CN102312163A - Steel for mandrel pipe mill mandril and preparation technology thereof - Google Patents

Abstract

The invention relates to steel for a mandrel pipe mill mandril and a preparation technology thereof. An alloy component of the steel comprises: by mass, 0.20 to 0.40% of C, less than or equal to 0.6% of Si, 0.7 to 1.3% of Mn, 2.8 to 3.8% of Cr, 0.30 to 0.60% of Mo, 0.20 to 0.50% of V, 0.01 to 0.07% of Nb and the balance Fe and unavoidable impurity elements, wherein the unavoidable impurity elements comprise less than or equal to 0.015% of S, less than or equal to 0.015% of P and less than or equal to 30 ppm of O. The steel is subjected to electro-smelting, electroslag remelting, annealing, forging and annealing and then has good machining properties. The steel is subjected to heat treatment of quenching and high-temperature tempering and then has good high temperature intensity and hardness and a great thermal conductivity coefficient, wherein the thermal conductivity coefficient is great than or equal to 34W/(M.K) (20 to 400 DEG C) and is 40% higher than a thermal conductivity coefficient of steel H13.

Description

Mandrel mill is with steel and preparation technology thereof

Technical field

The present invention relates to a kind of novel high heat conduction mandrel mill material.The steel that uses in the market is high-alloy hot work die steel such as H13 and H11, and the steel that the present invention relates to is a kind of middle-low alloy steel.Be characterized in having the higher capacity of heat transmission, can obtain lower surface temperature, increase thermal fatigue resistance possessing general plug for example on the hardness that had of H13 steel, the flexible basis.

Background technology

MPM tandem rolling tube machine in first big mouth of sheath footpath was constructed and put into operation in Italian Da Er exposed penstock factory in 1978 in the world.The appearance of MPM to a brand-new level, owing to the many advantage of MPM at aspects such as technology, quality product and production efficiencys, just obtains rapid promotion and application once coming out with the continuously rolling process technical development in the whole world.Especially since the eighties in last century, received the influence in great demand of oil industry, impelled the develop rapidly of MPM technology oil well pipe.

China introduces many MPM production lines in recent years, the basic dependence on import of its main consumptive material plug, and the major diameter plug is with high content of technology, manufacture difficulty is big, has only few countries such as France, Italy, Germany to have throughput at present.The present plug manufacturing capacity of China with abroad have a long way to go, major diameter plug especially, the plug manufacturing of size more than Φ 280mm specification is still blank; Whole dependence on import; The import plug not only costs an arm and a leg, and delivery cycle is long, and imbalance between supply and demand is very outstanding.

There are two aspects in heavy caliber mandrel mill manufacturing technology difficult point: the one, and the manufacturing technology and the equipment of shortage high quality major diameter mandril blank; The 2nd, lack the precision control of the heat treated organizational controls of plug, long pole mechanical workout and the correlation technique and the equipment of plating hard chromium on surface.

At first, the manufacturing of major diameter mandril blank needs high-quality large-scale hot-work die steel ingot, because dimensional effect, steel ingot is big more, and its metallurgical quality, carbide, segregation control difficulty will increase substantially.The manufacturing of high-quality mandril blank not only needs advanced metallurgical quality opertaing device such as vacuum refinement, esr as pacing items, also needs state-of-the-art technology and equipments such as high temperature homogeneous, multiway forging, microstructure ultra-fining treatment to guarantee.Secondly, according to external experience, need for the large mould product made from steel of elongated type of this type of plug specialty band dual operation machine large-tonnage soon the forging machine produce, domestic almost do not have this type professional equipment.And; Only grasp from large-scale steel ingot metallurgical quality and organizational controls methodically, forge back organizational controls, mandril blank organizational controls; Quenching heat treatment, the complete microtexture control techniques of tempering heat treatment series to plug; Just can give full play to the highly malleablized effect of die steel interalloy element, produce and have the major diameter plug that excellent high intensity has the excellent high H.T. again concurrently, satisfy the actual demand of using.

Summary of the invention

Goal of the invention: the present invention provide a kind of novel low-cost tandem rolling tube machine with high heat conduction plug with steel and preparation technology thereof.

1. alloying constituent: it is (mass percent) that the hollow plug of this novel tandem rolling tube machine uses the alloying constituent of steel:

C 0.20~0.40%

Si ≤0.6%

Mn 0.7-1.3%

Cr 2.8~3.8?%

Mo 0.30-0.60%

V 0.20~0.50%

Nb 0.01~0.07%

The Fe surplus

The unavoidable impurities element, S in the impurity element :≤0.03%; P :≤0.03%; O :≤30ppm.

2. preparation technology and thermal treatment process:

A. melting: alloy carries out electrosmelting after pressing the mentioned component design, and the admixtion in the above-mentioned prescription is positioned in the electric furnace, carries out melting in the temperature more than 1500 ℃, cast φ 200mm-φ 800mm electrode bar;

B. esr: the content that can reduce gas and inclusion behind the esr; And obtain composition evenly, dense structure, steel ingot that quality is high; Change slag voltage 56-62V; Electric current 3000-5000A, electric system voltage 57-59V, electric current 11000-12000A, the voltage 57-59V that binds, packing ratio is 0.8;

C. annealing: in 700 ℃ the insulation 8 hours after furnace cooling;

D. forge: steel ingot is heated to 1200～1230 ℃, carries out multiway forging, 1000 ℃ of final forging temperatures, and forging ratio is greater than 6;

E. forging rear annealing: in 700 ℃ of annealing 8 hours, furnace cooling;

F. thermal treatment: 900-940 ℃ quenching, 600-630 ℃ of tempering two hours;

The steel that uses in the market is high-alloy hot work die steel such as H13 and H11, and the steel that the present invention relates to is a kind of middle-low alloy steel.Be characterized in having the higher capacity of heat transmission, can obtain lower surface temperature, increase the thermal fatigue resistance of plug possessing general plug for example on the hardness that had of H13 steel, the flexible basis.

Description of drawings

The thermal conductivity ratio that Fig. 1 invents steel and H13 steel.

Embodiment

Below in conjunction with embodiment the present invention is elaborated:

Embodiment one:

Present embodiment has been produced a kind of steel, and its concrete composition is following:

C 0.30%， Si 0.35%，

Mn 1.0%， Cr 3.2%，

Mo 0.5%， V 0.35%，

Nb 0.04% P ?<0.015%，

S <0.015%， O ≤30ppm

The Fe surplus

Concrete steps are following:

A. melting: alloy carries out electrosmelting after pressing the mentioned component design, and the admixtion in the above-mentioned prescription is positioned in the electric furnace, carries out melting in the temperature more than 1500 ℃, cast φ 450mm electrode bar;

B. esr: the content that can reduce gas and inclusion behind the esr; And obtain composition evenly, dense structure, steel ingot that quality is high, change slag voltage 58V, electric current 3000-5000A, electric system voltage 57V; Electric current 11500A, the voltage 58V that binds, packing ratio is 0.8;

C. annealing: in 700 ℃ the insulation 8 hours after furnace cooling;

D. forge: steel ingot is heated to 1200～1230 ℃, carries out multiway forging, 1000 ℃ of final forging temperatures, and forging ratio is greater than 6;

E. forging rear annealing: in 700 ℃ of annealing 8 hours, furnace cooling;

F. thermal treatment: 920 ℃ of quenchings, 620 ℃ of tempering two hours;

G. actual thermal conductivity that must this production steel is: 50 ℃: 35W/mK, 200 ℃: 36.3 W/mK; 400 ℃: 37.8 W/mK.

Claims (2)

1. mandrel mill is used steel, it is characterized in that the composition of this steel is counted with the quality percentage composition: C:0.20-0.40%; Si :≤0.6%; Mn:0.7-1.3%; Cr:2.8-3.8%; Mo:0.30-0.60%; V:0.20-0.50%; Nb:0.01-0.07%; All the other are Fe and unavoidable impurities element, S in the impurity element :≤0.03%; P :≤0.03%; O :≤30ppm.

2. mandrel mill is characterized in that with the preparation technology of steel this preparation technology adopts following steps to carry out:

A. melting: with being positioned in the electric furnace after the prescription batching of alloy by claim 1, carry out melting, cast φ 200mm-φ 800mm electrode bar in the temperature more than 1500 ℃;

B. esr: the parameter of esr is: change slag voltage 56-62V, and electric current 3000-5000A, electric system voltage 57-59V, electric current 11000-12000A, the voltage 57-59V that binds, packing ratio is 0.8;

C. annealing: in 700 ℃ the insulation 8 hours after furnace cooling;

D. forge: steel ingot is heated to 1200～1230 ℃, carries out multiway forging, 1000 ℃ of final forging temperatures, and forging ratio is greater than 6;

E. forging rear annealing: in 700 ℃ of annealing 8 hours, furnace cooling;

F. thermal treatment: 900-940 ℃ quenching, 600-630 ℃ of tempering two hours.

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