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Environmentally-friendly, Pb-free free-machining steel, and manufacturing method for same

A rapid cutting and steel ingot technology, applied in the direction of manufacturing tools, heat treatment equipment, furnace types, etc., can solve the problems of not providing MnS, etc., achieve excellent machinability, excellent hot rolling ability, and improve machinability

Inactive Publication Date: 2011-08-24
POHANG IRON & STEEL CO LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

But it relates to Bi-S based fast cutting steels, and it does not provide a method to control the shape of MnS as in the present invention

Method used

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  • Environmentally-friendly, Pb-free free-machining steel, and manufacturing method for same
  • Environmentally-friendly, Pb-free free-machining steel, and manufacturing method for same
  • Environmentally-friendly, Pb-free free-machining steel, and manufacturing method for same

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0108] In this embodiment, steel ingots having the compositions of Experimental Examples and Comparative Examples (SUM24L) in Table 1 below were prepared on the order of 200 kg in a high-frequency induction melting furnace. Here, the comparative example is the most widely used lead (Pb) free-cutting steel at present, that is, SUM24L. The steel ingots of the experimental example and the comparative example were prepared by the same experimental device and preparation method, and the size of the steel ingot prepared at this time was 230mm×230mm×350mm.

[0109] [Table 1]

[0110]

C

Si

mn

P

S

N(ppm)

other ingredients

Experimental example 1

0.09

0.01

1.0

0.08

0.25

98

Cr 0.4, Ti 0.2

Experimental example 2

0.08

0.02

1.1

0.08

0.30

78

Cr 0.1, Ti 0.02

Experimental example 3

0.08

0.03

1.2

0.08

0.30

83

Cr 0.3, Ti 0.006

Ex...

Embodiment 2

[0115] In the ingot rolling method, a free-cutting steel ingot with a size of 300mm×400mm after complete continuous casting is rolled into a billet with a size of 160mm×160mm, and subsequently, the billet is rolled into a diameter of 25mm in the wire rod rolling process of wire rod. At this time, the ingot and billet are heated and cooled by the usual free-cutting steel rolling conditions. Samples were collected from the wire rod after rolling, the total oxygen content was measured by a N / O analyzer, and the area and shape of MnS were observed by an optical microscope. Meanwhile, after completion of the wire rod rolling, the wire rod (Wire Rod) was cold drawn to prepare a cold drawn rod (CD Bar) with a diameter of 23 mm, after which the tool life was measured under the same conditions after cutting experiments using a CNC machine tool. The following table 2 shows the total oxygen content (ppm) of the wire rod obtained by the above experiment, with an area of ​​5 μm 2 per mm ...

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PUM

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Abstract

The present invention relates to a PB-free free-machining steel containing, by weight %, C: 0.03 - 0.13%, Si: 0.1% or lower, Mn: 0.7 - 2.0%, P: 0.05 - 0.15%, S: 0.2 - 0.5%, B: 0.001 - 0.01%, Cr: 0.1 - 0.5%, Ti: 0.05 - 0.4%, N: 0.005 - 0.015%, O: 0.03% or lower, the remainder being Fe and other inevitable impurities. The PB-free free-machining steel may contain MnS inclusions with a particle size of 5[mu]m2 or larger, existing in the numbers of 300 to 1000 per material mm2 at the cross-section of the rolling direction of a wire rod. Further, the present invention relates to a method for manufacturing environmentally-friendly, PB-free free-machining steel by properly controlling the total amount of oxygen in the process of manufacturing a steel material.

Description

[technical field] [0001] The present invention relates to an environmentally friendly lead-free free-cutting steel having excellent machinability and a preparation method thereof, and more particularly, to an environmentally friendly lead-free steel which has improved machinability and hot rolling characteristics and is produced in the following manner The fast cutting steel and its preparation method, namely: ① forming non-metallic inclusions and precipitation by adding appropriate amount of titanium (Ti), chromium (Cr) and nitrogen (N); ② controlling the manganese (Mn) / sulfur ( S) ratio of 3.5 or more; ③ limit the total oxygen (T.[O]) content to 300ppm or less; and ④ control the number of manganese sulfide (MnS) inclusions so that the area is 5μm 2 The amount of the above MnS is 300-1000 / mm on the section in the rolling direction 2 within range. [Background technique] [0002] A fast cutting steel refers to a steel whose machinability—often referred to as machinability—i...

Claims

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Application Information

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IPC IPC(8): C22C38/00C21D8/06C22C38/04C22C38/38
CPCC22C38/02C21D9/0075C22C38/28C21D2211/004C22C38/04C22C38/001C21D8/06C22C38/32
Inventor 安相馥李炯直李基澔李德洛
Owner POHANG IRON & STEEL CO LTD
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