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Bismuth adding technological method of bismuth-containing free-cutting steel

A free-cutting steel and process method technology, applied in the field of iron and steel metallurgy, can solve the problems of high concentration of alloying elements, rising production costs, serious element volatilization, etc., and achieve high yield, low production cost, and uniform distribution

Active Publication Date: 2019-08-06
SHANGHAI UNIV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

[0011] 1) Under the process conditions provided by the above-mentioned prior art, the volatilization of bismuth is relatively serious, and the yield is low, resulting in an increase in production costs;
[0012] 2) The above-mentioned prior art adopts one-time feeding of all cored wires, which will lead to excessive concentration of alloying elements in the molten steel, serious volatilization of elements and easy to cause segregation problems

Method used

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  • Bismuth adding technological method of bismuth-containing free-cutting steel

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Embodiment 1

[0057] In this embodiment, a bismuth addition process for bismuth-containing free-cutting steel, the production process of bismuth-containing carbon free-cutting steel is primary smelting→refining→wire feeding→continuous casting→rolling, measured at the end of LF furnace refining The composition of molten steel is C: 0.08%, Si: 0.03%, Mn: 1.15%, P: 0.09%, S: 0.30%, and the balance is iron and unavoidable residual elements. The composition of molten steel meets the requirements of this free-cutting steel According to this requirement, in the final stage of molten steel refining, after the adjustment of other components other than bismuth is completed, the feeding line addition process of bismuth-containing cored wire is carried out to prepare the target bismuth-containing free-cutting molten steel. The feeding line addition process method includes Follow the steps below:

[0058] a. Control the production conditions before feeding the line, mainly to control the molten steel sl...

Embodiment 2

[0076] This embodiment is basically the same as Embodiment 1, especially in that:

[0077] In this embodiment, a bismuth-added process for bismuth-containing free-cutting steel, the production process of bismuth-containing carbon free-cutting steel is primary smelting→refining→line feeding→continuous casting→rolling. The liquid composition is C: 0.14%, Si: 0.05%, Mn: 1.3%, P: 0.10%, S: 0.33%, and the balance is iron and unavoidable residual elements. The liquid steel composition meets the requirements of this free-cutting steel grade , at the end of molten steel refining, after the adjustment of other components except bismuth is completed, the feeding line addition process of bismuth-containing cored wire is carried out to prepare the target bismuth-containing free-cutting molten steel. The feeding line addition process includes the following steps :

[0078]a. Control the production conditions before feeding the line, mainly to control the molten steel slag layer, temperatu...

Embodiment 3

[0096] This embodiment is basically the same as the previous embodiment, and the special features are:

[0097] In this embodiment, a bismuth-added process for bismuth-containing free-cutting steel, the production process of bismuth-containing carbon free-cutting steel is primary smelting→refining→line feeding→continuous casting→rolling. The liquid composition is C: 0.14%, Si: 0.05%, Mn: 0.8%, P: 0.10%, S: 0.25%, and the balance is iron and unavoidable residual elements. The liquid steel composition meets the requirements of this free-cutting steel type , at the end of molten steel refining, after the adjustment of other components except bismuth is completed, the feeding line addition process of bismuth-containing cored wire is carried out to prepare the target bismuth-containing free-cutting molten steel. The feeding line addition process includes the following steps :

[0098] a. Control the production conditions before feeding the line, mainly to control the molten steel ...

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Abstract

The invention discloses a bismuth adding technological method of bismuth-containing free-cutting steel. In the last stage of refining, after other components except for bismuth are adjusted, adding ofa bismuth-containing cored wire is carried out. The method comprises the following specific steps of (1) control of production conditions before wire feed, wherein the slag layer, the temperature andthe oxygen activity of molten steel are controlled; (2) feed of the bismuth-containing cored wire; and (3) treatment after wire feed is finished. An intermittent wire feed method is adopted in the step (2), the bismuth-containing cored wire is intermittently fed by at least three times, the cored wire is 1 / n of the total quantity during feed of every time, n is the number of times, and the feed time interval ranges from 15 s to 20 s. The technological method has the following advantages that the wire feed process is stable, and severe splashing is avoided; the bismuth element yield is high and ranges from 15% to 40%, and the production cost is low; the forms of occluded foreign substances in the steel are good; and cutting performance is excellent. The bismuth adding technological methodis suitable for production of carbon free-cutting steel and free-cutting stainless steel and has quite large economic value in the field of the bismuth-containing free-cutting steel.

Description

technical field [0001] The invention relates to a preparation process of free-cutting steel, in particular to a preparation method of bismuth-based free-cutting steel, which is applied in the technical field of iron and steel metallurgy. Background technique [0002] Free-cutting steel refers to a type of steel that adds a certain amount of free-cutting elements to the steel to improve the cutting performance of the steel. With the increasing attention to environmental protection issues, the application of lead-based free-cutting steels has been limited, and relevant experts and scholars are looking for substitute elements for lead. [0003] Metal bismuth (Bi) is silver-white in appearance, has a strong metallic luster, is brittle, and has an orthorhombic crystal structure. Because metal bismuth is non-toxic, and has a low melting point and high flexibility similar to metal lead, it can improve steel machinability. Therefore, it is widely used as a substitute for lead in i...

Claims

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Application Information

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IPC IPC(8): C21C7/00C22C38/04C22C38/02C22C38/60C22C38/18C22C38/40
CPCC21C7/0006C21C7/0056C22C38/002C22C38/02C22C38/04C22C38/18C22C38/40C22C38/60
Inventor 付建勋赵梦豪胡绍晖张盼盼
Owner SHANGHAI UNIV
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