Process for melting 25Cr2Ni4MoV rotor steel

Abstract

The invention discloses a process for melting a 25Cr2Ni4MoV rotor steel. The process particularly comprises the following steps: (1) selecting the raw materials; (2) performing primary smelting in an electric-arc furnace; (3) refining by an LF furnace; (4) performing carbon deoxidization; (5) pouring. When preparing the materials, the high-quality steel scrap and the stub bar are selected, the harmful residual element contents As, Sn, Sb, Cu, Al in the steel solution are strictly controlled to met the process requirement; the operation of dominant slag and steel is processed during electric furnace tapping so that the rephosphorization is effectively prevented; the deoxidization method is a vacuum carbon deoxidization process, so that the molten steel non-metallic inclusion and the gas content are effectively reduced and the purity of the molten steel is greatly increased.

Description

technical field [0001] The invention belongs to the technical field of steelmaking process, and in particular relates to a smelting process of 25Cr2Ni4MoV rotor steel. Background technique [0002] With the rapid development of the power industry in recent years, thermal power equipment has entered a higher-level development period, mainly focusing on improving efficiency and reducing pollution, energy consumption and cost. Power equipment is developing in the direction of high parameters, large capacity and automation. With the continuous enlargement of the unit and the increase in the size and weight of the rotor forgings, the requirements for the mechanical properties, metallurgical quality, forging equipment and quality of the materials are also getting higher and higher. This also correspondingly puts forward higher requirements for the steel ingot smelting process. [0003] 25Cr2Ni4MoV steel is a low-carbon high-strength alloy structural steel with superior mechanica...

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Problems solved by technology

The deoxidation of the traditional smelting process is generally through the precipitation deoxidation method of adding deoxidizer at the end of the primary smelting furnace and LF refining. The deoxidation products are mostly high melting point inclusions such as alumina and silicon oxide. Float in time to remove and stay in the molten steel, resulting in nodules in the nozzle during the pouring process of molten steel, resulting in a high content of inclusions in the steel ingot, which seriously affects product quality; in addition, the V content is also a key factor affecting the quality of the rotor. Cracking during the process, too low will not only make it difficult to guarantee product performance, but also cause coarse grains in the heat treatment of the rotor; at the same time, studies have shown that phosphorus in the steel will cause temper embrittlement of the steel, and sulfur will reduce the toughness of the steel; When the hydrogen content is high, the phase transformation during the cooling process will cause serious internal stress, and white spots will appear in the hydrogen-rich part of the forging, resulting in a serious longitudinal cracking tendency; impurity elements such as As, Sn, Sb in the steel will also temper embrittlement of steel

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