CN116833244A - Thermal processing technology of 1800 megapascal high-strength steel mixed crystal - Google Patents

Abstract

The invention discloses a thermal processing technology for 1800 MPa high-strength steel mixed crystal, which includes the following steps: mixing the raw materials and pouring them into a furnace for smelting, and pouring the melted raw materials into a refining furnace for refining; using continuous casting In the steel method, molten steel is poured into the mold and solidified into a strip-shaped billet in the mold; the solidified billet is cut into segments through cutting equipment to become segmented steel billets; the segmented steel billets are heated through a heating furnace and passed through The rolling mill hot-rolls the heated segmental billet, and after multiple rollings, a hot-rolled plate is prepared. The present invention can increase the heating speed and heating effect of the steel billet during hot rolling through alternately arranged induction heating furnaces and holding furnaces, and adopts new heating and heat preservation methods and process parameters, which can greatly reduce the temperature difference between the inside and outside of the steel billet, thereby avoiding the need for hot rolling. When cracks occur, the deformation amount can be increased, which can meet the large plastic deformation requirements of high-strength steel mixed crystals.

Description

A thermal processing technology for 1800 MPa high-strength steel mixed crystal

Technical field

The invention relates to the technical field of high-strength steel, specifically a thermal processing technology for mixed crystals of 1800 MPa high-strength steel.

Background technique

High-strength steel mixed grain refers to a kind of steel with high-strength properties, and its organizational structure contains mixed phases and multiple grain orientations. Mixed crystal means the presence of two or more phases (crystal structures) in a material that differ in aspects such as atomic arrangement, lattice parameters, and orientation. High-strength steel mixed crystals are usually composed of iron-based alloys (such as iron, carbon, manganese, etc.) and the addition of other alloying elements (such as molybdenum, chromium, titanium, etc.). High-strength steel mixed crystals are formed to improve properties such as strength, hardness and wear resistance in structural materials. By adjusting the alloy composition and heat treatment process, microstructure control and performance optimization of mixed grains of high-strength steel can be achieved. Among them, the mixed crystal phase in the microstructure can hinder dislocation slip and grain boundary movement, thereby improving the strength and hardness of the material.

1800 MPa high-strength steel mixed crystal is a structural material with high strength and wear resistance. It is widely used in aviation, automobiles, construction, machinery and other fields; it has high tensile strength, yield strength and impact toughness. It also has good corrosion resistance and weldability; by controlling the formation and distribution of the mixed crystal phase, the mechanical properties of the material can be further adjusted to meet various specific engineering needs. However, when performing large-deformation thermal processing on 1800 MPa high-strength steel mixed crystal, the current thermal processing technology requires heating before rolling. Due to the short heating time, there will be a certain temperature difference between the inside and outside of the slab, which is prone to occur during rolling. cracks, and can only achieve a limited amount of deformation, which cannot meet the large plastic deformation requirements of high-strength steel mixed crystals.

To sum up, the existing technology still has many shortcomings in solving the problem of large deformation thermal processing of mixed crystals of 1800 MPa high-strength steel. The present invention aims to overcome the shortcomings of the existing technology and provide a thermal processing process of 1800 MPa high-strength steel mixed crystal to improve the plastic deformation ability of the material and meet actual production needs.

Contents of the invention

The technical problem to be solved by the present invention is to overcome the existing defects and provide a thermal processing technology for 1800 MPa high-strength steel mixed crystal. By alternately setting the induction heating furnace 2 and the holding furnace 3, the quality of the steel billet during hot rolling can be improved. The heating speed and heating effect, and the use of new heating and insulation methods and process parameters, can greatly reduce the temperature difference between the inside and outside of the steel billet, thereby avoiding cracks during hot rolling, and at the same time increasing the amount of deformation, which can meet the large demand for mixed crystals of high-strength steel. The amplitude plastic deformation requirement can effectively solve the problems in the background technology.

In order to achieve the above object, the present invention provides the following technical solution: a thermal processing process of 1800 MPa high-strength steel mixed crystal, including the following steps:

S1. Mix the raw materials and pour them into the furnace for smelting, and pour the melted raw materials into the refining furnace for refining;

S2. Use the continuous steel casting method to pour the molten steel into the mold so that it solidifies into a strip-shaped cast slab;

S3. Cut the solidified billet into segments through cutting equipment to become segmented steel billets;

S4. Heat the segmented steel billet through the heating furnace, and hot-roll the heated segmented steel billet through the rolling mill. After multiple rollings, a hot-rolled plate is prepared. After the hot rolling is completed, it is sprayed with water to cool down;

S5. Cold-roll the hot-rolled plate to obtain a cold-rolled plate;

S6. After the cold-rolled plate is continuously annealed, it is then quenched to obtain a heat-treated plate for hot-formed parts.

As a preferred technical solution of the present invention, during refining in S1, a mixed gas of argon and oxygen is injected to perform decarburization, and high-pressure gas is blown in to drive the molten iron to flow, so that impurities float to the upper side, and samples are taken for detection. To confirm that the ingredients are qualified.

As a preferred technical solution of the present invention, in S3, the length of the cut steel billet is 5-6 meters.

As a preferred technical solution of the present invention, in S4, the heated steel billet is dephosphorized with high-pressure water to remove the oxide layer; specifically, under the effects of erosion, peeling, and thermal explosion of the high-pressure water jet, the steel billet is The scales on the surface detached.

As a preferred technical solution of the present invention, in S4, during the multiple rolling processes, the slab is heated, maintained and dephosphorized through online heating equipment for each 3-5 rolling passes. The online heating equipment includes The conveyor roller is used to convey the slab, and the conveyor roller is provided with multiple sets of induction heating furnaces and holding furnaces arranged in sequence. The parts corresponding to the conveyor roller and the induction heating furnace are hollow, so that the induction heating furnace can perform heating on the slab. heating.

As a preferred technical solution of the present invention, the high-pressure water phosphorus removal equipment is located between the online heating equipment and the rolling mill.

Compared with the prior art, the beneficial effects of the present invention are:

The example of the present invention solves the large deformation thermal processing process of 1800 MPa high-strength steel mixed crystal. The heating speed and heating effect of the steel billet during hot rolling can be improved by alternating induction heating furnaces and holding furnaces, and a new heating and insulation method is adopted. The method and process parameters can greatly reduce the temperature difference between the inside and outside of the steel billet, thereby avoiding cracks during hot rolling. At the same time, it can increase the amount of deformation and meet the needs for large plastic deformation of high-strength steel mixed crystals.

Description of the drawings

Figure 1 is a schematic structural diagram of the present invention.

In the picture: 1 conveyor roller, 2 induction heating furnace, 3 holding furnace.

Detailed ways

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only some of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts fall within the scope of protection of the present invention.

Please refer to Figure 1. The present invention provides a technical solution:

Example 1:

A thermal processing process for 1800 MPa high-strength steel mixed crystal, including the following steps:

S1. Mix the raw materials and pour them into the furnace for smelting, and pour the melted raw materials into the refining furnace for refining; during refining, inject a mixed gas of argon and oxygen to perform decarburization, and blow in high-pressure gas to drive the molten iron Flow to float impurities to the upper side, and take samples for testing to confirm that the ingredients are qualified;

S2. Use the continuous steel casting method to pour the molten steel into the mold so that it solidifies into a strip-shaped cast slab;

S3. Use the cutting equipment to cut the solidified cast billet into segments to become segmented steel billets. The length of the cut billets is 5-6 meters;

S4. The segmented steel billet is heated through the heating furnace. The heated steel billet is dephosphorized with high-pressure water to remove the oxide layer; specifically: under the action of erosion, peeling, and thermal explosion effects of the high-pressure water jet, the surface of the steel billet is The scales detach;

The heated segmented steel billet is hot-rolled through the rolling mill. After multiple rolling, the hot-rolled plate is prepared. During the multiple rolling process, the slab is heated, maintained and removed by online heating equipment for each 3 rolling passes. For phosphorus operation, the online heating equipment includes a conveyor roller 1 for conveying slabs, and the conveyor roller 1 is provided with multiple sets of induction heating furnaces 2 and holding furnaces 3 that are arranged crosswise in sequence. The conveyor roller 1 corresponds to the induction heating furnace 2. It is set up hollow so that the induction heating furnace 2 can heat the slab. The induction heating furnace 2 can heat the steel billet to a temperature of 1300°C and the heating time is 30 minutes. The holding furnace can keep the steel billet at a temperature of 1200°C and the heat preservation time is 90 minutes. Each round The temperature of the steel billet before rolling is not lower than 900℃;

After the hot rolling is completed, it is sprayed with water to cool down;

S5. Cold-roll the hot-rolled plate to obtain a cold-rolled plate;

S6. After the cold-rolled plate is continuously annealed, the annealing is divided into three stages. In the first stage, the annealing temperature is 750°C, and the annealing holding time is 3 minutes; in the second stage, the annealing temperature is 500°C, and the holding time is 1 minute; The third stage is room temperature; and the time for the first stage temperature to drop to the second stage is kept at 20 minutes, and the time for the second stage temperature to drop to the third stage is kept at 20 minutes;

Then it is quenched at a quenching temperature of 800°C and a holding time of 5 minutes, and then quenched to room temperature to obtain a heat-treated plate for thermoformed parts.

Furthermore, high-pressure water phosphorus removal equipment is located between the online heating equipment and the rolling mill.

Example 2:

A thermal processing process for 1800 MPa high-strength steel mixed crystal, including the following steps:

S1. Mix the raw materials and pour them into the furnace for smelting, and pour the melted raw materials into the refining furnace for refining; during refining, inject a mixed gas of argon and oxygen to perform decarburization, and blow in high-pressure gas to drive the molten iron Flow to float impurities to the upper side, and take samples for testing to confirm that the ingredients are qualified;

S2. Use the continuous steel casting method to pour the molten steel into the mold so that it solidifies into a strip-shaped cast slab;

S3. Use the cutting equipment to cut the solidified cast billet into segments to become segmented steel billets. The length of the cut billets is 5-6 meters;

S4. The segmented steel billet is heated through the heating furnace. The heated steel billet is dephosphorized with high-pressure water to remove the oxide layer; specifically: under the action of erosion, peeling, and thermal explosion effects of the high-pressure water jet, the surface of the steel billet is The scales detach;

The heated segmented steel billet is hot-rolled through the rolling mill. After multiple rolling, the hot-rolled plate is prepared. During the multiple rolling process, the slab is heated, maintained and removed by online heating equipment for each 4 rolling passes. For phosphorus operation, the online heating equipment includes a conveyor roller 1 for conveying slabs, and the conveyor roller 1 is provided with multiple sets of induction heating furnaces 2 and holding furnaces 3 that are arranged crosswise in sequence. The conveyor roller 1 corresponds to the induction heating furnace 2. It is set up hollow so that the induction heating furnace 2 can heat the slab. The heating temperature of the steel billet by the induction heating furnace is 1350°C and the heating time is 45min; the insulation temperature of the steel billet by the holding furnace is 1250℃ and the insulation time is 105min. Each round of rolling The temperature of the steel billet before processing is not lower than 900℃;

After the hot rolling is completed, it is sprayed with water to cool down;

S5. Cold-roll the hot-rolled plate to obtain a cold-rolled plate;

S6. After the cold-rolled plate is continuously annealed, the annealing is divided into three stages. The first stage annealing temperature is 800°C, and the annealing holding time is 4 minutes; the second stage annealing temperature is 600°C, and the holding time is 2 minutes; the third stage The stage is room temperature; and the time for the temperature of the first stage to drop to the second stage is kept at 25 minutes, and the time for the temperature of the second stage to drop to the third stage is kept at 23 minutes;

Then it is quenched at a quenching temperature of 850°C, a holding time of 6 minutes, and then quenched to room temperature to obtain a heat-treated plate for thermoformed parts.

Furthermore, high-pressure water phosphorus removal equipment is located between the online heating equipment and the rolling mill.

Embodiment three:

A thermal processing process for 1800 MPa high-strength steel mixed crystal, including the following steps:

S1. Mix the raw materials and pour them into the furnace for smelting, and pour the melted raw materials into the refining furnace for refining; during refining, inject a mixed gas of argon and oxygen to perform decarburization, and blow in high-pressure gas to drive the molten iron Flow to float impurities to the upper side, and take samples for testing to confirm that the ingredients are qualified;

S2. Use the continuous steel casting method to pour the molten steel into the mold so that it solidifies into a strip-shaped cast slab;

S3. Use the cutting equipment to cut the solidified cast billet into segments to become segmented steel billets. The length of the cut billets is 5-6 meters;

S4. The segmented steel billet is heated through the heating furnace. The heated steel billet is dephosphorized with high-pressure water to remove the oxide layer; specifically: under the action of erosion, peeling, and thermal explosion effects of the high-pressure water jet, the surface of the steel billet is The scales detach;

The heated segmental billet is hot-rolled through the rolling mill. After multiple rolling, the hot-rolled plate is prepared. During the multiple rolling process, the slab is heated, maintained and removed by online heating equipment for each 5 rolling passes. For phosphorus operation, the online heating equipment includes a conveyor roller 1 for conveying slabs, and the conveyor roller 1 is provided with multiple sets of induction heating furnaces 2 and holding furnaces 3 that are arranged crosswise in sequence. The conveyor roller 1 corresponds to the induction heating furnace 2. It is set up hollow so that the induction heating furnace 2 can heat the slab. The heating temperature of the steel billet by the induction heating furnace is 1400°C and the heating time is 60 minutes; the insulation temperature of the steel billet by the holding furnace is 1300°C and the insulation time is 120 minutes. Each round of rolling The temperature of the steel billet before processing is not lower than 900℃;

After the hot rolling is completed, it is sprayed with water to cool down;

S5. Cold-roll the hot-rolled plate to obtain a cold-rolled plate;

S6. After the cold-rolled plate is continuously annealed, the annealing is divided into three stages. The first stage annealing temperature is 850°C, and the annealing holding time is 5 minutes; the second stage annealing temperature is 650°C, and the holding time is 3 minutes; the third stage The stage is room temperature; and the time for the temperature of the first stage to drop to the second stage is kept at 30 minutes, and the time for the temperature of the second stage to drop to the third stage is kept at 25 minutes;

Then it is quenched at a quenching temperature of 900°C and a holding time of 8 minutes, and then quenched to room temperature to obtain a heat-treated plate for thermoformed parts.

Furthermore, high-pressure water phosphorus removal equipment is located between the online heating equipment and the rolling mill.

Under the above conditions, the tests of Example 1, Example 2 and Example 3 were respectively carried out, and heat-treated plates of the same size were prepared. The three heat-treated plates were tested and it was found that the tensile strength of the three heat-treated plates was greater than 610Mpa; The yield strength is greater than 350 MPa.

The present invention can increase the heating speed and heating effect of the steel billet during hot rolling by alternately setting the induction heating furnace 2 and the holding furnace 3, and adopts new heating and heat preservation methods and process parameters to greatly reduce the temperature difference between the inside and outside of the steel billet, thereby avoiding Cracks appear during hot rolling, and the amount of deformation can be increased at the same time, which can meet the needs for large plastic deformation of high-strength steel mixed crystals.

The undisclosed parts of the present invention are all existing technologies, and their specific structures, materials and working principles will not be described in detail. Although the embodiments of the present invention have been shown and described, those of ordinary skill in the art will understand that various changes, modifications, and substitutions can be made to these embodiments without departing from the principles and spirit of the invention. and modifications, the scope of the invention is defined by the appended claims and their equivalents.

Claims (6)

1. A thermal processing process for 1800 MPa high-strength steel mixed crystal, which is characterized by including the following steps: S1. Mix the raw materials and pour them into the furnace for smelting, and pour the melted raw materials into the refining furnace for refining; S2. Use the continuous steel casting method to pour the molten steel into the mold so that it solidifies into a strip-shaped cast slab; S3. Cut the solidified billet into segments through cutting equipment to become segmented steel billets; S4. Heat the segmented steel billet through the heating furnace, and hot-roll the heated segmented steel billet through the rolling mill. After multiple rollings, a hot-rolled plate is prepared. After the hot rolling is completed, it is sprayed with water to cool down; S5. Cold-roll the hot-rolled plate to obtain a cold-rolled plate; S6. After the cold-rolled plate is continuously annealed, it is then quenched to obtain a heat-treated plate for hot-formed parts. 2. The large-deformation thermal processing technology for solving mixed crystals of 1800 MPa high-strength steel according to claim 1, characterized in that: during refining in S1, a mixed gas of argon and oxygen is injected to perform decarburization, and High-pressure gas is blown in to drive the molten iron to flow, causing impurities to float to the upper side, and samples are taken for testing to confirm that the composition is qualified. 3. The large deformation thermal processing technology for solving mixed crystals of 1800 MPa high-strength steel according to claim 1, characterized in that: in S3, the length of the cut steel billet is 5-6 meters. 4. The large-deformation thermal processing technology for solving mixed crystals of 1800 MPa high-strength steel according to claim 1, characterized in that: in S4, the heated steel billet is dephosphorized with high-pressure water to remove the oxide layer; specifically: : Under the action of erosion, peeling and thermal explosion effects of high-pressure water jet, the scales on the surface of the steel billet are detached. 5. The large-deformation thermal processing technology for solving mixed crystals of 1800 MPa high-strength steel according to claim 4, characterized in that: in S4, during the multiple rolling processes, 3-5 passes of each rolling pass through the online The heating equipment performs heating, insulation and phosphorus removal operations on the slab. The online heating equipment includes a conveyor roller for conveying the slab, and the conveyor roller is provided with multiple sets of induction heating furnaces and heat preservation furnaces arranged crosswise in sequence. The parts corresponding to the rollers and the induction heating furnace are hollow, so that the induction heating furnace can heat the slab. 6. The large deformation thermal processing technology for solving mixed crystals of 1800 MPa high-strength steel according to claim 5, characterized in that: the high-pressure water phosphorus removal equipment is located between the online heating equipment and the rolling mill.