| About this Abstract |
| Meeting |
Materials Science & Technology 2011
|
| Symposium
|
Processing, Microstructure and Properties of Cast Irons and Cast and Forged Specialty Steels
|
| Presentation Title |
The Effects of Cobalt on the Ductile-to-Brittle Transition Temperature of Precipitation Strengthened Ultra-High Strength Steels |
| Author(s) |
Warren Garrison |
| On-Site Speaker (Planned) |
Warren Garrison |
| Abstract Scope |
While Stoloff et. al reported in 1965 cobalt significantly increased the ductile-to-brittle transition temperature (DBTT) of iron, there are no studies of the effects of cobalt on the DBTT of ultra-high strength steels. Consideration of the toughness of several ultra-high strength precipitation strengthened steels suggests cobalt raises the DBTT of these steels and this increase is reduced by nickel additions and by austenite in the microstructure. Available evidence shows precipitation strengthened steels, including secondary hardening steels, which contain large amounts of cobalt and low amounts of nickel have very low toughness at room temperature. Only when cobalt additions are balanced by nickel additions, as is the case for the maraging steels and steels of the AerMet 100 type, can high toughness be achieved at room temperature. The toughness of experimental precipitation strengthened stainless steels suggest austenite in the structure helps reduce the increase in the DBTT caused by cobalt additions. |
| Proceedings Inclusion? |
Definite: A CD-only volume |