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Cryogenic impact fracture behavior of a high-Mn austenitic steel using electron backscatter diffraction and neutron Bragg-edge transmission imaging.
- Source :
-
Materials Science & Engineering: A . Nov2023, Vol. 887, pN.PAG-N.PAG. 1p. - Publication Year :
- 2023
-
Abstract
- A unique impact fracture behavior is found in a high-Mn austenitic steel (24Mn–4Cr-0.4C-0.3Cu) in this work. The steel exhibits concurrent twinning-induced plasticity (TWIP) effect and the transformation-induced plasticity (TRIP) effect. By analyzing the load-deflection curves recorded during Charpy impact testing, the resistance to crack initiation and propagation is quantified from the absorbed energy. The high-Mn steel demonstrates good resistance to crack initiation at 273 K and 77 K. However, as the temperature decreases from 273 K to 77 K, there is an accelerated transition from stable crack growth to unstable crack growth during impact, resulting in the deterioration of resistance to crack propagation. The plastic deformation of the impact-tested samples, especially in the region close to the crack-path profile was quantitatively analyzed using neutron Bragg-edge transmission (BET) imaging. The deformation zones, divided by using the width of the 200 Bragg edge, exhibit good agreement with the impact absorbed energy characteristics obtained from dynamic load-deflection curves. Moreover, the unstable growth transition point was roughly determined on the impact-tested sample. Then, the electron backscatter diffraction (EBSD) technique is employed to examine the deformation microstructure along the crack-path in the impact-tested samples. The results revealed the dual roles of TRIP effect in impact toughness of the high-Mn steel. On one hand, the TRIP effect plays a positive role in improving resistance to crack initiation and propagation. On the other hand, the excessive accumulation of brittle ε/α՛-martensite caused by the enhanced TRIP effect at 77 K leads to quasi-cleavage fracture, thereby playing a negative role. Finally, we discussed the prominent toughening mechanisms associated with the TWIP and TRIP effects, which greatly impact the impact fracture behavior. [ABSTRACT FROM AUTHOR]
Details
- Language :
- English
- ISSN :
- 09215093
- Volume :
- 887
- Database :
- Academic Search Index
- Journal :
- Materials Science & Engineering: A
- Publication Type :
- Academic Journal
- Accession number :
- 173233807
- Full Text :
- https://doi.org/10.1016/j.msea.2023.145768