Production process for warm charging of high-quality special steel continuous casting billet

Abstract

The invention relates to the technical field of steel and iron smelting, in particular to a high-quality special steel continuous casting billet warm charging production process which comprises the steps of converter smelting, external refining, continuous casting, casting billet treatment, rolling and cooling. Wherein the casting blank treatment adopts a process of combining hot feeding and warm charging. According to the production process for warm charging of the high-quality special steel continuous casting billets, the mode that the hot delivery process and the warm charging process are combined is adopted, the charging temperature range is enlarged, the charging freedom degree and operation efficiency are improved, energy consumption is finally saved, the requirement for energy saving can be met, the quality of the core and the surface of steel can be improved, and the production cost is reduced. And the production efficiency and the quality of high-quality special steel are improved.

Description

Technical Field

[0001] The invention relates to the technical field of steel smelting, and in particular to a production process for warm charging of high-quality steel continuous casting billets. Background Art

[0002] Continuous casting hot delivery and hot loading can not only achieve better economic benefits, but also improve production efficiency. However, when the continuous casting and bar workshops are connected, production mismatches often occur. Only part of the hot delivery can be accepted, and the remaining part must be put into the pit for slow cooling. The slow cooling time is more than 48 hours before the pit production can be started again. This causes frequent changes in production varieties, making production organization difficult, time-consuming, and labor-intensive, and increasing production costs.

[0003] Advantages and disadvantages of common continuous casting billet charging methods: The hot delivery temperature range of continuous casting billet direct rolling (CC-DR) and continuous casting billet direct hot rolling (CC-HDR) is above Ar3, which is suitable for high-speed continuous casting and needs to be equipped with special temperature compensation equipment. Only a small amount of trace elements are precipitated and redissolved; the hot delivery temperature range of continuous casting direct hot charging rolling (CC-DHCR) is Ar3-Ar1. At this time, the billet is in the two-phase region, with both original coarse austenite grains and refined austenite grains after phase transformation. In this way, the billet after heating has a mixed crystal structure. For some low-alloy steels and medium and high carbon steels, especially electric furnace steels, due to the high nitrogen content , surface cracks are formed due to the precipitation of AlN, CN, etc., and the continuous casting hot delivery and hot charging process line with good thermal insulation effect belongs to this type; the hot delivery temperature range of continuous casting hot charging and rolling (CC-HCR) is Ar1-400℃, and the microstructure of the ingot is basically the same as that of the conventional cold charging furnace ingot, but when the production organization is not well controlled, the temperature is too high and mixed crystals appear; the hot delivery temperature range of continuous casting cold charging and rolling (CC-CCR) is below 400℃. When the temperature is less than 400℃, it is generally no longer called hot charging. The ingot is put into the furnace in a cold state. For products with high alloy elements, low thermal conductivity and large cross-sectional size, large thermal stress is generated after entering the furnace, which may cause internal cracking.

[0004] At present, there are two common ways to charge high-quality steel, one is hot delivery at above 400℃, and the other is slow cooling followed by cold charging. From the perspective of energy saving, the higher the temperature of hot delivery, the better; from the perspective of quality and production, high-temperature hot delivery or even charging in the two-phase zone is prone to mixed crystals; from the perspective of production organization, slow cooling requires a large number of slow cooling pits, which makes production organization difficult and has poor continuity, which is not conducive to large-scale production organization.

[0005] Based on this, developing a furnace loading method suitable for high-quality steel to efficiently smelt and obtain high-quality steel is a technical problem that needs to be solved urgently. Summary of the invention

[0006] The purpose of the present invention is to provide a production process for warm charging of high-quality special steel continuous casting billets, which can not only save energy consumption but also stably and efficiently smelt and obtain high-quality special steel.

[0007] In order to achieve the above-mentioned purpose, the present invention provides a production process for warm charging of high-quality steel continuous casting billets, the production process comprising: converter smelting - refining outside the furnace - continuous casting - billet processing - rolling - cooling; wherein, the billet processing adopts a process combining hot delivery and warm charging.

[0008] Preferably, the warm loading conditions include: a temperature range of 200-400°C.

[0009] Preferably, the conditions for the hot delivery include: temperature ≥ 400°C.

[0010] Preferably, before the warm loading, the continuous casting billets that do not meet the hot delivery conditions are placed in a holding pit, and after the hot delivered continuous casting billets are rolled, the continuous casting billets in the holding pit are warm loaded and rolled.

[0011] Preferably, the production process is suitable for high-quality steel.

[0012] In the above technical scheme, the production process temperature of the warm charging of the high-quality steel continuous casting billet of the present invention is 200-400°C. The continuous casting billet that cannot be hot-delivered adopts the warm charging process. At this time, the phase change of the continuous casting billet has been completed, and the internal and external temperatures are uniform, which can not only ensure a certain plasticity, but also reduce the temperature difference between the furnace temperature and the steel temperature, avoiding thermal stress cracking caused by excessive temperature difference.

[0013] In addition, the production process for warm charging of high-quality steel continuous casting billets of the present invention adopts a combination of hot delivery technology and warm charging technology, which increases the temperature range of charging, improves the freedom of charging and operating efficiency, and ultimately saves energy consumption. It can not only meet the requirements of energy saving, but also improve the quality of the core and surface of the steel grade, thereby improving production efficiency and the quality of high-quality steel.

[0014] Other features and advantages of the present invention will be described in detail in the following detailed description. DETAILED DESCRIPTION

[0015] The specific embodiments of the present invention are described in detail below. It should be understood that the specific embodiments described herein are only used to illustrate and explain the present invention, and are not used to limit the present invention.

[0016] The present invention provides a production process for warm charging of high-quality steel continuous casting billets, the production process comprising: converter smelting - refining outside the furnace - continuous casting - billet treatment - rolling - cooling; wherein the billet treatment adopts a process combining hot delivery and warm charging.

[0017] The production process temperature of the high-quality steel continuous casting billet warm charging of the present invention is 200-400°C. The continuous casting billet that cannot be hot-transported adopts the warm charging process. At this time, the phase change of the continuous casting billet has been completed, and the internal and external temperatures are uniform, which can not only ensure a certain plasticity, but also reduce the temperature difference between the furnace temperature and the steel temperature, avoiding thermal stress cracking caused by excessive temperature difference.

[0018] In addition, the production process for warm charging of high-quality steel continuous casting billets of the present invention adopts a combination of hot delivery technology and warm charging technology, which increases the temperature range of charging, improves the freedom of charging and operating efficiency, and ultimately saves energy consumption. It can not only meet the requirements of energy saving, but also improve the quality of the core and surface of the steel grade, thereby improving production efficiency and the quality of high-quality steel.

[0019] In a preferred embodiment of the present invention, the warm loading conditions include: a temperature range of 200-400°C.

[0020] In a preferred embodiment of the present invention, the conditions for heat transport include: temperature ≥ 400°C.

[0021] In a preferred embodiment of the present invention, before the warm loading, the continuous casting billets that do not meet the hot delivery conditions are placed in a holding pit, and after the hot delivered continuous casting billets are rolled, the continuous casting billets in the holding pit are warm loaded and rolled.

[0022] In a preferred embodiment of the present invention, the production process is suitable for steel types with high requirements on core quality and surface quality, such as high-quality steel.

[0023] The present invention will be described in detail below by way of examples. In the following examples, all drugs not specifically specified are conventional commercial products.

[0024] Example 1

[0025] The production process of warm charging of high-quality steel continuous casting billets using the present invention adopts 600 round billets to open billets and continuously roll large-size bars to produce 45 steel and 42CrMoA respectively, and the steel grades are subjected to flaw detection. The production standards and flaw detection results are shown in Table 1.

[0026] Table 1

[0027] Steel Type Specification range standard Number of flaw detection Qualified number of Pass rate 45 steel 160-230 GB / T4162-2018 Grade B 80 80 100％ 42CrMoA 170-310 GB / T4162-2018 Grade B 30 30 100％

[0028] It can be seen from the content of Table 1 that after adopting the production process of warm charging of high-quality steel continuous casting billets of the present invention, the flaw detection pass rate of the bars can still be guaranteed, and the amount of gas used is reduced from 491.31 cubic meters per ton to 472.65 cubic meters per ton compared with the original production process, which is a reduction of 19.66 cubic meters per ton. It can be seen that the production process of warm charging of high-quality steel continuous casting billets of the present invention saves energy consumption, can meet the requirements of energy saving, and can meet the quality of the core and surface of the steel grade, thereby improving production efficiency and the quality of high-quality steel.

[0029] The preferred embodiments of the present invention are described in detail above. However, the present invention is not limited to the specific details in the above embodiments. Within the technical concept of the present invention, a variety of simple modifications can be made to the technical solution of the present invention, and these simple modifications all belong to the protection scope of the present invention.

[0030] It should also be noted that the various specific technical features described in the above specific embodiments can be combined in any suitable manner without contradiction. In order to avoid unnecessary repetition, the present invention will not further describe various possible combinations.

[0031] In addition, various embodiments of the present invention may be arbitrarily combined, and as long as they do not violate the concept of the present invention, they should also be regarded as the contents disclosed by the present invention.

Claims

1. A production process for warm charging of high-quality steel continuous casting billets, characterized in that: The production process includes: converter smelting - refining outside the furnace - continuous casting - ingot processing - rolling - cooling; wherein, The ingot treatment adopts a process combining hot delivery and warm loading.

2. The production process according to claim 1, characterized in that: The conditions for warm loading include: a temperature range of 200-400°C.

3. The production process according to claim 1 or 2, characterized in that: The conditions for hot delivery include: temperature ≥ 400°C.

4. The production process according to any one of claims 1 to 3, characterized in that: Before the warm loading, the continuous casting billets that do not meet the hot delivery conditions are placed in a holding pit, and after the hot delivered continuous casting billets are rolled, the continuous casting billets in the holding pit are warm loaded and rolled.

5. The production process according to any one of claims 1 to 4, characterized in that: The production process is suitable for high-quality steel.