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A metallurgical method for improving the as-cast sulfide morphology of medium-carbon and high-sulfur free-cutting steel

A technology of free-cutting steel and sulfide, applied in the field of iron and steel metallurgy, can solve the problems of unsatisfactory high-sulfur free-cutting steel, insufficient cutting performance, easy secondary oxidation, etc. The effect of improving the appearance and increasing the dissolved oxygen content

Active Publication Date: 2022-05-20
SGIS SONGSHAN CO LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

However, the Al content of this steel is high, the castability of continuous casting is not good, it is easy to secondary oxidation, block the nozzle, and affect the normal production; and the Al and N content is high, a large amount of AlN will be formed, which will easily lead to cracking on the surface of the continuous casting slab; in addition , the S content of the steel is low, the cutting performance is insufficient, and it cannot meet the requirements of high-sulfur free-cutting steel

Method used

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  • A metallurgical method for improving the as-cast sulfide morphology of medium-carbon and high-sulfur free-cutting steel
  • A metallurgical method for improving the as-cast sulfide morphology of medium-carbon and high-sulfur free-cutting steel
  • A metallurgical method for improving the as-cast sulfide morphology of medium-carbon and high-sulfur free-cutting steel

Examples

Experimental program
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Effect test

Embodiment 1

[0075] This embodiment provides a metallurgical method for improving the as-cast sulfide morphology of medium-carbon and high-sulfur free-cutting steel, specifically as follows:

[0076] (1) 130-ton top-bottom combined blowing converter smelting:

[0077] 1) The ladle is cleaned up, and the amount of residue is <150kg by visual inspection.

[0078] 2) Using 110 tons of molten iron + 20 tons of scrap steel as the main raw material, the C content in the molten steel is 0.11% when tapping, and the temperature is 1598°C; alloys such as carbon powder, ferrosilicon, and ferromanganese are added during the tapping process, Then add lime and low alkalinity synthetic slag for slag melting.

[0079] (2) LF refining, the refining time is controlled to 68 minutes:

[0080] 1) After arriving at the LF station, first add a small amount of lime and low-basicity synthetic slag to control the slag composition to meet the requirements of the present invention. When the LF refining finishes, t...

Embodiment 2

[0090] This embodiment provides a metallurgical method for improving the as-cast sulfide morphology of medium-carbon and high-sulfur free-cutting steel, specifically as follows:

[0091] (1) 130-ton top-bottom combined blowing converter smelting:

[0092] 1) The ladle is cleaned up, and the amount of residue is <150kg by visual inspection.

[0093] 2) Using 110 tons of molten iron + 20 tons of scrap steel as the main raw material, the C content in the molten steel is 0.10% when tapping, and the temperature is 1604°C; during the tapping process, alloys such as carbon powder, ferrosilicon, and ferromanganese are added for alloying. Then add lime and low alkalinity synthetic slag for slag melting.

[0094] (2) LF refining, the refining time is controlled to 65 minutes:

[0095] 1) After arriving at the LF station, first add a small amount of lime and low-alkalinity synthetic slag to control the slag composition to meet the requirements of the present invention. When the LF refi...

Embodiment 3

[0105] This embodiment provides a metallurgical method for improving the as-cast sulfide morphology of medium-carbon and high-sulfur free-cutting steel, specifically as follows:

[0106] (1) 130-ton top-bottom combined blowing converter smelting:

[0107] 1) The ladle is cleaned up, and the amount of residue is <150kg by visual inspection.

[0108] 2) Using 110 tons of molten iron + 20 tons of scrap steel as the main raw material, the C content in the molten steel is 0.16% when tapping, and the temperature is 1599°C; alloys such as carbon powder, ferrosilicon, and ferromanganese are added during the tapping process, Then add lime and low alkalinity synthetic slag for slag melting.

[0109] (2) LF refining, the refining time is controlled to 60 minutes:

[0110] 1) After arriving at the LF station, first add a small amount of lime and low-alkalinity synthetic slag to control the slag composition to meet the requirements of the present invention. When the LF refining finishes,...

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Abstract

The present application relates to the field of iron and steel metallurgy, in particular, to a metallurgical method for improving the morphology of as-cast sulfides of medium-carbon and high-sulfur free-cutting steel, including: converter or electric furnace smelting, LF refining, soft stirring, and continuous casting. During LF refining, the refining time is controlled to be 60-70 minutes, and it is divided into early, middle and late refining stages; among them, in the early stage of refining, a strict slagging system is implemented to ensure proper slag composition; in the middle stage of refining, alloying and oxygen content control are carried out; In the later stage of refining, carbon wire is added for carbon alloying. After continuous casting, the chemical composition of the cast billet made by mass percentage includes: C: 0.35-0.50%, Si: 0.10-0.35%, Mn: 1.30-1.65%, P: <0.025%, S: 0.08-0.35% , Al: 0.0003 ~ 0.0015%, O: 0.0015 ~ 0.0050%, Ca: 0.0005 ~ 0.0015%, the rest is Fe and other inevitable impurity elements. The sulfides of the cast slabs produced by this method are significantly improved in terms of morphology, size and spatial distribution uniformity, and the wire drawing cracking rate is significantly reduced.

Description

technical field [0001] The present application relates to the field of iron and steel metallurgy, in particular to a metallurgical method for improving the morphology of as-cast sulfides in medium-carbon and high-sulfur free-cutting steel. Background technique [0002] Medium-carbon high-sulfur free-cutting steel is mainly used for structural parts that require high cutting performance (high S content, generally S≥0.08%) and mechanical properties (medium carbon steel), such as car seat adjustment shafts, low-speed motors Shafts, gun barrels or other parts products; the relevant grades of this type of steel include SAE1144, SAE1141 (ASTM A1040-2010), 44SMn28, etc. in foreign countries, and Y40Mn, Y45Mn, Y45MnS, etc. in China. [0003] Medium-carbon and high-sulfur free-cutting steel wire rods are prone to cracking during cold drawing and shearing. The main reasons are poor surface quality of wire rods and poor plasticity of the matrix. In addition, a large number of studies ...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): C22C33/06C22C38/02C22C38/04C22C38/60C22C38/06B22D11/00C21C7/076C21C7/00
CPCC22C33/06C22C38/02C22C38/04C22C38/60C22C38/06C22C38/002B22D11/001C21C7/0025C21C7/076C21C7/0006Y02P10/20
Inventor 鲁金龙周楠刘栋刘志龙刘春林郭峻宇敖永明黄含哲王庆贺
Owner SGIS SONGSHAN CO LTD