A kind of smelting method of ultra-low phosphorus steel

Abstract

The invention discloses a smelting method of ultra-low phosphorus steel. The smelting method comprises the following steps: (1) in-furnace molten iron: 4.0-4.6% of C, 0.35-0.75% of Si, 0.11-0.14% of P and 0.05-0.1% of Ti; (2) primary blowing: in carbon catching, the C accounts for 0.05-0.07%, the temperature is 1,600-1,640 DEG C, and the P content at the end point is less than or equal to 0.012%; (3) charging and supplementary blowing: the target temperature of supplementary blowing is 1,650-1,690 DEG C, a slagging material is added again for slagging, and the P content at the end point is less than or equal to 0.004%; and (4) tapping. According to the invention, the primary blowing is effectively combined with the supplementary blowing; through the ways such as supplementary blowing, bottom stirring during standing, deslagging and phosphorus removal and double reduction of rephosphorization amount during tapping, the best phosphorus removal effect is guaranteed; and moreover, the limit on equipment level is broken, the smelting can be finished simply in a converter single process, and the phosphorus removal efficiency exceeds 96%.

Description

technical field [0001] The invention relates to a method for smelting ultra-low phosphorus steel, belonging to the technical field of metal material smelting. Background technique [0002] Phosphorus is a harmful element in steel. It is easy to segregate at the grain boundary, causing the steel to be "cold and brittle", significantly reducing the low-temperature impact toughness of the steel, and causing low-temperature brittleness and temper brittleness of the steel. The requirements for phosphorus content in high-grade high-quality steel are becoming more and more stringent, especially for low-temperature steel, marine steel, and hydrogen-induced cracking-resistant steel, etc., requiring phosphorus content to be less than 0.010% or 0.005%. [0003] As the market demand for high-grade high-quality steel increases, low-phosphorus steel and ultra-low-phosphorus steel, as an indispensable part of the pure steel production process, have received more and more attention. Adoptin...

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Problems solved by technology

In the early 1980s, Japanese iron and steel companies represented by Nippon Steel and Sumitomo, as well as China's Taiyuan Iron and Steel Co., Ltd. and Baosteel successively developed and applied the technology of pretreatment and dephosphorization of molten iron in molten iron tanks and torpedo tanks. However, due to the large temperature drop of molten iron and the reaction interface Small, low steel scrap ratio (≤5%), difficult to treat dephosphorization slag (high alkalinity), poor treatment efficiency, etc., and limited by site conditions, domestic iron and steel enterprises have also studied and adopted the single slag method in the converter furnace, leaving The slag method, double slag method, and double slag remaining slag method are used to dephosphorize molten steel, but the single slag method is suitable for brand new materials. The iron process is easy to splash and cause safety hazards. The above methods also have the problem of dephosphorization instability; in the mid-to-late 1990s, Japan and domestic Baosteel developed the double-connected converter technology, and then Shougang, Chongqing Iron and Steel and Anshan Iron and Steel also adopted it. Duplex steelmaking process, but the duplex process requires the use of two converters, one as a dephosphorization converter and the other as a decarburization converter, and half-steel ladles are required to carry out the intermediate links, the temperature loss is large, and it is affected by the level of equipment and The difficulty of workshop transformation is limited, so it cannot be widely used

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