1. Technical Characteristics of Alloy Steel Billet Caster Process
1.1 Model Selection
Under normal circumstances, the devices produced by the alloy steel billet caster process are used in important parts of mechanical production. From this point of view, the processing technology of alloy steel grades is generally more complicated, regardless of the surface quality. Or internal quality, there are relatively high requirements. It is also important to note that there are many kinds of components of alloy steel, and the characteristics of different components themselves are very different and different. In the process of production and manufacturing, it is easy to have problems. At the same time, , There are also problems such as poor thermal conductivity. These characteristics are the basis for determining the use and production of alloy steel continuous casting process, resulting in higher requirements for corresponding machinery and equipment in the actual production process.
From the perspective of the models currently used, vertical, curved, or large radius arc continuous casters are mainly used. When conducting large section bloom, vertical or vertical curved continuous casters are generally used. However, the cost of such continuous casters is relatively high, which is relatively rare in practical applications. In most cases, an arc continuous casting machine is basically used for the corresponding production.
1.2 Main Design Points of Billet Caster Process
(1) Requirements for molten steel supply: In the actual billet caster process, we must pay attention to the relevant measures for molten steel supply to prevent some unnecessary problems during the production and manufacturing process. Next, we will make some analysis:
① The composition of molten steel shall be strictly controlled. During the use of molten steel, it is necessary to use relatively clean molten steel, in which the impurity content must be well controlled to avoid some quality problems. For example, bearing molten steel requires high purity of molten steel. If the purity of molten steel is not up to standard, it is easy cause some quality problems;
② Molten steel with appropriate temperature shall be used. In the billet caster process and manufacturing, the use of low superheat molten steel can prevent the occurrence of similar quality defects such as central porosity;
③ Pay attention to the temperature difference before and after casting. In the process of actual teaching, corresponding thermal insulation and other protective measures must be taken to prevent some quality problems caused by excessive temperature differences before and after casting.
(2) Prevention of secondary pollution of molten steel: in the process of casting, the quality of molten steel must be guaranteed. In addition, attention should be paid to preventing secondary pollution of molten steel. This is also a very important part, so corresponding protective measures must be taken:
① In the billet caster process, it is necessary to protect the whole process to prevent oxidation of molten steel. Generally, in this case, a sealing device combining ladle steel flow protective sleeve and neon gas can be used to carry out corresponding protection work. In the process of casting, the submerged nozzle shall be used to protect the casting quality;
② Large capacity deep tundish shall be used. In this case, it is necessary to ensure that the temperature of molten steel in the tank is evenly distributed, and increase the residence time of molten steel;
③ Materials in tundish shall be selected properly. Generally, in the process of work, it will be in a high temperature for a long time. At this time, there is a very high requirement for the materials used in the tundish;
④ Suitable devices shall be used to lift the tundish.
2. Key Points of Process Design for Billet Continuous Casting Workshop
2.1 Cooling of Casting Blank
At present, the main reason why the continuous casting of some special steels can not replace the mold casting is that there is segregation in the center of the casting billet. In order to avoid component segregation, there are two possibilities: first, when the crystallization process takes a long time, it needs to be slowly cooled, so that the elements in the steel have sufficient time to diffuse, so as to achieve balance; The other is extreme cooling, and complete crystallization is carried out under the condition of restraining precipitation. Therefore, the cooling system of special steel continuous casting usually has two ways:
2.1.1 Forced Cooling Mode
The cooling water pressure of the crystallizer can reach 1.0MPa, and the flow rate of the water gap can reach 16m/s; The secondary cooling water is sprayed and cooled by means of high pressure, and the water supply pressure can reach more than 1.2MPa. The main principle is to cool the slab rapidly, and the elements in the front of solid and liquid solidification cannot be diffused in time, so that the solidification fabric without component segregation and with uniform composition can be obtained. The main components of the crystal structure are developed columnar crystals in the interior and compact equiaxed crystals on the surface of the slab. Due to the rapid crystallization of dendrites, the molten steel between dendrites does not have a long time to feed and flow. Therefore, the center of the slab is relatively loose and there is no large central shrinkage cavity.
2.1.2 Weak Cooling Mode
The temperature difference between the inlet and outlet of the crystallizer is large, so the conventional cooling mode is required; The secondary cooling water is cooled by air-water atomization. In this way, the solidification thermal stress is low, the temperature gradient at the front of solidification is small, the slab surface temperature is high, the casting speed is low, the specific water volume is small, and cracks are not easy to appear. The temperature of molten steel at the front of solid and liquid solidification is basically constant, which inhibits the growth of columnar crystals, so that the elements in the steel can fully diffuse and reach the solidification equilibrium state.
2.2 Key Points of Continuous Casting Quality Design
In order to further ensure the quality of continuous casting production, in addition to the above two aspects, we also need to take corresponding assurance measures. Next, we will make a certain analysis of them:
① In order to effectively ensure the surface and internal quality of the slab, we must use appropriate mixing devices for corresponding operations;
② The current science and technology should be fully combined to achieve automatic operation and simplify the operation process to a certain extent;
③ The reasonable cooling design scheme should be adopted according to the actual conditions to ensure that the billet can also maintain a good state during the cooling process;
④ Appropriate adjustment technology and corresponding vibration technology shall be adopted for the corresponding adjustment;
⑤ In order to avoid cracks in the production process, relevant technologies need to be used for timely rectification, such as large arc radius and continuous straightening technology. In the overall design process, its quality also needs to be comprehensively tested. Finally, the continuous casting quality is guaranteed as a whole.
It is important to analyze the key points of the billet caster process, which can improve the efficiency of continuous casting as a whole. In the process of design, the technology of the continuous casting workshop needs to be analyzed as a whole. Then, the model selection and design architecture optimization are carried out according to its technical characteristics. Finally, the overall design points are analyzed scientifically and reasonably, so as to improve the quality of process design.