阅读说明：本技术 一种用返回料冶炼模具钢h13的方法 (Method for smelting die steel H13 by using return materials ) 是由 石春明 刘少友 马德克 徐增力 于 2021-09-09 设计创作，主要内容包括：本发明涉及一种用返回料冶炼模具钢H13的方法,包括下述步骤：(1)装料前向炉底装石灰和含铬钼的钢返回料；(2)送电熔化,当炉料熔化70%～85%时,对炉门及渣线附近的大块炉料进行吹氧助熔；(3)当钢水温度≥1550℃时,进行吹氧脱碳升温,同时向炉中加入石灰,降低钢渣熔点,增强钢渣流动性；再向钢水中加入硅铁粉,将渣中的Cr还原回钢水中,过程中尽量不放渣,确保合金回收率；(4)向钢水中加入石灰,将还原渣碱度调整至2.0～2.5；(5)当钢水温度升高至1640～1680℃,炉渣为黄或白渣时取样分析钢水化学成分,成分合格时出钢；本发明方法,可有效提高冶炼过程中铬的收得率,降低生产成本,提高钢品质。(The invention relates to a method for smelting die steel H13 by using return materials, which comprises the following steps: (1) before charging, lime and steel return containing chromium and molybdenum are charged at the bottom of the furnace; (2) feeding electricity for melting, and blowing oxygen for fluxing bulk furnace burden near a furnace door and a slag line when 70-85% of the furnace burden is melted; (3) when the temperature of the molten steel is more than or equal to 1550 ℃, oxygen blowing, decarbonization and heating are carried out, and meanwhile, lime is added into the furnace, so that the melting point of the steel slag is reduced, and the fluidity of the steel slag is enhanced; adding ferrosilicon powder into the molten steel, reducing Cr in the slag back into the molten steel, and avoiding slag discharge as much as possible in the process so as to ensure the recovery rate of the alloy; (4) adding lime into the molten steel, and adjusting the alkalinity of the reducing slag to 2.0-2.5; (5) when the temperature of the molten steel rises to 1640-1680 ℃, sampling and analyzing chemical components of the molten steel when the slag is yellow or white slag, and tapping when the components are qualified; the method can effectively improve the yield of chromium in the smelting process, reduce the production cost and improve the steel quality.)

1. A method for smelting die steel H13 by using return materials comprises the following steps:

(1) before charging, lime is charged into the furnace bottom according to the proportion of 8-12 kg/t molten steel, and then 28-33 t of steel return containing chromium and molybdenum is charged;

(2) feeding electricity for melting, and blowing oxygen for fluxing a small amount of large furnace burden near a furnace door and a slag line when the furnace burden is 70-85% melted, wherein the oxygen pressure is 0.3-0.5 Mpa;

(3) when the temperature of the molten steel is more than or equal to 1550 ℃, oxygen blowing, decarbonizing and heating are carried out, the oxygen pressure is 0.8-1.2 MPa, and meanwhile, lime is added into the furnace according to the proportion of 10-12 kg/t of molten steel, so that the melting point of the steel slag is reduced, and the fluidity of the steel slag is enhanced; adding ferrosilicon powder into the molten steel according to the proportion of 4.8-5.1 kg/t of molten steel, reducing Cr in the slag back into the molten steel, and avoiding slag discharge as much as possible in the reduction process of adding the ferrosilicon powder, so as to ensure the recovery rate of alloy;

(4) adding lime into the molten steel, and adjusting the alkalinity of the reducing slag to 2.0-2.5;

(5) and when the temperature of the molten steel is raised to 1640-1680 ℃, sampling and analyzing chemical components of the molten steel when the slag is yellow or white slag, and tapping when all the components reach a middle-off line.

2. The method for smelting die steel H13 from return material according to claim 1, wherein the method comprises the following steps: the steel return material containing chromium and molybdenum refers to high-alloy chromium and molybdenum waste dies and leftover materials thereof, such as waste dies or leftover materials produced in steel production, such as H13, 8418, P91, low-copper scrap steel and the like, wherein the copper content of the low-copper scrap steel after the steel is melted is lower than 0.06%.

3. The method for smelting die steel H13 from return material according to claim 1, wherein the method comprises the following steps: the die steel H13 contains the following elements in percentage by weight: cr: 5.1-5.4%, Mo: 1.35-1.45%, V: 0.9 to 1.05 percent.

Technical Field

The invention relates to the technical field of steel materials, in particular to a method for smelting die steel H13 by using return materials.

Background

The die steel H13 is 4Cr5MoSiV1 corresponding to the national standard, the alloy element accounts for about 8 percent, and belongs to the medium alloy steel series, wherein: cr: 5.1-5.4%, Mo: 1.35-1.45%, V: 0.9 to 1.05 percent. There are generally two manufacturing methods: the first method comprises the following steps: adding alloy for smelting, oxidizing a scrap steel EBT furnace, adding alloy after tapping, LF refining, VD vacuum treatment and die casting, and performing second step: smelting a return material, oxidizing the return material in an EBT furnace, LF refining, VD vacuum treatment and die casting. The first manufacturing method is relatively simple to operate, but chemical components are guaranteed by adding alloy, the cost is high, and the production and operation are not facilitated. According to research, a plurality of high-alloy chromium-molybdenum waste dies and scraps, such as H13, 8418, P91 and the like, are available on the market, so that a plurality of manufacturers adopt a second manufacturing method or a second method to add a small amount of alloy.

The return material is adopted for smelting, when the EBT furnace is blown with oxygen for decarburization, a large amount of chromium is easily oxidized, the yield of the chromium is low, and in order to ensure chemical components, the addition amount of the chromium needs to be increased in a refining furnace, so that the smelting cost is high. Meanwhile, because the addition amount of the alloy is increased, harmful elements in steel grades are increased, and the quality of steel is reduced.

Therefore, for producing H13 die steel by adopting return material smelting, the problems that the yield of chromium is reduced, a large amount of chromium alloy needs to be supplemented, so that harmful elements in steel are increased, and the steel quality is reduced are solved, and the technical problem in the industry for a long time is solved.

Disclosure of Invention

The invention aims to provide a method for smelting die steel H13 by using return materials, aiming at the problems that when the prior art adopts the return materials to smelt the die steel H13, the yield of chromium is easy to decrease, and a large amount of chromium alloy needs to be supplemented, so that harmful elements of steel types are increased, and the quality of steel is reduced. The method can effectively improve the yield of chromium in the smelting process, reduce the production cost and improve the steel quality.

In order to achieve the above object, the present invention provides a method for smelting die steel H13 from a return material, comprising the steps of:

(1) before charging, lime is charged into the furnace bottom according to the proportion of 8-12 kg/t molten steel, and 28-33 t of steel return containing chromium and molybdenum is charged;

(2) feeding electricity for melting, and blowing oxygen for fluxing a small amount of large furnace burden near a furnace door and a slag line when the furnace burden is 70-85% melted, wherein the oxygen pressure is 0.3-0.5 Mpa;

(3) when the temperature of the molten steel is more than or equal to 1550 ℃, oxygen blowing, decarbonizing and heating are carried out, the oxygen pressure is 0.8-1.2 MPa, and meanwhile, lime is added into the furnace according to the proportion of 10-12 kg/t of molten steel, so that the melting point of the steel slag is reduced, and the fluidity of the steel slag is enhanced; adding ferrosilicon powder into the molten steel according to the proportion of 4.8-5.1 kg/t of molten steel, reducing Cr in the slag back into the molten steel, and avoiding slag discharge as much as possible in the reduction process of adding the ferrosilicon powder, so as to ensure the recovery rate of alloy;

(4) adding lime into the molten steel, and adjusting the alkalinity of the reducing slag to 2.0-2.5;

(5) and when the temperature of the molten steel rises to 1640-1680 ℃ (the tapping temperature is determined according to the temperature of a steel ladle, a cold ladle is taken on line, a hot ladle is taken off line), when the slag is yellow or white slag, sampling and analyzing chemical components of the molten steel, and tapping when all the components reach the middle line and the lower line.

The steel return material containing chromium and molybdenum refers to high-alloy chromium and molybdenum waste dies and leftover materials thereof, such as waste dies or leftover materials produced in steel production, such as H13, 8418, P91, low-copper scrap steel and the like, wherein the copper content of the low-copper scrap steel after the steel is melted is lower than 0.06%.

The die steel H13 contains the following elements in percentage by weight: cr: 5.1-5.4%, Mo: 1.35-1.45%, V: 0.9 to 1.05 percent.

The method is obtained after repeated research, reasoning and experimental verification in long-term working practice by the inventor, and the process and process parameters adopted in the method are as follows:

(1) lime is filled at the bottom of the furnace before charging, so that the aims of protecting the bottom of the furnace and dephosphorizing at low temperature in advance can be fulfilled;

(2) when the furnace charge is electrified and melted to 70-85%, a small amount of large furnace charge near the furnace door and the slag line is blown with oxygen to assist melting, so that the melting speed of the charge in the low-temperature region can be increased, and the uniformity of the furnace charge is ensured;

(3) when the temperature of the molten steel is more than or equal to 1550 ℃, oxygen blowing, decarbonizing and heating are carried out, the oxygen pressure is 0.8-1.2 MPa, and meanwhile, lime is added into the furnace according to the proportion of 10-12 kg/t of molten steel, so that the melting point of the steel slag is reduced, and the fluidity of the steel slag is enhanced; adding ferrosilicon powder with stronger affinity with oxygen into the molten steel according to the proportion of 4.8-5.1 kg/t of molten steel, reducing Cr with weaker affinity with oxygen in slag back into the molten steel, and avoiding discharging slag as much as possible in the reduction process of adding the ferrosilicon powder, thereby ensuring the recovery rate of alloy;

(4) adding lime into the molten steel, and adjusting the alkalinity of the reducing slag to 2.0-2.5, so that good fluidity of the slag is ensured, and reduction recovery of chromium in the slag is facilitated;

(5) when the temperature of the molten steel is increased to 1640-1680 ℃ (the tapping temperature is determined according to the temperature of a steel ladle, a cold ladle is taken on line, a hot ladle is taken off line), when the slag is yellow or white slag, the chemical components of the molten steel are sampled and analyzed, and when all the components reach the middle line and the lower line, the molten steel is tapped: the proper superheat degree of the molten steel is ensured, the requirements of a later pouring process are met, the middle-end and lower-end line control can ensure that the alloy components do not exceed the upper limit, and the alloy can be properly supplemented in a refining process in case that the alloy components are lower than the lower limit.

Compared with the prior art, the invention has the following advantages:

(1) the method can reduce the loss of chromium in the return material, improve the yield of the chromium by more than 3 percent, reduce the production cost and improve the economic benefit of enterprises;

(2) the invention can digest waste secondary resources on the market, so that the waste resources are fully utilized;

(3) by adopting the method, additional harmful elements cannot be generated in the steel, and the quality of the steel is improved.

Detailed Description

In order to better explain the technical solution of the present invention, the technical solution of the present invention is further described below with reference to specific examples, which are only exemplary to illustrate the technical solution of the present invention and do not limit the present invention in any way.

Example 1

In the embodiment, an EBT furnace is adopted, an H13 return material is added to smelt 25 tons of H13 molten steel, and the return material adopts an H13 return material (H13 waste dies, H13 processing steel scraps and the like), and the concrete conditions are as follows:

a method for smelting die steel H13 by using return materials comprises the following steps:

(1) the EBT furnace is filled with 270kg lime pad hearth firstly, and then H13 return material 28t is filled;

(2) feeding electricity for melting, and blowing oxygen for fluxing a small amount of large furnace burden near a furnace door and a slag line when the furnace burden is 80-83% melted, wherein the oxygen pressure is 0.3-0.4 Mpa;

(3) when the temperature of the molten steel is more than or equal to 1550 ℃, oxygen blowing, decarbonizing and heating are carried out, and the oxygen pressure is 1.0-1.2 MPa; at the same time, 270kg of lime is added into the furnace to reduce the melting point of the steel slag and enhance the fluidity of the steel slag; adding 120kg ferrosilicon powder into the molten steel, reducing Cr in the slag into the molten steel, and avoiding slag discharge as much as possible in the reduction process of adding the ferrosilicon powder to ensure the recovery of alloy;

(4) then adding lime into the molten steel, and adjusting the alkalinity of the reducing slag to 2.3;

(5) when the temperature is increased to 1660 ℃, sampling and analyzing the chemical components of the molten steel when the slag is yellow slag, and tapping when all the components reach the middle-lower line;

after the smelting is finished, 25.3 tons of H13 molten steel with qualified components are obtained, and through detection, in the H13 molten steel smelted by the method of the embodiment, the ratio of Cr: 5.25%, Mo: 1.40%, V: 1.0, all meet the requirements of steel components, and other components can be adjusted in the refining process.

Compared with the traditional method for smelting H13 steel by adopting return materials, the method of the embodiment has the advantages that 12.1Kg of ferrochrome is less added, the production cost is reduced by 145 yuan/ton, and by adopting the method, additional harmful elements cannot be generated in the steel, so that the quality of the steel is improved.

Example 2

In the embodiment, an EBT furnace is adopted, 8418 steel return is added to smelt 30 tons of H13 molten steel, the return adopts 8418 return (8418 waste dies, 8418 processing steel scraps and the like), and the concrete conditions are as follows:

a method for smelting die steel H13 by using return materials comprises the following steps:

(1) the EBT furnace was charged with 300kg of lime pad hearth first and then with 8418 tons of return material 33 tons.

(2) Feeding electricity for melting, and blowing oxygen for fluxing a small amount of large furnace burden near a furnace door and a slag line when 82-85% of furnace burden is melted, wherein the oxygen pressure is 0.45-0.5 Mpa;

(3) when the temperature of the molten steel is more than or equal to 1550 ℃, oxygen blowing, decarbonizing and heating are carried out, and the oxygen pressure is 0.8-1.0 MPa; simultaneously, 300kg of lime is added into the furnace to reduce the melting point of the steel slag and enhance the fluidity of the steel slag; adding 150kg ferrosilicon powder into the molten steel, reducing Cr in the slag into the molten steel, and avoiding slag discharge as much as possible in the reduction process of adding the ferrosilicon powder to ensure the recovery of alloy;

(4) then adding lime into the molten steel, and adjusting the alkalinity of the reducing slag to 2.5;

(5) when the temperature rises to 1670 ℃, sampling and analyzing the chemical components of the molten steel when the slag is yellow slag, and tapping when all the components reach the middle-lower line;

after the smelting is finished, 29.5 tons of H13 molten steel with qualified components are obtained, and through detection, in the H13 molten steel smelted by the method of the embodiment, the ratio of Cr: 5.2%, Mo: 1.30%, V: 1.05%, and other components can be adjusted in the refining process.

Compared with the traditional method for smelting H13 steel by adopting return materials, the method of the embodiment has the advantages that the ferrochrome alloy is less than 10Kg/t of steel, the production cost is reduced by about 120 yuan/ton of steel, and by adopting the method, additional harmful elements cannot be generated in the steel, so that the quality of the steel is improved.

Example 3

In the embodiment, an EBT furnace is adopted, P91 steel return and low-copper scrap steel are added to smelt 25 tons of H13 molten steel, the return adopts P91 return (P91 waste die, P91 processing steel scrap and the like, and the copper content of the low-copper scrap steel after the steel is melted is lower than 0.06 percent), and the concrete conditions are as follows:

a method for smelting die steel H13 by using return materials comprises the following steps:

(1) firstly, loading 250kg of lime pad furnace bottom into an EBT furnace, then loading 18 tons of P91 return material, and then adding 12 tons of low-copper scrap steel;

(2) feeding electricity for melting, and blowing oxygen for fluxing a small amount of large furnace burden near a furnace door and a slag line when the furnace burden is 70-75% melted, wherein the oxygen pressure is 0.3-0.45 Mpa;

(3) when the temperature of the molten steel is more than or equal to 1550 ℃, oxygen blowing, decarbonizing and heating are carried out, and the oxygen pressure is 0.9-1.1 MPa; at the same time, 270kg of lime is added into the furnace to reduce the melting point of the steel slag and enhance the fluidity of the steel slag; adding 120kg ferrosilicon powder into the molten steel, reducing Cr in the slag into the molten steel, and avoiding slag discharge as much as possible in the reduction process of adding the ferrosilicon powder to ensure the recovery of alloy;

(4) then adding lime into the molten steel, and adjusting the alkalinity of the reducing slag to 2.0;

(5) when the temperature is raised to 1640 ℃, sampling and analyzing chemical components of the molten steel when the slag is white slag, and tapping when all the components reach a middle-lower line;

after the smelting is finished, 25.1 tons of H13 molten steel with qualified components are obtained, and through detection, in the H13 molten steel smelted by the method of the embodiment, the ratio of Cr: 5.1%, Mo: 1.36%, V: 1.02%, and other components can be adjusted in the refining process.

Compared with the traditional method for smelting H13 steel by adopting return materials, the method of the embodiment has the advantages that 12Kg of ferrochrome alloy is added per ton of steel, the production cost is reduced by 144 yuan per ton of steel, and by adopting the method, additional harmful elements cannot be generated in the steel, so that the quality of the steel is improved.

Example 4

In the embodiment, an EBT furnace is adopted, and an H13 steel return, a P91 steel return and low-copper scrap are added to smelt 30 tons of H13 molten steel, and the return adopts an H13 steel return and a P91 steel return (H13 waste die, P91 waste die, waste steel scrap and the like, the copper content of the low-copper scrap after the steel is melted is less than 0.06%), specifically as follows:

a method for smelting die steel H13 by using return materials comprises the following steps:

(1) firstly, 300Kg of lime pad furnace bottom is loaded into an EBT furnace, then 10 tons of H13 return material, 13 tons of P91 return material and 10 tons of low-copper scrap steel are loaded;

(2) feeding electricity for melting, and blowing oxygen for fluxing a small amount of large furnace burden near a furnace door and a slag line when the furnace burden is 75-80% melted, wherein the oxygen pressure is 0.3-0.40 Mpa;

(3) when the temperature of the molten steel is more than or equal to 1550 ℃, oxygen blowing, decarbonizing and heating are carried out, and the oxygen pressure is 0.8-1.0 MPa; simultaneously, 300kg of lime is added into the furnace to reduce the melting point of the steel slag and enhance the fluidity of the steel slag; adding 150kg ferrosilicon powder into the molten steel, reducing Cr in the slag into the molten steel, and avoiding slag discharge as much as possible in the reduction process of adding the ferrosilicon powder to ensure the recovery of alloy;

(4) then adding lime into the molten steel, and adjusting the alkalinity of the reducing slag to 2.2;

(5) when the temperature is increased to 1680 ℃, sampling and analyzing chemical components of the molten steel when the slag is white slag, and tapping when all the components reach the middle and lower line;

after the smelting is finished, 30.1 tons of H13 molten steel with qualified components are obtained, and through detection, in the H13 molten steel smelted by the method of the embodiment, the ratio of Cr: 5.15%, Mo: 1.36%, V: 0.95%, and other components can be adjusted in the refining step.

Compared with the traditional method for smelting H13 steel by adopting return materials, the method of the embodiment has the advantages that 11.5Kg of ferrochrome is less added, the production cost is reduced by 138 yuan, and by adopting the method of the invention, additional harmful elements cannot be generated in the steel, thereby being beneficial to improving the quality of the steel.

The embodiment shows that the method for smelting H13 die steel obviously reduces the addition of ferrochrome, improves the chromium yield by more than 3 percent and reduces the production cost by 2 to 3 percent compared with the traditional method for smelting H13 die steel by adopting return materials, does not cause additional harmful elements in steel, and is beneficial to improving the quality of the steel.

The embodiments of the present invention are merely preferred examples, and are not intended to limit the scope of the claims. The embodiments described above are merely specific examples of the present invention exemplified for explaining the present invention, and do not limit the present invention in any way, and any insubstantial changes from the above-described contents and forms without departing from the scope of the present invention are considered to fall within the scope of the present invention as claimed. The invention is not limited to the specific embodiments described above.