CN1040392A

CN1040392A - Smelting process of thin-walled high strength compound cast iron

Info

Publication number: CN1040392A
Application number: CN89105606A
Authority: CN
Inventors: 柯绿; 吴家立
Original assignee: Shanghai University of Engineering Science
Current assignee: Shanghai University of Engineering Science
Priority date: 1989-08-08
Filing date: 1989-08-08
Publication date: 1990-03-14

Abstract

The present invention is a kind of thin-wall high intensity synthetic cast iron smelting technique.It is with steel scrap, steel cuttings is a raw material, use no or little foundry iron, direct melting thin-wall high intensity cast iron, and the molten iron cast machined surface minimum wall thickness (MINI W.) that can reach 230MPa～270MPa with tensile strength is the thin-wall high intensity foundry goods of 3mm, do not use Mo, noble metals such as Cu, cost is low, applied range, but also can make full use of the iron and steel scrap smear metal.

Description

Smelting process of thin-walled high strength compound cast iron

The present invention is a kind of manufacturing process of thin-wall high intensity synthetic cast iron, relates to thin-wall high intensity Castiron Melting and steel scrap and utilizes the field.

Thin-wall high intensity synthetic cast iron and smelting technique are the science and technology that adapts to world today's high development, require ironcasting to study successful Castiron Melting product innovation and new technology to the needs of thin-walled property lightness development.The applicant once studied successful induction furnace synthetic cast iron in nineteen eighty-two, and the starting material that adopted are heavy scraps, and added a small amount of Gr, Mo, Cu alloying element.Can pour into a mould the foundry goods that the minimum process face is 6mm with the molten iron of 230～290MPa; And the processing minimum thickness be the foundry goods of 3mm can only be with the cast of the molten iron of tensile strength＜200MPa; Then can only pour into a mould as for general cupola furnace molten iron with the molten iron of tensile strength＜150MPa, otherwise can't the as cast condition machining.The alloy synthetic cast iron not only consumes alloying element, and price is higher, compares with general cast iron, and the cost decline scope is little, and the more important thing is, can not adapt to the requirement of thin-wall high intensity.

The objective of the invention is to propose a kind of above-mentioned shortcoming that overcomes, the molten iron cast machined surface minimum wall thickness (MINI W.) that can reach 230MPa～270MPa with tensile strength is the thin-wall high intensity foundry goods of 3mm, do not use noble metals such as Mo, Cu, the melting technology of lower-cost thin-wall high intensity synthetic cast iron.

The objective of the invention is to realize through the following steps:

At first, adopt following ratio of components batching:

Dead head 15%～20%

Steel cuttings 55%～85%

Iron filings 0%～25%

Heavy scrap 0%～10%

Add up to 100%

And:

Carburelant (graphite) 1.5%～4.5%

Increase silicea (75% ferrosilicon) 1.5%～3.5%

Nucleating agent 0.6%～1%

Gestagen (Mn+S) 0.2%～0.7%

(carburelant increases silicea, nucleating agent, gestagen all with the metal charge percentage calculation, but is not counted in the metal charge).

Melting technology:

1. add part metals material and carburelant and make it to form fast the molten bath, or retain molten iron and do the molten bath.

2. batch charging is repeatedly bred in the stove.

It is 1%～0.8% of total amount that 3 speeds of melting should be controlled at per minute fusing amount.

4. the power before the molten bath forms is 40%～60% of rated output, and power increases to 65%～80% behind the formation molten bath, makes molten iron temperature remain on 1200～1380 ℃, treats that whole furnace charges are molten clear, and power is brought up to 85%～90% and is warming up to 1450～1500 ℃ rapidly.

5. 30%～50% of nucleating agent before tapping a blast furnace, and adds in the stove.

Principle of the present invention is based on, make a large amount of pro-eutectic austenite of increase in the cast iron microstructure with steel scrap, strengthen pregnant effect with gestagen simultaneously, do not add Cr, Mo, alloying elements such as Cu, reaching the molten iron cast minimum process face that reaches 230MPa～270MPa with tensile strength is the foundry goods of 3mm, but and as cast condition machining.

The present invention has following characteristics:

1. the physicochemical property of products obtained therefrom is stable:

Mechanical property: its tensile strength can reach 230MPa～270MPa, hardness HB190～230, foundry goods minimum process face thickness 3mm, but as cast condition machining;

Chemical Composition:

CE 4.1%～4.25%

C 3.3%～3.5%

Si 2.4%～2.55%

Mn 0.6%～0.8%

P 0.07%～0.15%

S 0.07%～0.15%

2. the present invention is applied widely, can be used for compressor of air conditioner, general compressor, and water pump impeller, the internal combustion engine cylinders cylinder caps of automobile, tractor etc. are part in addition, and diesel engine ironcasting, cast iron valve etc. require the thin-wall high intensity ironcasting.

3 costs are low, and are good in economic efficiency.

4. can solve the utilization of iron and steel scrap smear metal.

Below by example, the invention will be further described:

Example 1. is with old material 9.92%

Steel cuttings 64.9%

Iron filings 15.23%

Heavy scrap 9.92%

And the graphite carburelant of metal charge weight 2.2%, 1.85% 75 ferrosilicon increase silicea, 0.89% nucleating agent, and 0.55% gestagen (Mn+S) is prepared burden.

Add part metals material and carburelant earlier and make it to form the molten bath, batch charging again, repeatedly breed in the stove, and carry out melting with 1% speed of per minute fusing total amount, power before the molten bath forms is 50% of rated output, forms behind the molten bath power and increases to 70% and make molten iron temperature remain on 1200～1380 ℃, treats that whole furnace charges are molten clear, power brings up to 90%, is warming up to 1450～1500 ℃ and before tapping a blast furnace 30% of nucleating agent is added in the stove.

The lining bar Chemical Composition of gained thin-wall high intensity synthetic cast iron:

C 3.30%

Mn 0.64%

Si 2.58%

P 0.048%

S 0.073%

CE 4.16%

The lining bar mechanical property

Amount of deflection 4.3～4.8% bending strength 487MPa～490MPa

Tensile strength 276MPa～279MPa hardness HB 204～217

Example 2. is with old material 9.92%

Steel cuttings 64.90%

Iron filings 15.23%

Heavy scrap 9.92%

And the graphite carburelant of metal charge weight 2.7%.2.3% 75% ferrosilicon increases silicea, 0.89% nucleating agent, and 0.6% gestagen (Mn+S) is prepared burden.

Operating procedure by example 1 is operated, and the Chemical Composition of gained thin-wall high intensity synthetic cast iron is:

C 3.35%

Mn 0.75%

Si 2.72%

P 0.114%

S 0.128%

CE 4.25%

The lining bar mechanical property is

Amount of deflection 5.04% bending strength 467MPa～471MPa

Tensile strength 250MPa～269MPa hardness HB187～189

Claims

1, a kind of smelting process of thin-walled high strength compound cast iron is characterized in that by following ratio of components batching:

Steel cuttings 55%～85%

Iron filings 0%～25%

Heavy scrap 0%～10%

Dead head 15%～20%

Add up to 100%

And graphite carburelant 1.5%～4.5%

75% ferrosilicon increases silicea 1.5%～3.5%

Nucleating agent 0.6%～1%

Gestagen (Mn+S) 0.2%～0.7%

(carburelant increases silicea, and nucleating agent, gestagen all with the metal charge percentage calculation, but are not counted in the metal charge).

2, by the described smelting process of thin-walled high strength compound cast iron of claim 1, its feature also is:

A. adding part metals material and carburelant makes it to form fast the molten bath or retains molten iron and do the molten bath.

B. batch charging is repeatedly bred in the stove.

C. with per minute fusing total amount: 1%～0.8% speed is carried out melting.

D. the power before the molten bath forms is 40%～60% of rated output, and power increases to 65%～80% behind the formation molten bath, makes molten iron temperature remain on 1200～1380 ℃ and treats that whole furnace charges are molten clear, and power brings up to 85%～90%, is warming up to 1450～1500 ℃ rapidly.

E.30%～50% nucleating agent adds in stove before tapping a blast furnace.