| About this Abstract |
| Meeting |
MS&T21: Materials Science & Technology
|
| Symposium
|
Advances in Ferrous Metallurgy
|
| Presentation Title |
Hole Expansion Performance of Three High Strength Steels: Observation of Room Temperature Strain Ageing Phenomena |
| Author(s) |
Rachael Stewart, Mike J. Settle |
| On-Site Speaker (Planned) |
Mike J. Settle |
| Abstract Scope |
A delay between hole punching and expanding had a measured negative impact on the hole expansion performance (HER) of certain steels. A HSLA590GA, a Complex Phase780GI and a Dual Phase780GI steel were tested after delay times between 1
hour and 10 days. The HER of punched holes in all three steels decreased with delay time. Over the ten day study, the rate of decay followed a logarithmic trend in all three steels. The relative loss of performance after 10 days was similar across all three steels,
although the measured HER was different in each. The 24-hour loss in HER was avoided by storage in freezer, and machined holes did not lose performance with time. The time and temperature dependence of the phenomena suggest a diffusion mechanism. Hydrogen diffusion was ruled out by testing hydrogen charged samples. It is therefore theorized that a room temperature ageing phenomena at the sheared edge caused the observed decrease in HER. |