Method for manufacturing hot dip galvanized steel sheet
US9260774B2 · kind B2 · utility
Assignee
Inventors
Key dates
| Filing date | Mar 14, 2011 |
| Grant date | Feb 16, 2016 |
| Priority date | — |
| Expiry date | Oct 20, 2032 |
Classification
- Technology area (CPC B)Performing Operations; Transporting
- CPC primaryB21B2001/228
- WIPO fieldSurface technology, coating
- WIPO sectorChemistry
Abstract
An object of the present invention is to make it possible, without necessitating an alkali pretreatment, to form a zinc oxide layer having excellent sliding properties on a hot dip galvanized steel sheet not subjected to alloying after galvanizing and thus having a relatively low degree of surface activity. Another object of the present invention is to make it possible to manufacture a hot dip galvanized steel sheet having higher area ratio of Zn oxide layer formed on a coating surface and larger thickness of the Zn oxide layer. Specifically, the present invention provides a method for manufacturing a hot dip galvanized steel sheet comprising: subjecting a steel sheet to hot dip galvanizing and subsequent temper rolling; bringing the steel sheet into contact with acidic solution having pH buffering capacity; retaining the steel sheet for 1 second to 60 seconds after the contact with the acidic solution; and rinsing the steel sheet with water, to form a zinc oxide layer on a coating surface of the steel sheet, characterized in that the method further comprising:carrying out the temper rolling by either rolling the steel sheet first with a dull roll having Ra≧2.0 μm at rolling reduct…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.