Title:
ELECTRIC RESISTANCE WELDED STEEL PIPE FOR HIGH-STRENGTH THIN HOLLOW STABILIZER AND MANUFACTURING METHOD THEREFOR
Document Type and Number:
WIPO Patent Application WO/2018/079398
Kind Code:
A1
Abstract:
Provided is a method for manufacturing an electric resistance welded steel pipe for a high-strength thin hollow stabilizer. A hot rolled sheet is prepared by heating a steel material having a composition containing, on a mass basis, 0.20-0.40% of C, 0.1-1.0% of Si, 0.1-2.0% of Mn, 0.01-0.10% of Al, 0.01-1.0% of Cr, 0.01-0.05% of Ti, 0.0005-0.0050% of B, 0.0001-0.0050% of Ca, and 0.010% or less of N to a temperature of 1000-1300ºC, terminating hot rolling at 750-950ºC, cooling, winding the steel material into a coil shape at 500-650ºC, and then skin pass rolling at a rolling reduction of 0.3% or more. The hot rolled sheet is electric resistance welded into an electric resistance welded steel pipe, reheated to a temperature of 800-110ºC and then subjected to hot reducing at a hot rolling termination temperature of 850ºC or lower at a cumulative diameter reduction ratio of 75% or less. This results in a thin electric resistance welded steel pipe wherein a decarburized layer on the inner surface side of the pipe extends 120 µm or less in the thickness direction from the surface, the inner surface of the pipe has a surface roughness Ra of 0.01-5.0 µm, and the YR is 65% or more. The thin pipe product has a hardness of 450 HV or more when measured as Vickers hardness after quenching/tempering and has excellent fatigue resistance characteristics.
Inventors:
ARATANI MASATOSHI (JP)
KOKUBO SHINSAKU (JP)
HORI HIROMICHI (JP)
KAWABATA YOSHIKAZU (JP)
MATSUI RYOJI (JP)
KOKUBO SHINSAKU (JP)
HORI HIROMICHI (JP)
KAWABATA YOSHIKAZU (JP)
MATSUI RYOJI (JP)
Application Number:
PCT/JP2017/037824
Publication Date:
May 03, 2018
Filing Date:
October 19, 2017
Export Citation:
Assignee:
JFE STEEL CORP (JP)
International Classes:
C21D8/10; B21C37/08; C21D8/02; C21D9/08; C21D9/46; C22C38/00; C22C38/38; C22C38/58
Domestic Patent References:
| WO2013175821A1 | 2013-11-28 | |||
| WO2017056384A1 | 2017-04-06 |
Foreign References:
| JP2006312773A | 2006-11-16 | |||
| JP2007217736A | 2007-08-30 | |||
| JP2003201543A | 2003-07-18 | |||
| JP2007270349A | 2007-10-18 | |||
| JP2009249650A | 2009-10-29 | |||
| JP2005076047A | 2005-03-24 | |||
| JP2006206999A | 2006-08-10 | |||
| JP2008208417A | 2008-09-11 | |||
| JP2010189758A | 2010-09-02 |
Other References:
See also references of EP 3476953A4
Attorney, Agent or Firm:
KUMASAKA Akira et al. (JP)
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