Continuous casting method of continuous-cast round billets

Abstract

The invention discloses a continuous casting method of continuous-cast round billets. The method comprises the steps of 1) obtaining high-purity molten steel through steel-making; 2) pouring the obtained molten steel into a tundish under large-tundish long-nozzle argon blowing protection, controlling the degree of superheat of the molten steel inside the tundish to be 15-30 DEG C; 3) pouring the molten steel into a crystallizer through a tundish integrated type submerged nozzle, controlling the depth of the a crystallizer submerged nozzle inserted into the surface of the molten steel to be 100-120 mm; (4) perform constant-speed continuous casting, control the casting speed to be 0.16-0.22 m / min for different kinds of steel; 5) utilizing an air-water atomizing cooling mode in a secondary cooling area at a specific water flow rate of 0.12-0.22 L / kg; 6) performing dynamic soft reduction through a withdrawal and straightening machine to obtain the continuous-cast round billets. The continuous casting method of the continuous-cast round billets effectively reduces the temperature gradient of molten steel from a billet shell to a casting core and the degree of superheat of the molten steel in the center, improves the proportion of isometric crystal of the cast billets, enhances the structural density of the cast billets and significantly improves the effects of center porosity, center segregation and contraction of large continuous-cast round billets.

Description

Technical field [0001] The invention belongs to the technical field of metallurgy, and specifically relates to a continuous casting method for continuous casting round billets. Background technique [0002] The continuous casting round billet with a diameter of 800mm can be used to produce nuclear flashlights, wind power ring parts, and key shaft parts for automobiles, ships, and machinery. Compared with large steel ingots produced by casting methods, casting billets produced by continuous casting process The ratio of height to diameter is large, it is difficult to realize the axis feeding of the slab, and it is easy to cause shrinkage and looseness in the center of the continuous casting slab, resulting in failure to heal defects in the subsequent forging or rolling process, and the application areas of the products are more complicated. There are not only requirements for strength, impact resistance, corrosion resistance, and wear resistance, but also UT, magnetic powder and ot...

AI Technical Summary

Problems solved by technology

[0002] Continuous casting round billets with a diameter of 800mm can be used to produce nuclear power tubes, wind power rings, and key shaft parts for automobiles, ships, and machinery. Compared with large steel ingots produced by casting, the billets produced by continuous casting technology Its high aspect ratio makes it difficult to achieve axial feeding of the slab, and it is easy to cause shrinkage and porosity in the center of the continuous casting slab, resulting in unhealed defects in the subsequent forging or rolling process. Not only have the requirements for strength, impact resistance, corrosion resistance, wear resistance, but also meet the requirements of UT, magnetic particle and other flaw detection; large-section continuous casting round billets are often due to poor purity of molten steel, unreasonable cooling intensity and uniformity, Improper process parameters, etc., can easily lead to problems such as high content of inclusions, poor composition and structure uniformity, and it is difficult to meet product performance requirements

[0003] Due to the wide variety of special steels and frequent changes in casting speed, the control accuracy and sensitivity of regulating valves and testing instruments, etc., the effect of controlling the quality of continuous casting round billets in the prior art is not ideal.

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