CN103060693A - Preparation method of medium-low carbon chrome-silicon-manganese martensitic cast steel - Google Patents

Abstract

The invention relates to a preparation method of medium-low carbon chrome-silicon-manganese martensitic cast steel, which comprises the following components (wt%): 0.26-0.4% of C, 0.95-1.3% of Si, 0.70-1.20% of Mn, 0.70-1.10% of Cr, 0.05% of impurity and the balance of Fe. The preparation method comprises the following steps of: smelting; casting; removing sand and polishing; preserving the temperature at 830-860 DEG C for 550-600 seconds; isothermally quenching or incompletely quenching at 180-230 DEG C, and preserving the temperature for 120-240 seconds; preserving the temperature within the interval of 340-430 DEG C for 180-300 seconds; and quenching to room temperature. Steel processed by the method disclosed by the invention has certain plasticity while keeping high intensity; and furthermore, compared with the traditional process, comprehensive mechanical performances of the steel are obviously increased.

Description

A kind of preparation method of middle low-carbon (LC) chrome-silicon manganese martensite cast steel

Technical field

The present invention relates to a kind of preparation method of martensite cast steel, belong to the steel making field, relate in particular to a kind of preparation method who has simultaneously the high middle low-carbon (LC) chrome-silicon manganese martensite cast steel of high strength and high-plasticity and surface hardness.

Background technology

In high-abrasive material was produced, middle low-carbon (LC) chrome-silicon manganese martensite cast steel occupied sizable proportion.Middle low-carbon martensitic steels are generally used for high-intensity quenched and tempered steel, have very high intensity and toughness, and hardening capacity is higher, and cold deformation plasticity is medium, and machinability is good.Because it does not contain precious metal element, low price, multiplex various strength members in making high loading, high speed, such as gear, axle, clutch coupling, sprocket wheel, grinding wheel spindle, axle sleeve, bolt, nut etc., also for the manufacture of part wear-resisting, that working temperature is not high, the welding assembly of variable load, blade, valve plate and non-aggressive pipeline pipe such as high pressure blower, also being applied to the crucial load-carrying members such as space shuttle axle, beam and landing gear etc. and space rocket, nuclear industry, is a commercial class low-alloy super-strength steel the earliest.

As everyone knows, martensite has two kinds of substructures, a kind of twin crystal martensite, and the high fragility of its hardness is large; A kind of is dislocatrion martensite, and its hardness high tenacity is good.Domestic martensite wear resistant steel does not contain Ni, and the cast steel uneven components, therefore the twin crystal martensite content ratio is higher, toughness is tentatively not enough.In addition, middle low-carbon (LC) chrome-silicon manganese martensite cast steel has the temper brittleness tendency, and prior heat treatment process is carried out temper after being generally quenching again.But traditional thermal treatment process can not be taken into account high strength and the well requirement of plasticity and toughness: keep about its tensile strength 1500-1600MPa then plasticity lower (unit elongation is only about 3%-6%), the very high easy generation low stress brittle fracture of crack sensitivity if reduce tempering temperature; Can improve plasticity (unit elongation＞10%) if improve tempering temperature, but intensity declines to a great extent to 1000-1100MPa.For this reason, need the simple and easy to do slack quenching of exploitation-isothermal partition New Technology of Heat Treatment, under the prerequisite that guarantees suitable plasticity, significantly improve the tensile strength of steel, perhaps significantly improve plasticity and toughness in the high-intensity while of assurance, thereby the difference that realizes high strength, high-plasticity cooperates.

Summary of the invention

The present invention will solve the deficiencies in the prior art part, and a kind of preparation method of middle low-carbon (LC) chrome-silicon manganese martensite cast steel is provided.

Technical scheme of the present invention is: a kind of preparation method of middle low-carbon (LC) chrome-silicon manganese martensite cast steel, it is characterized in that, and may further comprise the steps:

1) according to following component configuration raw material (wt%):

C：0.26～0.4?　　

Si：0.95～1.3?　　

Mn：0.70～1.20

Cr：0.70～1.10

Impurity:＜0.05

Surplus is Fe;

In the medium frequency response ratio melting, first melting carbon steel, ferrochrome is packed into material, and after furnace charge melted clearly, furnace temperature reached 1580 ~ 1600 ℃ and adds ferrosilicon, ferromanganese, and ferrosilicon, ferromanganese material piece size are 50 ~ 60mm, then carry out molten alloy;

2) with coming out of the stove behind the aluminium deoxidation, adopt clay-bonded sand, tidal stencils, be cast into foundry goods, carry out sand removal, polishing surface treatment after the cooling;

3) the foundry goods steel that makes is incubated 550～600s under 830 ℃～860 ℃ temperature and finishes whole austenitizings processing;

4) through after the step 3), under 180～230 ℃ of temperature, carry out isothermal quenching or slack quenching again, insulation 120s～240s;

5) will through the steel part of step 4) processing, in 340 ℃～430 ℃ temperature range, be incubated 180s～300s, and then be quenched to room temperature.

The present invention makes middle low-carbon (LC) chrome-silicon manganese martensite cast steel foundry goods by suitable component and proportioning first by lot of experiments, then in thermal treatment process, the foundry goods steel that makes is heated to 830 ℃～860 ℃, namely is higher than A _C3Be incubated 550～600s under above 40 ℃～70 ℃ temperature, process to finish whole austenitizings, wherein A _C3When heating for hypoeutectoid steel, all ferrites all change austenitic temperature into; Then at 180～230 ℃, namely be lower than the martensite start temperature M of cast steel _sCarry out isothermal quenching or slack quenching under following 120-70 ℃ the temperature, insulation 120s～240s, obtain partial martensite and do not change austenite, then in 340 ℃～430 ℃ temperature range, be incubated, make the before formation martensite of carbon to not changing in the austenite diffusion and making it stabilization, be quenched at last room temperature, obtain the heterogeneous structure that is formed by martensite and rich carbon austenitic.With respect to traditional Q-tempering technique, thermal treatment process of the present invention can make martensitic steel obviously improve plasticity and toughness under the prerequisite that keeps strength level.

Beneficial effect of the present invention is, the tensile strength of the middle low-carbon (LC) chrome-silicon manganese martensite cast steel that makes through method of the present invention reaches more than the 1600MPa, and plasticity is more than 10% simultaneously.Guaranteeing that this steel series keeps high-intensity and has simultaneously certain plasticity concurrently, and comprehensive mechanical property significantly improves than traditional Q-tempering thermal treatment process.

Embodiment

Below in conjunction with embodiment the present invention is more specifically described, but embodiments of the present invention are not limited to this.

Embodiment 1

1) according to following component configuration raw material (wt%):

C：0.26?　　

Si：0.95?　　

Mn：0.70

Cr：0.70

Impurity:＜0.05

Surplus is Fe;

In the medium frequency response ratio melting, first melting carbon steel, ferrochrome is packed into material, and after furnace charge melted clearly, furnace temperature reached 1580 ℃ and adds ferrosilicon, ferromanganese, and ferrosilicon, ferromanganese material piece size are 60mm, then carry out molten alloy;

2) with coming out of the stove behind the aluminium deoxidation, adopt clay-bonded sand, tidal stencils, be cast into foundry goods, carry out sand removal, polishing surface treatment after the cooling;

3) the foundry goods steel that makes is incubated 550s under 830 ℃ temperature and finishes whole austenitizings processing;

4) through after the step 3), under 180 ℃ of temperature, carry out isothermal quenching or slack quenching again, insulation 120s;

5) will through the steel part of step 4) processing, in 340 ℃ temperature range, be incubated 180s, and then be quenched to room temperature.

Through above-mentioned steps, the heterogeneous structure of the steel part that obtains for being formed by low carbon martensite and rich carbon austenitic, after tested, tensile strength is 1640MPa, and plasticity reaches 11.9%.

 

Embodiment 2

1) according to following component configuration raw material (wt%):

C：0.28?　　

Si：1.1?　　

Mn：0.90

Cr：0.95

Impurity:＜0.05

Surplus is Fe;

In the medium frequency response ratio melting, first melting carbon steel, ferrochrome is packed into material, and after furnace charge melted clearly, furnace temperature reached 1590 ℃ and adds ferrosilicon, ferromanganese, and ferrosilicon, ferromanganese material piece size are 50mm, then carry out molten alloy;

2) with coming out of the stove behind the aluminium deoxidation, adopt clay-bonded sand, tidal stencils, be cast into foundry goods, carry out sand removal, polishing surface treatment after the cooling;

3) the foundry goods steel that makes is incubated 580s under 840 ℃ temperature and finishes whole austenitizings processing;

4) through after the step 3), under 210 ℃ of temperature, carry out isothermal quenching or slack quenching again, insulation 180s;

5) will through the steel part of step 4) processing, in 390 ℃ temperature range, be incubated 230s, and then be quenched to room temperature.

Through above-mentioned steps, the heterogeneous structure of the steel part that obtains for being formed by low carbon martensite and rich carbon austenitic, after tested, tensile strength is 1730MPa, and plasticity reaches 13.1%.

 

Embodiment 3

1) according to following component configuration raw material (wt%):

C：?0.4?　　

Si：?1.3?　　

Mn：?1.20

Cr：?1.10

Impurity:＜0.05

Surplus is Fe;

In the medium frequency response ratio melting, first melting carbon steel, ferrochrome is packed into material, and after furnace charge melted clearly, furnace temperature reached 1600 ℃ and adds ferrosilicon, ferromanganese, and ferrosilicon, ferromanganese material piece size are 60mm, then carry out molten alloy;

2) with coming out of the stove behind the aluminium deoxidation, adopt clay-bonded sand, tidal stencils, be cast into foundry goods, carry out sand removal, polishing surface treatment after the cooling;

3) the foundry goods steel that makes is incubated 600s under 860 ℃ temperature and finishes whole austenitizings processing;

4) through after the step 3), under 230 ℃ of temperature, carry out isothermal quenching or slack quenching again, insulation 240s;

5) will through the steel part of step 4) processing, in 440 ℃ temperature range, be incubated 180s～300s, and then be quenched to room temperature.

Through above-mentioned steps, the heterogeneous structure of the steel part that obtains for being formed by low carbon martensite and rich carbon austenitic, after tested, tensile strength is 1710MPa, and plasticity reaches 12.7%.

Claims (1)

1. the preparation method of low-carbon (LC) chrome-silicon manganese martensite cast steel in a kind is characterized in that, may further comprise the steps:

1) according to following component configuration raw material (wt%):

C：0.26～0.4?　　

Si：0.95～1.3?　　

Mn：0.70～1.20

Cr：0.70～1.10

Impurity:＜0.05

Surplus is Fe;

In the medium frequency response ratio melting, first melting carbon steel, ferrochrome is packed into material, and after furnace charge melted clearly, furnace temperature reached 1580 ~ 1600 ℃ and adds ferrosilicon, ferromanganese, and ferrosilicon, ferromanganese material piece size are 50 ~ 60mm, then carry out molten alloy;

2) with coming out of the stove behind the aluminium deoxidation, adopt clay-bonded sand, tidal stencils, be cast into foundry goods, carry out sand removal, polishing surface treatment after the cooling;

3) the foundry goods steel that makes is incubated 550～600s under 830 ℃～860 ℃ temperature and finishes whole austenitizings processing;

4) through after the step 3), under 180～230 ℃ of temperature, carry out isothermal quenching or slack quenching again, insulation 120s～240s;

5) will through the steel part of step 4) processing, in 340 ℃～430 ℃ temperature range, be incubated 180s～300s, and then be quenched to room temperature.