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Free machining steel with lead

A technology of free-cutting steel and inclusions, applied in the direction of furnace types, furnaces, heat treatment furnaces, etc., can solve the problems of insufficient machinability and achieve excellent machinability

Active Publication Date: 2015-11-04
NIPPON STEEL CORP
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0010] However, in the case of lead-containing free-cutting steel, sufficient machinability may not be obtained simply by simply controlling the form of MnS inclusions

Method used

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  • Free machining steel with lead
  • Free machining steel with lead
  • Free machining steel with lead

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Experimental program
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Embodiment

[0132] Lead-containing free-cutting steels were manufactured under various chemical compositions and manufacturing conditions, and the machinability was evaluated.

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Abstract

Provided is a free machining steel with lead having excellent machinability. A free machining steel with lead (1) according to an embodiment of the present invention contains, in mass%, 0.005 to 0.2% carbon (C), 0.3 to 2.0% manganese (Mn), 0.005 to 0.2% phosphorus (P), 0.01 to 0.7% sulfur (S), 0.03 to 0.5% lead (Pb), 0.004 to 0.02% nitrogen (N), and 0.003 to 0.03% oxygen (O), with the remainder comprising iron and impurities. Among free machining inclusions (8) in the steel, the ratio of the number of Pb-MnS inclusions having an equivalent circular diameter of at least 5 μm with respect to the total number of free machining inclusions (8) having an equivalent circular diameter of at least 5 μm is at least 5%. The free machining inclusions (8) are not more 200 μm long. The average of length of the free machining inclusions (8) in the steel having an equivalent circular diameter of at least 5 μm is not more than 50 μm. Among the free machining inclusions (8), there are at least 500 / mm2 having an equivalent circular diameter of at least 2 μm and having an aspect ratio of not more than 10.

Description

technical field [0001] The present invention relates to free-cutting steel, and more specifically, to lead-containing free-cutting steel containing lead. Background technique [0002] General mechanical products such as automobiles and electrical products consist of many parts. These components are mostly produced by machining. Therefore, "easy machinability", that is, excellent machinability is required for steel which is a raw material of components. [0003] Free-cutting steel has excellent machinability. Typical free-cutting steels include SUM23 and SUM24L specified in JIS standards, for example. Since Pb improves the machinability of steel, free-cutting steels often contain Pb. Hereinafter, free-cutting steel containing Pb is referred to as lead-containing free-cutting steel. [0004] In recent years, due to environmental considerations, free-cutting steels with suppressed Pb content and Pb-free free-cutting steels that do not contain Pb have been proposed. Howeve...

Claims

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Application Information

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IPC IPC(8): C22C38/00C22C38/60B21B3/02B22D27/04C21D8/00
CPCB22D11/001B21B3/02B22D11/22B22D27/04C21D7/13C21D8/00C21D9/22C22C38/00C22C38/002C22C38/008C22C38/02C22C38/08C22C38/12C22C38/16C22C38/18C22C38/60
Inventor 渡里宏二桥村雅之
Owner NIPPON STEEL CORP