WO2022099680A1 - Converter and continuously-cast small billet-based production method for npr rock bolt or anchor cable novel material - Google Patents

Abstract

A converter and continuously-cast small billet-based production method for an NPR rock bolt or anchor cable novel material. Elements in an NPR rock bolt or anchor cable respectively comprise in percentage by mass: C: 0.4-0.9%, Mn: 14-22%, Al: 0-4%, Cr: 0.1-10%, Si: 0.1-3%, an NPR crystal: 0-2%, Ca: 0.01-0.25%, Cu: ≤0.09%, Ni: ≤0.09%, S: ≤0.001%, P: ≤0.001%, and the remainder being Fe and inevitable impurity elements. The production method comprises the following processes: a converter steelmaking process; an LF refining process; a VD refining process; a small billet continuous casting process; a heating process of steel rolling; and a rolling process of steel rolling. The production method effectively solves the problem in the prior art that an NPR rock bolt or anchor cable steel material is high in production cost and low in production efficiency.

Description

NPR anchor rod or anchor cable new material converter and production method of continuous casting billet technical field

The invention relates to the technical field of supporting materials for rock mechanics, in particular to a new material converter for NPR bolts or anchor cables and a production method for continuous casting billets.

Background technique

With the increase of energy demand for economic construction, the safety of coal production has become one of the prominent problems restricting the development of coal mines in my country. my country's coal resource reserves have relatively poor geological mining conditions, deep burial, and poor coal seam stability. One-third of the geological structure is complex or extremely complex. Resources are increasingly depleted, and domestic and foreign mines have successively entered the state of deep mining.

The support methods based on traditional materials such as traditional bolts, anchor cables, and U-shaped steel retractable brackets are widely used in coal seam roadways at home and abroad. However, these bolts belong to traditional Poisson's ratio materials, that is, plastic hardening materials. It has poor performance such as strength, elongation and scalability, and can no longer adapt to the nonlinear large deformation and failure characteristics of the surrounding rock in the deep roadway. Under the action of the impact load, it reaches its yield strength instantly, and the bolt fails and loses its bearing capacity. The protective ability of the roadway will be damaged, resulting in repeated repairs of the roadway, distortion of the steel frame, and cracking of the poured concrete. Therefore, with the increasing depth of roadway/tunnel, it also poses a severe challenge to the research of deep surrounding rock supporting materials, and it is urgent to develop new supporting materials, such as NPR steel materials.

The production method of NPR bolt or anchor cable steel material disclosed in the prior art is generally by adopting intermediate frequency smelting, mold casting process route to carry out the production of NPR bolt or anchor cable new material, but the production method in the prior art exists. Low yield, high production cost and low production efficiency. Therefore, the development of a large-scale, low-cost and continuous production process for new NPR bolts or new anchor cables has become an urgent problem to be solved in the steel material industry.

SUMMARY OF THE INVENTION

The embodiment of the present invention provides a NPR bolt or anchor cable new material converter and a production method for continuous casting billet, so as to solve the problem of high production cost and high production efficiency in the prior art production method of NPR bolt or anchor cable steel material low problem.

In order to achieve the above object, the invention provides a kind of NPR anchor rod or anchor cable new material converter and the production method of continuous casting billet, the element of described NPR anchor rod or anchor cable and its mass percentage are respectively C: 0.4～0.9%, Mn: 14～22%, Al: 0～4%, Cr: 0.1～10%, Si: 0.1～3%, NPR crystal 0～2%, Ca: 0.01～0.25%, Cu: ≤ 0.09%, Ni: ≤ 0.09%, S: ≤ 0.001%, P: ≤ 0.001%, the rest are Fe and inevitable impurity elements, the production method includes the following steps:

Converter steelmaking process: add molten iron and scrap steel that meet the production requirements of steel grades into the converter, and use top-bottom combined blowing mode for smelting, adding slag-forming agent during the blowing process, and stop blowing when the composition and temperature of molten steel at the end of the converter hits , Deoxidation of molten steel is carried out during the tapping process;

LF refining process: By monitoring the composition of molten steel in real time, various alloys are added with the composition of NPR anchor rod or anchor cable as the target composition, and the composition of molten steel is adjusted and stably controlled to the target range. During the refining process, it is removed by blowing argon from the bottom of the ladle. Inclusions in molten steel, adding ≤2% NPR crystals during refining;

VD refining process: firstly, the molten steel is fed with calcium. During the VD refining process, a high degree of vacuum is maintained, and a strong degassing mode is used; After emptying, let the ladle stand for weak stirring;

Billet continuous casting process: inject the molten steel refined by VD into the tundish, and then distribute the molten steel to each mold of the continuous casting machine to make it solidify and crystallize. The mold uses electromagnetic stirring and pulls out the steel billet in the mold , the drawing speed is constant; the water is automatically distributed in the secondary cooling process, and the molten steel is protected by the whole process of pouring technology during the continuous casting process to prevent the molten steel from oxidizing and inhaling, and finally the molten steel is continuously cast into billets;

Heating process of steel rolling: transfer the billet produced by the billet continuous casting process into the heating furnace for heating, and the billet is released after heating;

Rolling process of steel rolling: The billet after heating and descaling by high-pressure water is transferred to the rolling production line for rapid rolling, and the opening temperature, finishing temperature and rolling speed are controlled, and the billet is naturally cooled to room temperature after hot rolling. .

Further, the steel grade composition needs to be narrowly controlled in the smelting process, and in the converter steelmaking process and the LF refining process, the carbon content of the molten steel is controlled at C target ±0.03%.

Further, in the LF refining process, a dynamic bottom blowing argon gas mode is adopted throughout the whole process, and the gas supply flow rate is 5-35 NL/(min·t), and electrolytic aluminum, ferromanganese, ferrosilicon, and ferrochromium alloys are added in the LF refining process. , and adjust to the target composition.

Further, the degree of vacuum in the VD refining process should be maintained at 57-77Pa; the flow rate of the bottom blowing unit in the strong degassing mode is 0.3-8NL/(min·t).

Further, in the billet continuous casting process, the electromagnetic stirring frequency of the crystallizer is set to 5-20Hz, the current intensity is 200-400A; the second cooling dynamic water distribution is adopted, the casting speed is constant at 0.3-2.5m/min, and the specific water volume is 0.3-2.5m/min. 0.5～1.3L/kg steel.

Further, in the continuous casting process of the billet continuous casting process, the section of the billet is: 152mm*152mm.

By adopting the NPR anchor rod or anchor cable new material converter and the production method of continuous casting billet of the present invention, the billet continuous casting process has high production efficiency and high yield; The characteristics are matched and can be produced by continuous casting process. The invention overcomes the problems of low yield, high production cost, low production efficiency and the like in the production technology of NPR anchor rod or new anchor cable material using intermediate frequency smelting and mold casting process routes in the prior art. Preliminary calculation of its production cost is about 1500 yuan/ton steel lower than that of medium frequency mold casting, which can greatly reduce production costs.

Description of drawings

Fig. 1 is the schematic flow chart of the production method of the NPR bolt or the new material converter of the anchor cable and the continuous casting billet of the embodiment of the present invention;

FIG. 2 is a schematic diagram of the stress-strain curve of the NPR bolt or the new material of the anchor cable prepared by the NPR bolt or anchor cable new material converter and the production method of the continuous casting billet according to the embodiment of the present invention.

Detailed ways

The present invention will be described in further detail below with reference to the accompanying drawings and specific embodiments, but it is not intended to limit the present invention.

Referring to FIG. 1 , according to an embodiment of the present invention, a NPR bolt or cable new material converter and a production method for continuous casting billets are provided, the elements of the NPR bolt or cable and the quality thereof are 100%. The contents are C: 0.4-0.9%, Mn: 14-22%, Al: 0-4%, Cr: 0.1-10%, Si: 0.1-3%, NPR crystal 0-2%, Ca: 0.01- 0.25%, Cu: ≤0.09%, Ni: ≤0.09%, S: ≤0.001%, P: ≤0.001%, the rest are Fe and inevitable impurity elements, the production method includes the following steps:

Converter steelmaking process S1: Add molten iron and scrap steel that meet the production requirements of steel grades into the converter, use top-bottom combined blowing mode for smelting, add slag-forming agent during the blowing process, and stop blowing when the final point of the converter hits the molten steel composition and temperature smelting, deoxidation of molten steel in the process of tapping;

LF refining process S2: By monitoring the composition of molten steel in real time, various alloys are added with the composition of NPR anchor rod or anchor cable as the target composition, and the composition of molten steel is adjusted and stably controlled to the target range. During the refining process, argon gas is blown from the bottom of the ladle. Remove inclusions in molten steel, and add ≤2% NPR crystals during refining;

VD refining process S3: firstly, the molten steel is calcium fed. During the VD refining process, a high degree of vacuum is maintained, and a strong degassing mode is adopted; After the air is broken, the ladle is left to stand for weak stirring;

Billet continuous casting process S4: The molten steel refined by VD is injected into the tundish, and then the molten steel is distributed to each mold of the continuous casting machine to make it solidify and crystallize. The mold adopts electromagnetic stirring and pulls the steel billet in the mold. In the process of continuous casting, the whole process of protection pouring technology is used to prevent the oxidation and suction of the molten steel, and finally the molten steel is continuously cast into billets;

Steel rolling heating process S5: the billet produced in the billet continuous casting process is transferred into a heating furnace for heating, and the billet is released after heating;

Rolling process S6 of steel rolling: transfer the heated and descaled billet to the rolling production line for rapid rolling, control the starting rolling temperature, final rolling temperature and rolling speed, and naturally cool the billet to a temperature after hot rolling treatment. room temperature.

By adopting the NPR anchor rod or anchor cable new material converter and the production method of continuous casting billet of the present invention, the billet continuous casting process has high production efficiency and high yield; The characteristics are matched and can be produced by continuous casting process. The invention overcomes the problems of low yield, high production cost, low production efficiency and the like in the production technology of NPR anchor rod or new anchor cable material using intermediate frequency smelting and mold casting process routes in the prior art. Preliminary calculation of its production cost is about 1500 yuan / ton of steel lower than that of intermediate frequency mold casting, which can greatly reduce production costs. Not only that, the NPR anchor rod or anchor cable new material converter and the production method of continuous casting billet of the present invention also have the following advantages compared with the ordinary continuous casting bloom process: 1) The billet continuous casting can be very large. To a certain extent, the bloom segregation caused by the high Mn content in the molten steel is avoided; 2) The aluminum content in the molten steel is high. Compared with the bloom process, after adding VD degassing, the amount of slag during continuous casting of the billet is less, so the slag 3) The cut section of the billet is smaller, it is easier to roll, and the difference between the internal and external properties of the bloom can be avoided. 4) The billet continuous casting avoids the blooming process of the bloom and improves the production efficiency. Compared with the continuous casting of the bloom, the cost per ton of steel is about 200-300 yuan.

The components of the new material of the NPR anchor rod or anchor cable to be produced in the present invention are explained:

C: To ensure that the new material of NPR anchor rod or anchor cable has a sufficiently high strength during the plastic deformation process, select 0.4-0.9% to keep its plasticity and toughness at the original level, and ensure the deterioration of impact performance.

Mn: Mainly austenitization forming element, can reduce stacking fault energy, it is also a good deoxidizer and desulfurizer, containing a certain amount of manganese can eliminate or weaken the brittleness caused by sulfur.

Al: Containing a certain amount of Al can improve the delayed cracking performance of the material during the service process, and at the same time improve the processing performance of the steel.

Cr: Chromium can improve the strength and hardness of NPR bolts or new anchor cables, reduce elongation and section shrinkage, and contain a certain amount of chromium, which can improve the strength of the material and improve the corrosion resistance at the same time.

Si: It does not form carbides in steel, but exists in ferrite or austenite in the form of solid solution, which significantly increases the elastic limit, yield strength and yield ratio of steel, so the content is low.

NPR crystal: A certain amount of NPR crystal can improve the plastic transfer mode of the material in the process of plastic deformation and improve the strain concentration phenomenon when the material is fractured at a rapid rate, thereby improving its ability to absorb deformation energy.

Ca: A certain amount of calcium can desulfurize and deoxidize to refine grains, change the composition, quantity and shape of non-metallic inclusions, improve the fluidity of molten steel, as well as the hardness and lasting strength of steel.

Cu: The addition of a trace amount of copper can improve the strength and yield ratio of steel.

Ni: Nickel can improve the strength, toughness and hardenability of steel, and a certain amount of nickel can improve the strength and toughness.

P, S, H, N: As harmful elements, the lower the content, the better. If the content of S is too high, a large number of MnS inclusions will be formed, which will reduce the ductility and toughness of the steel. Therefore, the lower the content, the better. Therefore, the range of S is selected to be ≤ 0.001%; The impact performance is greatly reduced, so the lower the content, the better, so the range of P is selected to be ≦0.001%. A single wire of NPR anchor cable with a diameter of 7.2mm prepared by the production method of NPR anchor rod or anchor cable new material converter and continuous casting billet has a yield strength of about 880MPa and a maximum elongation rate of about 32%. , the data is shown in Figure 2.

Preferably, in the above production method, the steel grade composition needs to be narrowly controlled in the smelting process, and in the converter steelmaking process and the LF refining process, the carbon content of the molten steel is controlled at C target ±0.03%. The purpose of controlling the carbon content of molten steel is to avoid slab segregation caused by chemical composition deviation.

Preferably, in the LF refining process, a dynamic bottom blowing argon gas mode is adopted throughout the whole process, and the gas supply flow rate is 5-35 NL/(min·t), and electrolytic aluminum, ferromanganese, ferrosilicon, and ferrochromium are added in the LF refining process. , and adjust to the target composition.

Preferably, the degree of vacuum in the VD refining process should be maintained at 57-77Pa; the flow rate of the bottom blowing unit in the strong degassing mode is 0.3-8NL/(min·t).

Preferably, in the continuous casting process of the billet, in order to control the surface defects such as transverse cracks and corner cracks on the surface of the continuous casting billets, as well as defects such as core cracks, the electromagnetic stirring frequency of the mold is set to 5-20 Hz, and the current The strength is 200-400A; the second cooling is used for dynamic water distribution, the casting speed is constant at 0.3-2.5m/min, and the specific water volume is 0.5-1.3L/kg steel.

Preferably, in the continuous casting process of the billet continuous casting process, the section of the billet is: 152mm*152mm.

It should be noted that the terminology used herein is for the purpose of describing specific embodiments only, and is not intended to limit the exemplary embodiments according to the present application. As used herein, unless the context clearly dictates otherwise, the singular is intended to include the plural as well, furthermore, it is to be understood that when the terms "comprising" and/or "including" are used in this specification, it indicates that There are features, steps, acts, devices, components, and/or combinations thereof.

It should be noted that the terms "first", "second", etc. in the description and claims of the present application and the above drawings are used to distinguish similar objects, and are not necessarily used to describe a specific sequence or sequence. It is to be understood that data so used may be interchanged under appropriate circumstances so that the embodiments of the application described herein can be practiced in sequences other than those illustrated or described herein.

Of course, the above are preferred embodiments of the present invention. It should be pointed out that for those skilled in the art, without departing from the basic principle of the present invention, several improvements and modifications can also be made, and these improvements and modifications are also regarded as the protection scope of the present invention.

Claims (6)

1. A new material converter for NPR bolts or anchor cables and a production method for continuous casting billets. The elements of the NPR bolts or anchor cables and their mass percentages are respectively C: 0.4-0.9%, Mn: 14- 22%, Al: 0~4%, Cr: 0.1~10%, Si: 0.1~3%, NPR crystal 0~2%, Ca: 0.01~0.25%, Cu: ≤0.09%, Ni: ≤0.09%, S: ≤ 0.001%, P: ≤ 0.001%, and the rest are Fe and inevitable impurity elements, characterized in that the production method includes the following steps:

   Converter steelmaking process: add molten iron and scrap steel that meet the production requirements of steel grades into the converter, and use the top-bottom combined blowing mode for smelting, adding slag-forming agent during the blowing process, and stop blowing when the molten steel composition and temperature are hit at the end of the converter. , Deoxidation of molten steel is carried out during the tapping process;

   LF refining process: By monitoring the composition of molten steel in real time, various alloys are added with the composition of NPR anchor rod or anchor cable as the target composition, and the composition of molten steel is adjusted and stably controlled to the target range. During the refining process, it is removed by blowing argon from the bottom of the ladle. Inclusions in molten steel, adding ≤2% NPR crystals during refining;

   VD refining process: firstly, the molten steel is fed with calcium. During the VD refining process, a high degree of vacuum is maintained, and a strong degassing mode is used; After emptying, let the ladle stand for weak stirring;

   Billet continuous casting process: inject the molten steel refined by VD into the tundish, and then distribute the molten steel to each mold of the continuous casting machine to make it solidify and crystallize. The mold uses electromagnetic stirring and pulls out the steel billet in the mold , the drawing speed is constant; the water is automatically distributed in the secondary cooling process, and the molten steel is protected by the whole process of pouring technology during the continuous casting process to prevent the molten steel from oxidizing and inhaling, and finally the molten steel is continuously cast into billets;

   Heating process of steel rolling: transfer the billet produced by the billet continuous casting process into the heating furnace for heating, and the billet is released after heating;

   Rolling process of steel rolling: The billet after heating and descaling by high-pressure water is transferred to the rolling production line for rapid rolling, and the opening temperature, finishing temperature and rolling speed are controlled, and the billet is naturally cooled to room temperature after hot rolling. .
2. The production method according to claim 1, wherein the steel grade composition needs to be narrowly controlled in the smelting process, and in the converter steelmaking process and the LF refining process, the carbon content of the molten steel is controlled to be C Target ±0.03%.
3. The production method according to claim 1, characterized in that, in the LF refining process, a dynamic bottom blowing argon gas mode is adopted in the whole process, and the gas supply flow rate is 5-35NL/(min·t), and in the LF refining process, adding Electrolytic aluminum, ferromanganese, ferrosilicon, ferrochromium alloy, and adjusted to the target composition.
4. production method according to claim 1, is characterized in that, in described VD refining process, vacuum degree should be kept at 57-77Pa;

   The flow rate of the bottom blowing unit in the strong degassing mode is 0.3-8NL/(min·t).
5. The production method according to claim 1, characterized in that, in the billet continuous casting process, the frequency of electromagnetic stirring of the mold is set to 5-20 Hz, and the current intensity is 200-400 A;

   The second cooling dynamic water distribution is adopted, the casting speed is constant at 0.3~2.5m/min, and the specific water volume is 0.5~1.3L/kg steel.
6. The production method according to claim 1, wherein in the continuous casting process of the billet continuous casting process, the section of the billet is: 152mm*152mm.

Images