The Effect of Bi on the Selective Oxide Formation on CMnSi TRIP Steel
Abstract
The effect of Bi addition on the selective oxidation and the galvanizability of CMnSi transformation-induced plasticity (TRIP) steels was studied by hot dip galvanizing laboratory simulations. Bi-added TRIP steels were intercritically annealed at 1093 K (820 °C) and galvanized in a 0.22 wt pct Al-containing Zn bath. The oxide morphology was investigated by scanning electron microscopy, transmission electron microscopy, and 3D atom probe tomography. Bi formed a Bi-enriched surface layer during the intercritical annealing. A decrease of the oxygen permeability was observed with increasing Bi addition. The internal oxidation was suppressed in Bi-added CMnSi TRIP steel. The surface oxide morphology was changed from a continuous layer morphology to a more lens-shaped morphology. The galvanizability of the Bi-added TRIP steel was improved by the combination of the change of the oxide morphology and the dissolution of the Bi-enriched surface layer during immersion of the strip in the Zn bath.
- Publication:
-
Metallurgical and Materials Transactions A
- Pub Date:
- November 2016
- DOI:
- 10.1007/s11661-016-3735-9
- Bibcode:
- 2016MMTA...47.5474O
- Keywords:
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- Trip Steel;
- Intercritical Annealing;
- Steel Matrix;
- Glow Discharge Optical Emission Spectroscopy;
- Inhibition Layer