Abstract
The toughness and the resistance to delayed fracture are deteriorated with increasing strength of martenstic steels. It has been reported that these properties could be improved by grain refinement of martensite. In this study, the influence of both hot stamping conditions such as heating rate, heating temperature, cooling rate, and material conditions such as hot band microstructure, cold rolling reduction, addition of micro-alloys on the grain refinement of hot stamped ultra-high strength martenstic steel components are investigated. The investigation revealed that low temperature and short time heating, high heating and cooling rates, the decrease in the coiling temperature of hot bands, the increase in cold rolling reduction and addition of micro-alloys are preferable for grain refinement of martensite. The mechanism of the grain refinement was discussed from the viewpoints of the increase in the nucleation rate of austenite during the α→γ transformation and the suppression of the austenite grain growth.
| Original language | English |
|---|---|
| Pages (from-to) | 475-483 |
| Number of pages | 9 |
| Journal | Tetsu-To-Hagane/Journal of the Iron and Steel Institute of Japan |
| Volume | 99 |
| Issue number | 7 |
| DOIs | |
| Publication status | Published - Jul 30 2013 |
Keywords
- Grain refinement of martensite
- Hot stamping
- Rapid heating
- Reverse transformation
- Ultrahigh strength steel
ASJC Scopus subject areas
- Condensed Matter Physics
- Physical and Theoretical Chemistry
- Metals and Alloys
- Materials Chemistry