Aluminum-containing cold forging steel smelting process

Abstract

The invention discloses an aluminum-containing cold forging steel smelting process, comprising the steps of blast furnace molten iron making, processing by a converter, refining and continuous casting, wherein requirements of molten iron are as follows: P is not more than 0.10%, Si is not more than 0.50% and not less than 0.30%, S is not more than 0.030%; requirements in converter refining are as follows: CaO is not less than 85%, activity degree is not less than 280 and SiO2 in fluorite is not more than 6%; low-Si pre-melted slag or refining agent replaces partial CaO and fluorite in a converter steel discharging process for rapid slag making, a refining furnace deoxidizing agent is applicable to slag deoxidization after stirring calcium carbide and aluminum particles, and Si-containing material is prohibited; during continuous casting, pure Ca lines are applicable between a medium packet impact zone and various flows, so that calcium aluminate which is low in melting point and is from reaction of Al2O3 generated from medium packet through secondary oxidation and Ca floats and is removed. The process can reduce the content of Si in steel, improve Al content and guarantee continuous pouring of molten steel.

Description

technical field [0001] The invention belongs to the field of metallurgy and relates to a steel smelting process, in particular to an aluminum-containing cold heading steel smelting process. Background technique [0002] Cold heading steel wire rods are generally low and medium carbon high-quality carbon structural steel and high-quality alloy structural steel, which are used for cold heading to manufacture various mechanical standard parts and fasteners, such as bolts, nuts, screws, rivets, self-tapping screws Wait. Because the cold heading process requires the steel to have a high degree of cleanliness, the content of Si and Al in the steel is controlled, and the controlled rolling and controlled cooling process is adopted to avoid the appearance of martensite, bainite and Widmansite, so that the steel has Fine grain and carbide spheroidization structure to improve the plasticity and cold upsetting performance of steel. National standards have high requirements for it...

AI Technical Summary

Problems solved by technology

At present, the main difficulty is to control the Si content in the steel at a low level to ensure the cold heading performance of the steel. At the same time, in order to ensure the purity of the molten steel, Al deoxidation is used in the smelting process and the Al in the steel is controlled at a high level. Pouring poses a big problem. High Al can easily cause nodules in the continuous casting nozzle, resulting in fluctuations in the liquid level of the mold and molten steel slag, thereby reducing the purity of the steel and even exceeding the standard.

[0004] At present, most steel mills use blast furnace hot metal-converter-refining-continuous casting production process to produce cold heading steel, but the Si content in the steel cannot be stably controlled at a low level

At the same time, due to the use of Al for deoxidation, nodules are prone to occur in continuous casting, and continuous casting in multiple furnaces cannot be realized, and the purity of molten steel is also low, which indirectly increases production costs.

Images