| About this Abstract |
| Meeting |
MS&T21: Materials Science & Technology
|
| Symposium
|
New Frontiers in Physical Metallurgy of Steels
|
| Presentation Title |
Microstructure and Toughness Correlation in High Strength Q&T Boron Steels Microalloyed with Nb and Mo |
| Author(s) |
Irati Zurutuza, Nerea Isasti, Eric Detemple, Volker Schwinn, Hardy Mohrbacher, Pello Uranga |
| On-Site Speaker (Planned) |
Pello Uranga |
| Abstract Scope |
Suitable combination between alloy concept and processing is required for meeting the challenging market requirements for high strength steels produced by Direct Quenching (DQ) and tempering treatments. Even though the synergetic effect on tensile property improvement by combining boron and microalloying elements (Nb, Mo and Nb+Mo) is well-known, the impact of different microstructural aspects on Charpy impact toughness remains unclear. In the current presentation, the contribution of different microstructural aspects on toughness is evaluated, after DQ and tempering laboratory tests. Martensite unit size and dislocation density quantification was performed using EBSD. The detrimental effect of microstructural heterogeneity and carbides is also quantified. Additionally, an approach for impact transition temperature prediction is proposed for tempered martensite. Unit size refinement is shown to be the most effective mechanism for controlling simultaneously strength and toughness. The results suggest that Mo-B alloying concept shows the best yield strength-toughness balance. |