Process for production of steel bar or steel wire having an improved spheroidal structure of cementite
US4604145A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Jul 19, 1984 |
| Grant date | Aug 5, 1986 |
| Priority date | — |
| Expiry date | Jul 19, 2004 |
Classification
- Technology area (CPC C)Chemistry; Metallurgy
- CPC primaryC21D8/06
- WIPO fieldMaterials, metallurgy
- WIPO sectorChemistry
Abstract
Herein disclosed is a process for producing a steel bar or steel wire having an improved structure of spheroidal cementite. The process is characterized in that a finish rolling is conducted within a temperature range between Ar.sub.1 and Ar.sub.3 or Arcm with a reduction ratio of at least 20%. The cooling rate of the steel before the finish rolling should be controlled in the following manner: When the hardenability of the steel is not higher than that of 0.15% C plain carbon steel, it is preferable to cool the steel at a cooling rate higher than 250.degree. C./sec. When the hardenability of the steel is between those of 0.15% to 0.4% C plain carbon steel, it is preferable to cool the steel at a cooling rate higher than 10.degree. C./sec. When the hardenability of the steel is not lower than that of 0.4% C plain carbon steel, it is preferable to cool the steel at a cooling rate higher than 2.degree. C./sec. The annealing may be conducted on the same production line as the hot working of the steel for a shorter time duration by an isothermal treatment, slow cooling treatment or repeating treatment. The annealing may be conducted also by a usual annealing method.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.