Environment-friendly alloying method of metal bismuth for free-cutting steel

Abstract

The invention relates to an environment-friendly alloying method of metal bismuth for free-cutting steel, belongs to the technical field of metallurgy and aims to prevent violent reaction produced bydirection addition of metal bismuth, reduce smoke pollution, increase yield of bismuth and further normalize a bismuth alloying method. According to the method, metal bismuth is fed into molten steelin an alloy cored wire manner by a wire feeder, diameter of a bismuth cored wire is 8-14 mm, thickness of steel skin is 0.5-1.5 mm, and diameter of bismuth particles is 0-3 mm; bottom blowing stirringis performed on a steel ladle, feeding temperature is in a range of 1600-1780 DEG C, feeding rate is 80-110 m / min, and stirring is continued for 3-8 min after feeding. With adoption of the method, the problems of high volatilization, sedimentation and oxidation loss caused by low melting and boiling points and active nature of metal bismuth are solved, yield reaches 50% or higher, and splashing danger and a large amount of smoke pollution due to the violent reaction produced by direction addition of metal bismuth are effectively reduced.

Description

technical field [0001] The invention relates to an alloying method of free-cutting steel, in particular to an alloying method of metal bismuth of environment-friendly free-cutting steel. Background technique [0002] As the supply-side structural reform of the iron and steel industry continues to deepen, the state attaches great importance to the green development, transformation and upgrading of iron and steel enterprises. The development of green steel varieties is one of the important development directions of the steel industry. Non-toxic and harmless elements in steel varieties should not be added as much as possible. Customers and end users have higher and higher requirements for steel materials. At the same time, the environmental pollution inside steel plants The control is becoming more and more strict, so it is an inevitable requirement to avoid the addition of toxic elements. [0003] Lead is a common additive element in traditional free-cutting steel, which can ...

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Problems solved by technology

[0006] 1. The addition process will produce a violent reaction, causing molten steel to splash, which is easy to cause damage to production personnel and equipment

[0007] 2. Metal bismuth will oxidize rapidly at high temperature, accompanied by a large amount of smoke and dust, which will cause dust pollution to the environment

[0008] 3. Adding bismuth directly, because it contacts the surface of molten steel first, the oxidation loss is relatively large, it is difficult to reach the lower part of molten steel, and the yield is low, usually below 25%.

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