Rolled steel bar for hot forging, hot-forged section material, and common rail and method for producing the same
US9994943B2 · kind B2 · utility
Assignees
Inventors
Key dates
| Filing date | Jul 11, 2017 |
| Grant date | Jun 12, 2018 |
| Priority date | — |
| Expiry date | Jul 11, 2037 |
Classification
- Technology area (CPC F)Mechanical Engineering; Lighting; Heating
- CPC primaryF02M2200/9053
- WIPO fieldMaterials, metallurgy
- WIPO sectorChemistry
Abstract
Rolled steel bar for hot forging consisting, by mass percent, of C: 0.25-0.50%, Si: 0.40-1.0%, Mn: 1.0-1.6%, S: 0.005-0.035%, Al: 0.005-0.050%, V: 0.10-0.30%, N: 0.005-0.030% with the balance being Fe and impurities, i.e., P: 0.035% or less and O: 0.0030% or less, wherein Fn1=C+Si/10+Mn/5+5Cr/22+1.65V−5S/7 is 0.90 to 1.20. The predicted maximum width of nonmetallic inclusions at the time when a cumulative distribution function obtained by extreme value statistical processing by taking the width of nonmetallic inclusion in an R1/2 part of a longitudinal cross section of the steel bar as W (mm) is 99.99% is 100 μm or narrower. The number density of sulfides each having a circle-equivalent diameter of 0.3 to 1.0 μm observed per unit area of the R1/2 part of a transverse cross section of the steel bar is 500 pieces/mm2 or higher.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.