CN102337449A - GRTCr high-toughness high-heat conduction cooling wall and production method thereof - Google Patents

Abstract

The invention relates to a GRTCr heatproof iron casting used for an air heating furnace of an iron making furnace and a production method thereof. By using an improved RTCr formula and a smelting breeding technology and matching with a heatproof iron casting produced by using a novel lost foam casting technology, the tensile intensity is larger than or equal to 450MPa and the extension rate is larger than or equal to 5%. The production method comprises the following steps of: processing a foam model (lost foam model) according to design requirements of a product; coating special paint, drying and boxing for standby; adding various alloy elements to a medium-frequency inductive furnace for smelting according to a set formula sequence; casting the elements into a model box at negative pressure after the elements are qualified through inoculation treatment so as to obtain a casting with consistent shape and size with the lost foam model; cooling, and opening the box; carrying out surface processing; mechanical processing and quality inspecting to obtain the GRTCr heatproof iron casting used for the air heating furnace of the air making furnace according to the design requirements. The mass percent of the alloy elements is as follows: 3.0%-3.8% of C,1.5-2.5% of Si,10% of Mn, 0.5-1.0% of Cr, smaller than or equal to 0.20% of P, smaller than or equal to 0.12 of S and the balance of Fe.

Description

High tough high heat conduction cooling stave of GRTCr and working method thereof

Technical field

The present invention relates to high tough high heat conduction heat resisting iron cooling stave of GRTCr and working method thereof, belong to iron-smelting blast furnace and high temperature kiln cooling apparatus field.

Background technology

For a long time, cast-iron cooling wall is to use maximum, the cheapest a kind of cooling apparatus of cost in the blast furnace cooling stave always.But because the limitation of the mechanical property of common grey iron HT200 and common heat resisting iron RTCr self, its tensile strength is merely σ _b>=200MPa, unit elongation δ ₅Be 0, cause cooling stave low work-ing life, influenced the blast furnace ordinary production; Existing ME reduces water-cooled tube toughness in order to prevent the carburizing in casting process of cooling stave water pipe; At water-cooled tube outside surface brushing one deck pottery masking paste; When forming coating thermal boundary, form the air gap thermal boundary of 0.1-0.3mm between cooling stave body and the water-cooled tube; Existing casting technique is difficult to solve water-cooled tube the secondary oxidation problem at high temperature takes place, and has reduced the net sectional area of water pipe, has shortened work-ing life.

Summary of the invention

The purpose of this invention is to provide the high tough high heat conduction heat resisting iron cooling stave of a kind of GRTCr, the tensile strength sigma of its body _b>=450MPa, unit elongation δ ₅>=5%; Water-cooled tube and cooling stave body do not fuse, its gap≤0.05mm; Sampling analysis in the steel tube surface 1mm depth range, average carbon increasing amount≤0.02% of matrix relatively; The steel pipe inner wall smooth, no secondary oxidation phenomenon.

The objective of the invention is to realize like this: GRTCr is high, and tough high heat conduction heat resisting iron cooling stave adopts intermediate frequency furnace melting, lost foam casting technology to produce: metallic substance is used the medium-frequency induction furnace melting; Manganese adds in the molten clear back of molten iron; Smelting temperature 1400-1550 ℃; The melting later stage adds ferrosilicon, ferrochrome, and tapping temperature is controlled at 1400-1460 ℃, teeming temperature 1300-1380 ℃; Breed with the strong nucleating agent of imitating when coming out of the stove; The alloying element mass percent of the high tough high heat conduction heat resisting iron cooling stave of GRTCr is: C:2.5-3.8, Si:1.5-3.0, Mn :≤1.0, Cr:0.3-3.5, P≤0.20, S≤0.12, surplus is Fe.By bend the fixed water-cooled tube of the lateral of publishing picture with weldless steel tube, brush special anti-carburization coating; Process bubbles model by the cooling stave design requirements, insert the water-cooled tube of handling well in the bubbles model, utilize special coating brushing, drying, vanning; Add melting in the medium-frequency induction furnace to metallic substance, after inoculation is qualified, vacuum-assist pouring.In the casting process, under the effect of high temperature liquid iron, in the 1mm depth range of water-cooled tube surface, average carbon increasing amount≤0.02% of matrix has relatively been eliminated the secondary oxidation phenomenon of water-cooled tube internal surface simultaneously.Molten iron replaces bubbles model, obtains the cooling stave product with the mould shapes consistent size.Now combine accompanying drawing and embodiment that the present invention is described further.

Description of drawings

This Figure of description is the high tough high heat conduction heat resisting iron cooling stave working method process flow sheet of GRTCr; Arrow is represented operational path among the figure, square frame letter representation raw and auxiliary material, product: A steel pipe, B polystyrene foam, C masking paste, D lost foam paint, E molding sand, F sandbox, G molding box, Fe raw metal, Si silicon, Mn manganese, Cr chromium, YJ nucleating agent, CP product; Oval numeral process: 1 water-cooled tube simmers that system, 2 white molded works, 3 water-cooled tube brushing masking pastes, the assembling of 4 models, brushing lost foam paint, drying, 5 mold setting, 6 meltings, 7 are come out of the stove, 8 bred, 9 cast, 10 are unpacked, 11 clear up, 12 lead to that balls are suppressed, 13 quality tests, 14 vacuumize

Specific embodiments

Embodiment

Selecting material for use is the weldless steel tube (A) of straight carbon steel, wall thickness 4-12mm, bends water-cooled tube, accomplishes operation 1 water-cooled tube and makes; With masking paste B the water-cooled tube of making is carried out surface treatment, form anti-carburization coating, accomplish operation 3 water-cooled tube surface treatments; Utilize polystyrene foam B to process the cooling stave model, accomplish the Modelling of operation 2; The water-cooled tube planting model of finishing dealing with, brushing lost foam paint D accomplishes the assembling of operation 4 models, brushing disappearance mould tailor-(made) coating, model drying after dry; Dry good model is packed among the sandbox F; The assembling gating system adds molding sand E ram-jolt, and it is subsequent use to obtain molding box G; Melting operation 6 is carried out in medium-frequency induction furnace: add melting in the stove to raw metal Fe; Molten clear back adds chromium Cr, and smelting temperature is controlled at 1400-1520 ℃, and the melting later stage adds manganese Mn, silicon Si; Getting into operation 7 comes out of the stove; Tapping temperature is controlled at 1400-1460 ℃; Breed with the strong nucleating agent YJ of imitating when coming out of the stove; Operation 8 is bred in completion, and the mass percent of the high tough high heat conduction heat resisting iron cooling stave alloying element of control GRTCr is: C:2.5-3.8, Si:1.5-3.0, Mn :≤1.0, Cr:0.3-3.5, P≤0.20, S≤0.12, and surplus is Fe; Simultaneously, start the molding box vacuum system, implement the vacuum pumping of operation 14, carry out the pouring practice of operation 9: pouring condition is molding box pressure-0.02--0.09MPa, molten iron temperature 1380-1420 ℃; Cast is undertaken by " slow-fast-slow " method, and beginning is watered so that white mould gasifying gas is discharged slowly, prevents the molten metal splash, when the gating system porous plastics gasifies; After forming pouring channel, change over to soon immediately and water, make molten metal be full of sprue cup; Close sprue, make die cavity be in sealed state again, keep certain vacuum tightness; Float on the competent time in cast top or the scum riser for the residue after gasifying that is mingled in the molten metal is had at last, and make gas that the chance of whole discharge casting molds arranged, water by watering soon to change over to slowly; It is excessive in a large number to strictly avoid cutout and molten metal during cast, and the vacuum state with tamper-proof casting mold causes crush; Casting complete is after 8 to 10 hours cooling, through operation 10 unpack, operation 11 cleanings, operation 12 logical balls are suppressed, operation 13 quality tests, obtain the high tough high heat conduction heat resisting iron cooling stave of product G RTCr.Under as cast condition, the tensile strength sigma of the high tough high heat conduction heat resisting iron cooling stave body of GRTCr _b>=450MPa, unit elongation δ ₅>=5%.

Claims (3)

1. GRTCr heat resisting iron casting for hot-blast furnace comprises that blast funnace hot blast stove with fire grate, furnace stay, joist, spreader plate etc., is characterized in that: the tensile strength sigma of GRTCr heat resisting iron casting for hot-blast furnace _b>=450MPa, unit elongation δ ₅>=5%.

2. GRTCr heat resisting iron casting for hot-blast furnace according to claim 1; It is characterized in that: the mass percent of the high tough heat resisting iron spare alloying element of GRTCr is: C:2.5-3.8, Si:1.5-3.0, Mn :≤1.0, Cr:0.3-3.5, P≤0.20, S≤0.12, surplus is Fe.

3. the working method of GRTCr heat resisting iron casting for hot-blast furnace according to claim 1 is characterized in that: foundry goods adopts the lost foam casting technology to produce, and press the foundry goods drawing requirement and processes bubbles model; Utilize special coating brushing, drying, vanning; Add melting in the smelting furnace to alloy, under negative pressure, pour into a mould, obtain foundry goods with the mould shapes consistent size; Through cooling, unpack, operations such as cleaning, mechanical workout, assembling, the GRTCr heat resisting iron casting for hot-blast furnace product that obtains adhering to specification.

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