Title:
UNTEMPERED STEEL BAR
Document Type and Number:
WIPO Patent Application WO/2018/155604
Kind Code:
A1
Abstract:
Provided is an untempered steel bar that has excellent hot workability, has high yield strength, high fatigue strength, and excellent machinability after hot forging, and has excellent cracking characteristics even if bainite is generated after hot forging. This untempered steel bar has a chemical composition that: contains 0.39–0.55 mass% of C, 0.10–1.00 mass% of Si, 0.50–1.50 mass% of Mn, 0.010–0.100 mass% of P, 0.040–0.130 mass% of S, 0.05–0.50 mass% of Cr, 0.05–0.40 mass% of V, 0.10–0.25 mass% of Ti, 0.003–0.100 mass% of Al, and no more than 0.020 mass% of N, with the remainder being Fe and unavoidable impurities; and satisfies formula (1). The number density of Al2O3 inclusions that are at least 70.0 mass% Al2O3 and for which the square root of the area thereof is at least 3 μm is 0.05–1.00/mm2. Formula (1) 0.60≤C+0.2Mn+0.25Cr+0.75V+0.81Mo≤1.00.
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Inventors:
MIYAKOSHI YUSUKE (JP)
TAKASUGA MOTOKI (JP)
TAKASUGA MOTOKI (JP)
Application Number:
PCT/JP2018/006606
Publication Date:
August 30, 2018
Filing Date:
February 23, 2018
Export Citation:
Assignee:
NIPPON STEEL & SUMITOMO METAL CORP (JP)
International Classes:
C22C38/00; C22C38/60; C21C7/06; C21C7/064; C21C7/10; C21D8/06
Foreign References:
| JP2006336071A | 2006-12-14 | |||
| JP2004277841A | 2004-10-07 | |||
| JP2015025162A | 2015-02-05 |
Attorney, Agent or Firm:
ASCEND IP LAW FIRM (JP)
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