CN106077579A

CN106077579A - A kind of pouring procedure of 600MW boundary over zero Steam Turbine's Main Vaper Valve sand mold steel-casting

Info

Publication number: CN106077579A
Application number: CN201610603506.0A
Authority: CN
Inventors: 张辉; 陆怡
Original assignee: SANXIN HEAVY INDUSTRY MACHINERY Co Ltd
Current assignee: SANXIN HEAVY INDUSTRY MACHINERY Co Ltd
Priority date: 2016-07-27
Filing date: 2016-07-27
Publication date: 2016-11-09

Abstract

The invention discloses the pouring procedure of a kind of 600MW boundary over zero Steam Turbine's Main Vaper Valve sand mold steel-casting, belong to machine casting field.The present invention extracts the air in sand mold and die cavity, the most same argon before cast starts, and provides argon stream protective cover for molten steel in casting process.The flaw detection grade of gained foundry goods is 0 grade, and mending of iron castings amount significantly drops to 0.5% from the 3% of foundry goods net weight, has both reduced mending of iron castings amount, meets and day by day improves steel-casting prescription, increases again Foundry Works's economic benefit.

Description

A kind of pouring procedure of 600MW boundary over zero Steam Turbine's Main Vaper Valve sand mold steel-casting

Technical field

The present invention relates to the pouring procedure of a kind of 600MW boundary over zero Steam Turbine's Main Vaper Valve sand mold steel-casting, belong to machinery casting Make field.

Background technology

Along with social life and the development of science and technology, people are more and more higher to steel-casting prescription.With regard to steam turbine row For industry, along with steam turbine work efficiency steps up, performance and prescription to steam turbine steel-casting are more and more higher, existing The alloy contents such as Cr, Ni, the Mo at these type of foundry goods a lot of step up, and flaw detection grade is also stepping up, some foundry goods local Even entirety is all 0 grade of flaw detection requirement.

Tradition pouring procedure is in casting process, and molten steel easily reacts with the oxygen in air and produces secondary oxidation and be mingled with Thing.And, in molten steel, alloy content is the highest, is more easily generated secondary oxidation field trash.Additionally, when molten steel viscosity increases with alloy content Adding and increase, field trash is difficult to float and removes.So foundry goods field trash of cast is the most serious, it is difficult to meets flaw detection quality and wants Ask, bring substantial amounts of soldering to work, which results in the problems such as higher, the time delay at date of delivery of casting cost, have a strong impact on Foundry Works Economic benefit.

Summary of the invention

It is desirable to provide the pouring procedure of a kind of 600MW boundary over zero Steam Turbine's Main Vaper Valve sand mold steel-casting.

Described method is bottom pouring type pouring, mainly comprises the steps that

(1) within first 20 minutes, use plastic film seal casting mold in cast, at rising head, extract the sky in die cavity, sand mold with vacuum pump Gas, and make casting mold vacuum degree be maintained at 0.05MPa, pressurize 10 minutes；

(2 from casting mold cast gate applying argon gas 10 minutes, and during argon filling, argon pressure is gradually increased to 0.2～0.3MPa, makes casting Being full of argon in type and die cavity, argon pressure reaches 0.2～0.3MPa, and pressurize starts cast for about 10 minutes；

(3) being arranged around argon shield circle at the ladle bottom mouth of a river during cast, described argon shield circle is that an internal diameter is big In the steel ring of mouth of a river diameter, steel ring bottom surface offers multiple passage, steel ring side and argon pipeline communication；Cast start time to Persistently leading to argon in steel ring until cast terminates, venting pressure is set to 0.15～0.2MPa, the argon ventilation by steel ring bottom surface Hole is flowed out and flows to identical with molten steel.

In one embodiment of the invention, the described ladle bottom mouth of a river and the distance about 2m of die cavity water filling port.

In one embodiment of the invention, described steel ring is external diameter 308mm, the steel ring of internal diameter 300mm, outgassing direction One side be evenly distributed with the passage of 28 diameter 3mm.

In one embodiment of the invention, the material of steel-casting is ZG1Cr10MoWVNbN heat resisting steel.

The pouring procedure of the present invention, it is ensured that at 600MW boundary over zero Steam Turbine's Main Vaper Valve sand mold steel-casting in casting process Secondary oxidation slag inclusion generation amount is greatly decreased.The flaw detection grade of gained foundry goods is 0 grade, and mending of iron castings amount is from the 3% of foundry goods net weight Significantly drop to 0.5%, both reduced mending of iron castings amount, meet and day by day improve steel-casting prescription, increase again Foundry Works Economic benefit.

Accompanying drawing explanation

Fig. 1 foundry goods flaw detection class requirement schematic diagram；

The schematic diagram of Fig. 2 routine casting casting；

The schematic diagram of Fig. 3 embodiment 2 casting and pouring method；

Fig. 4 steel ring schematic diagram；

Before Fig. 5 embodiment 3 casting and pouring, evacuation leads to the schematic diagram of argon.

Detailed description of the invention

The acceptance condition of table 1 foundry goods individual defect

Flaw detection grade	NONLINEAR DEFECT maximum area (cm<sup>2</sup>)	Defective locations
			0	0	Whole wall thickness
1	6.5	Whole wall thickness

Note: NONLINEAR DEFECT maximum area is probe migration area on cast(ing) surface.

The acceptance condition of table 2 foundry goods close defect

Note 1: do not consider middle wall thickness 1/3 or outer inwall 1/3 in the position of wall thickness；

Note 2: each measures its area more than the Application of defect half-wave method of 12.7mm reference line, wave height 6.4mm is edge, Connect center probe line, when cannot measure defect area, each should be by 0.97cm more than the defect of 12.7mm reference line²Area Defect adds up (be φ 6.4mm hole area and be multiplied by the defect reflection loss coefficient of 3 times)；

Note 3: cumulative intensive labelling area must be in dispersed and distributed, and its distributed areas are at least 232cm², otherwise, should mend Weldering is to meet credit rating requirement.

Embodiment 1

The net weight 13.5 tons of 600MW boundary over zero steam turbine upper-part stop valve, spray weighs 20 tons, pour steel amount 40 Ton, castings material is ZG1Cr10MoWVNbN heat resisting steel (alloy content is about 14%), and foundry goods flaw detection class requirement is shown in Fig. 1, In Fig. 1, in dotted line frame, flaw detection class requirement is 0 grade, and remaining is 1 grade.The foundry goods high to this large-scale amount containing alloy, if casting The process of making can not reduce the generation of oxide inclusion as far as possible, it will produces substantial amounts of soldering burden.

Routine casting casting as shown in Figure 2, directly flows into foundry goods type via geat, running channel by molten steel from ladle Chamber, the foundry goods secondary oxidation slag inclusion obtained is more, and ultrasonic examination, it has also been found that the slag inclusion class defect exceeded standard is more, digs soldering after lacking Amount is big, soldering amount averaged occupation foundry goods net weight 3%.And the welding rod used by this kind of foundry goods needs import, welding rod price per ton 170,000, often Foundry goods bare electrode expense the most up to more than 68850 yuan, wastes time and energy, has a strong impact on Foundry Works's economic benefit.

Embodiment 2

Target foundry goods in embodiment 1 changes into using method cast shown in Fig. 3, places below ladle nozzle during cast One internal diameter 300mm, the steel ring of external diameter 308mm, steel ring bottom is drilled with the circular hole of 28 diameter 3mm as argon blow vent, Fig. 4 For steel ring upward view.During cast, steel ring is passed through pressure is 0.2～0.3MPa argon, by the shape between the mouth of a river and cast gate of argon in steel ring Gas shield cover, isolation air is become to contact with steel flow.The foundry goods slag inclusion class defect that this method pours into a mould out has reduced, soldering amount Averagely at foundry goods net weight 2.5%, can reduce 0.5%, every foundry goods welding rod expense is 57375 yuan, reduces by 11475 yuan.

Embodiment 3

Such as Fig. 5, at casting pouring first 20 minutes, use plastic film seal casting mold, with in vacuum pump extraction sand mold and die cavity Air, casting mold vacuum degree is maintained at 0.05MPa, pressurize 10 minutes, is then shut off valve on vacuum pipe, progressively opens and take tunger tube Valve on road, applying argon gas in casting mold, argon pressure incrementally increases 0.2～0.3MPa, and pressurize starts cast for about 10 minutes. When cast, below ladle nozzle, method as shown in embodiment 2 places a steel ring leading to argon, and steel ring is continually fed into pressure and is The argon of 0.2～0.3MPa is until cast terminates.Molten steel enters fast cooling after casting mold, and oxidizing reaction rate declines.Use this The mending of iron castings amount average out to foundry goods net weight 0.5% that embodiment method pours into a mould out, every foundry goods welding rod expense is 11475 yuan, Reduce by 57375 yuan than the casting of embodiment 1, reduce by 45900 yuan than the casting of embodiment 2, Foundry Works warp can be greatly improved Ji benefit.

Embodiment 4

With reference to the pouring procedure of embodiment 3, difference is, extracts the air in die cavity with vacuum pump, and does not extract sand mold In air, casting mold vacuum degree is maintained at 0.03MPa, pressurize 10 minutes；Subsequent step is identical with the subsequent step of embodiment 3. Final cast mending of iron castings amount average out to foundry goods net weight 1.2% out, every foundry goods welding rod expense is 27540 yuan, than enforcement The casting of example 1 reduces by 41310 yuan, reduces by 29835 yuan than the casting of embodiment 2.

Embodiment 5

With reference to the pouring procedure of embodiment 3, difference is, before the air in vacuum pump extraction sand mold and die cavity, no Using plastic film seal casting mold, with the air in vacuum pump extraction sand mold and die cavity, casting mold vacuum degree is maintained at 0.05MPa, pressurize 10 minutes, it is then shut off valve on vacuum pipe, progressively opens and take valve on argon pipeline, applying argon gas in casting mold, argon pressure Incrementally increase 0.2～0.3MPa, pressurize about 10 minutes, allow and die cavity, sand mold are full of argon, artificially Casting mold manufacturing is become lazy Property atmosphere.When cast, below ladle nozzle, as shown in embodiment 2, argon steel ring is led in method placement one.Molten steel is whole After casting process, and cast, molten steel encloses all in noble gas argon atmospher in a period of time, it is to avoid molten steel and air contact. Molten steel enters fast cooling after casting mold, and oxidizing reaction rate declines.Use the mending of iron castings amount that the present embodiment method pours into a mould out Average out to foundry goods net weight 1.8%, every foundry goods welding rod expense is 41310 yuan, reduces by 27540 yuan than the casting of embodiment 1, than The casting of embodiment 2 reduces by 16065 yuan.

Embodiment 6

On the basis of embodiment 2, the position corresponding with ladle nozzle at casting mold water filling port disposes one further Same specification, argon passage are towards the steel ring contrary with molten steel injection direction.The soldering amount of the foundry goods that this method pours into a mould out Average at foundry goods net weight 2.8%, only reduce 0.2%.Argon steel ring is set simultaneously at ladle nozzle and casting mold water filling port, not The soldering amount of foundry goods can be reduced further, compare and declined only with an effect during steel ring, it may be possible to air-flow is disorderly Random reason.

Although the present invention is open the most as above with preferred embodiment, but it is not limited to the present invention, any is familiar with this skill The people of art, without departing from the spirit and scope of the present invention, can do various changes and modification, therefore the protection model of the present invention Enclosing should be with being as the criterion that claims are defined.

Claims

1. the pouring procedure of 600MW boundary over a zero Steam Turbine's Main Vaper Valve sand mold steel-casting, it is characterised in that described method is the end Note formula is poured into a mould, and mainly comprises the steps that

(1) within first 20 minutes, use plastic film seal casting mold in cast, at rising head, extract the air in die cavity, sand mold with vacuum pump, And make casting mold vacuum degree be maintained at 0.05MPa, pressurize 10 minutes；

(2 from casting mold cast gate applying argon gas 10 minutes, and during argon filling, argon pressure is gradually increased to 0.2～0.3MPa, make casting mold and Being full of argon in die cavity, argon pressure reaches 0.2～0.3MPa, and pressurize starts cast for about 10 minutes；

(3) being arranged around argon shield circle during cast at the ladle bottom mouth of a river, described argon shield circle is that an internal diameter is more than water The steel ring of mouth diameter, steel ring bottom surface offers multiple passage, steel ring side and argon pipeline communication；To steel ring when cast starts In persistently lead to argon until cast terminates, venting pressure is set to 0.15～0.2MPa, and argon is by the passage stream of steel ring bottom surface Go out and flow to identical with molten steel.

Method the most according to claim 1, it is characterised in that the distance of the described ladle bottom mouth of a river and die cavity water filling port is about 2m。

Method the most according to claim 1, it is characterised in that described steel ring is external diameter 308mm, the steel ring of internal diameter 300mm, The one side of outgassing direction is evenly distributed with the passage of 28 diameter 3mm.

Method the most according to claim 1, it is characterised in that the material of steel-casting is ZG1Cr10MoWVNbN heat resisting steel.