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Bismuth Addition Technology for Free Cutting Steel Containing Bismuth

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 alloy elements, serious volatilization of elements, and rising production costs, and achieve high yield, low production cost, and stable feeding process.

Active Publication Date: 2021-04-09
SHANGHAI UNIV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

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 Addition Technology for Free Cutting Steel Containing Bismuth
  • Bismuth Addition Technology for Free Cutting Steel Containing Bismuth
  • Bismuth Addition Technology for Free Cutting Steel Containing Bismuth

Examples

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Effect test

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 process method for bismuth-containing free-cutting steel. In the final stage of refining, after the adjustment of other components except bismuth is completed, the bismuth-containing cored wire is added. The specific steps are as follows: 1) Production before wire feeding Condition control, controlling the slag layer, temperature and oxygen activity of molten steel; 2) feeding of bismuth-containing cored wire; 3) processing after wire feeding, wherein, the step 2) adopts intermittent wire feeding method , Feed the bismuth-containing cored wire intermittently at least 3 times, each feeding of the cored wire accounts for 1 / n of the total amount added, n is the number of times, and the interval between each feeding is 15-20s. The technological method of the invention has the following advantages: the wire feeding process is stable without violent splashing; the yield of bismuth element is high, reaching 15-40%, and the production cost is low; the shape of inclusions in steel is good; and the cutting performance is excellent. It is suitable for the production of carbon free-cutting steel and free-cutting stainless steel, and has great economic value in the field of 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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Patent Type & Authority Patents(China)
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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