaking ", except pipe material being proposed to strict requirement of strength, also proposed the impact property requirement.The requirement of P110 grade of steel of take is example, and corresponding material should meet and requires as table 1:

Table 1 P110 steel level oil conduit mechanical property requirements

The impact of other grade of steel is also identical with this index.With steel, compare, the impact property of titanium alloy is lower.Simultaneously, in general, titanium alloy intensity is higher, and impact property is just lower, and meeting above-mentioned requirements has larger difficulty.

The ripe trade mark of the titanium alloy that China develops voluntarily is less, and strength grade is not high mostly.For the materials demand of oil, gas well, adopt multiple titanium alloy (as table 2) to carry out development work abroad, the impelling strength of trial-production alloy has no report.

Table 2 is the oil well titanium alloy trade mark of development both at home and abroad

Nominal composition	Minimum yield strength Rp0.2/MPa
		Industrially pure titanium	140
Industrially pure titanium	275
		Ti-0.3Mo-0.8Ni	345
Ti-3Al-2.5V	485
		Ti-3Al-2.5V-0.05Pd	485
Ti-3Al-2.5V-0.1Ru	485
		Ti-6Al-4V ELI	760
Ti-6Al-4V-0.05Pd	828
		Ti-6Al-4V-0.1Ru	760

Domestic to oil, gas well not yet carries out by titanium alloy development work.It is reported that domestic unit copies the foreign technology route at TC4(Ti-6Al-4V) on the basis of alloy, by adding trace element, improve its impact property, to meet technical requirements, but its product has no report.Therefore, develop titanium alloy that intensity, impelling strength performance meets Its Relevant Technology Standards meeting domestic oil, gas well novel material demand is very necessary.

High strength, high impact toughness titanium alloy that patent of the present invention proposes, take oil, gas well is target with the materials demand of P110 grade of steel, in many-sides such as material composition, Technological adaptabilities, all with existing high strength, high-tenacity titanium alloy, obvious difference is arranged.

Aspect material composition, the high strength of domestic development, high-tenacity titanium alloy all design for the aviation demand, be а+beta type titanium alloy, high strength, high-tenacity titanium alloy Ti-6Al-2Sn-2Zr-2Cr-Mo-Si as domestic certain unit development, this alloy intensity after solid solution aging can reach 1100MPa, fracture toughness KIC can reach 84MPa.m1/2, the impelling strength index of this alloy has no report, press corresponding relation, impelling strength should be in the 45J left and right, impact can meet the index of correlation requirement, but yield strength is too high.External development oil, gas well are basis with titanium alloy mainly with ripe high-strength alloy (Ti-6Al-4V is maximum), by adding trace element, improve its impact property.Such alloy is а+beta type titanium alloy, has higher intensity and good processing performance, but the raising difficulty of its impact property is larger.This patent, aspect alloy designs, by the reasonably combined use of the alloying elements such as Al, Mo, Zr, Nb, is designed nearly а type alloy, guarantees that alloy has good intensity, impelling strength.

Aspect Technological adaptability, the high strength of domestic development, high-tenacity titanium alloy need to process through solid solution aging more, and this technique length consuming time, process costs are high, thus cause product cost tool height not under, also be difficult to realize large-scale industrial production, be unfavorable for applying.The alloy of patent of the present invention has good Technological adaptability, and after conventional forging and the tubing technological process of production, the intensity of this alloy, impact property meet the P110 grade of steel material property technical requirements of API 5CT.

At present, the new alloy of patent of the present invention has passed through the examination of simulated condition condition, at H ₂s, CO ₂and Cl ^-1under the hyperbaric environment coexisted, there is good corrosion resistance nature.

Summary of the invention

For the effective titanium alloy demand of oil, the gas well of P110 grade of steel, design and develop a kind of room temperature tensile strength Rm >=862MPa, yield strength Rp0.2 >=760MPa, Akv >=47J, anti-H2S, the titanium alloy that the CO2 corrosive nature is good, for titanium alloy oil well pipe product provides materials for support.

In order to realize described goal of the invention, the present invention adopts following technical scheme:

A kind of oil, gas well high strength high impact toughness titanium alloy, its chemical component weight percentage range is: Al, 4.0-9.0%, Mo, 0.5-5.0%, Nb, 1-5%, Zr, 1-5%, surplus is Ti.

Titanium alloy of the present invention is nearly alpha titanium alloy.

Titanium alloy room-temperature mechanical property index of the present invention is Rm >=860MPa, Rp0.2 >=760MPa, A >=13%, AKV >=47J.

A kind of oil, the gas well preparation method of high strength high impact toughness titanium alloy, concrete operation step is as follows:

(1) by component concentration, Al, Mo, Nb, Zr, Ti are carried out to batch mixing, mix;

(2) utilize pressing machine that the raw material mixed is pressed into to electric shock baton;

(3) electrode is put into to vacuum consumable electrode arc furnace and carried out melting once, obtain ingot one time;

(4) ingot is carried out to secondary smelting in vacuum consumable electrode arc furnace as consumable electrode, obtain ingot casting;

After (5) twice melting, 1150 ℃ of coggings are forged, and 970 ℃ ~ 1020 ℃ change forging, obtain finished product after annealing.

Owing to having adopted technique scheme, the present invention has following beneficial effect: the present invention proposes to take Ti as matrix, Al, Mo, Nb, Zr are main alloy element, wherein the Al element is main strengthening element, significantly put forward heavy alloyed tensile strength and creep rupture strength, Al content is 7% when following, and alloy still can keep good plasticity and toughness and thermostability; Mo, Nb element are beta stable element, when improving Alloy At Room Temperature, high-temperature behavior, guarantee the good process plastic of alloy, and two kinds of elements add than the raising of only adding a kind of element and more be conducive to over-all properties simultaneously; Zr is neutral element, can put forward the thermostability that heavy alloyed heat resistance does not affect alloy simultaneously, and crystal grain thinning.

The titanium alloy of patent of the present invention can solve existing P110 steel grade oil, the anti-H of gas well tube material well ₂s, CO ₂the not enough problem of corrosive nature, can realize 40% loss of weight simultaneously, greatly reduces rig power.Oil, Natural gas extraction ability to China will have larger lifting.

This alloy has good cold/hot shaped performance, can very successfully prepare titanium alloy pipe.This alloy pipe has the characteristic of high strength, high tenacity, meets the technical requirements of P110 grade of steel.

This alloy is having application prospect preferably aspect the oil well pipe of P110 grade of steel and drill pipe of oil well field.Simultaneously, can be applied to ocean platform, petrochemical equipment and the field of equipment loss of weight or anti-corrosion requirement is arranged.

Embodiment

In conjunction with specific embodiments the present invention is illustrated, but be not limited to this specific embodiment, the present invention also has various changes and modifications without departing from the spirit and scope of the present invention, and these changes and improvements all belong to protection scope of the present invention.

Embodiment mono-:

Fine aluminium beans by 9%, 3% Nb piece, 0.5% Mo piece, 1% pure sponge Zr, industrial one-level sponge Ti are smelted into alloy cast ingot twice by batch mixing, electrode pressing rod, vacuum consumable.998 ℃ of alloy phase heights, 1150 ℃ of coggings are forged, and 970 ℃ change forging for Φ 150 bars, and the bar ambient temperature mechanical properties after annealing is in Table 3.Adopt the simulation oil well working condition, adopt the bar test piece to carry out the corrosive nature examination, test conditions and experimental performance are in Table 4.

Embodiment bis-:

Fine aluminium beans by 5.5%, 1% Nb piece, 5% Mo piece, 3% pure sponge Zr industry one-level sponge Ti are smelted into alloy cast ingot twice by batch mixing, electrode pressing rod, vacuum consumable.1005 ℃ of alloy phase heights, 1150 ℃ of coggings are forged, and 980 ℃ change forging for the 150mm bar, prepare 89 * 9 tubing through overmolding, and the tubing ambient temperature mechanical properties after annealing is in Table 3.Adopt the simulation oil well working condition, adopt the tubing test piece to carry out the corrosive nature examination, test conditions and experimental performance are in Table 4.

Embodiment tri-:

Fine aluminium beans by 4%, 5% Nb piece, 3.5% Mo piece, 5% pure sponge Zr, industrial one-level sponge Ti are smelted into alloy cast ingot twice by batch mixing, electrode pressing rod, vacuum consumable.993 ℃ of alloy phase heights, 1150 ℃ of coggings are forged, and 1020 ℃ change forging for thickness 90mm slab, roll out 14mm sheet material, and the sheet material ambient temperature mechanical properties after annealing is in Table 3.Adopt the simulation oil well working condition, adopt the sheet material test piece to carry out the corrosive nature examination, test conditions and experimental performance are in Table 4.

The ambient temperature mechanical properties of three kinds of embodiment of table 3

Table 4 simulated condition evaluation test condition and result

Part not in the detailed description of the invention is prior art.

Claims (4)

1. an oil, high strength high impact toughness titanium alloy for gas well, it is characterized in that: its chemical component weight percentage range is: Al, 4.0-9.0%, Mo, 0.5-5.0%, Nb, 1-5%, Zr, 1-5%, surplus is Ti.

2. high strength high impact toughness titanium alloy for oil as claimed in claim 1, gas well, it is characterized in that: described titanium alloy is nearly alpha titanium alloy.

3. high strength high impact toughness titanium alloy for oil as claimed in claim 1, gas well, it is characterized in that: described titanium alloy room-temperature mechanical property index is R _m>=860MPa, R _p0.2>=760MPa, A>=13%, A _kV>=47J.

4. the preparation method of high strength high impact toughness titanium alloy for an oil as claimed in claim 1, gas well is characterized in that:

(1) by component concentration, Al, Mo, Nb, Zr, Ti are carried out to batch mixing, mix;

(2) utilize pressing machine that the raw material mixed is pressed into to electrode bar;

(3) electrode is put into to vacuum consumable electrode arc furnace and carried out melting once, obtain ingot one time;

(4) ingot is carried out to secondary smelting in vacuum consumable electrode arc furnace as consumable electrode, obtain ingot casting;

After (5) twice melting, 1150 ℃ of coggings are forged, and 970 ℃ ~ 1020 ℃ change forging, obtain finished product after annealing.