Hypereutectoid steels with 0, 0.69, 1.29, and 1.95 wt pct aluminum were prepared. The samples were hot rolled at 1100 °C followed by cooling in air. The microstructure of the as-rolled samples was characterized using field emission-scanning electron microscopy (FE-SEM). The electron backscattered diffraction (EBSD) technique was used to identify the grain boundary phases. The steels have a pearlitic microstructure with different amounts of grain boundary cementite. A continuous grain boundary cementite network is present in the 0 wt pct Al steel. Grain boundary cementite formation is completely suppressed in the 1.29 wt pct Al steel. Phase diagram calculations show that aluminum increases the eutectoid temperature. However, the interlamellar spacing and pearlite colony size decrease with increase in aluminum content. Dilatometry measurements show that aluminum addition increases the undercooling below the eutectoid temperature. The yield strength increases with the decrease in interlamellar spacing and colony size. Very high ultimate tensile strengths (1200 to 1400 MPa) and improved elongations to failure (7 to 9 pct) are achieved in the as-rolled condition.
|Number of pages||7|
|Journal||Metallurgical and Materials Transactions A: Physical Metallurgy and Materials Science|
|Publication status||Published - 2010 Aug|
Bibliographical noteFunding Information:
The authors thank Drs. Kum Dong Wha and Eric Fleury for helpful discussions. This research was supported by POSCO (Grant No. 2008Z011) and the Korea Institute of Science and Technology (Grant No. 2E21080).
ASJC Scopus subject areas
- Condensed Matter Physics
- Mechanics of Materials
- Metals and Alloys