Hot-rolled steel sheet and manufacturing method thereof, and manufacturing method of cold-rolled steel sheet
US11066720B2 · kind B2 · utility
Assignee
Inventors
Key dates
| Filing date | Mar 22, 2016 |
| Grant date | Jul 20, 2021 |
| Priority date | — |
| Expiry date | Aug 19, 2037 |
Classification
- Technology area (CPC B)Performing Operations; Transporting
- CPC primaryB21B2001/225
- WIPO fieldMaterials, metallurgy
- WIPO sectorChemistry
Abstract
A Si/Mn ratio of steel material components of a base material is not less than 0.27 nor more than 0.90 in mass ratio, an internal oxide layer having a thickness of not less than 1 μm nor more than 30 μm is provided right below an oxide scale of a steel sheet surface layer portion, and regarding the internal oxide layer, an internal oxide in a crystal grain of the internal oxide layer is an oxide containing Si and having a thickness of not less than 10 nm nor more than 200 nm in a crystal grain in a range of greater than 0% and 30% or less of a thickness of the internal oxide layer from an interface between the internal oxide layer and base iron toward a direction of the surface layer oxide scale, one or more branches of the internal oxide exist in a cross section of 1 μm×1 μm square, and in any crystal grain boundary having a length of 1 μm, one or more of the internal oxides in the crystal grain are connected to an internal oxide of the crystal grain boundary to form a net-like structure.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.