Issue |
Metall. Res. Technol.
Volume 113, Number 4, 2016
|
|
---|---|---|
Article Number | 409 | |
Number of page(s) | 14 | |
DOI | https://doi.org/10.1051/metal/2016019 | |
Published online | 06 June 2016 |
Intermetallic spike growth mechanisms in 316L stainless steel in contact with molten 55%Al-Zn metal coating alloy
BlueScope Product Innovation and Technology,
Port Kembla,
NSW
2505,
Australia
e-mail: nega.setargew@bluescopesteel.com
Received:
22
December
2015
Accepted:
11
March
2016
Immersed pot hardware used in 55%Al-Zn metal coating pots is fabricated from austenitic stainless steel grade 316L. This alloy is selected for immersed pot hardware applications because of its good corrosion performance in contact with the metal coating bath. The steel however, can be susceptible to excessive corrosion damage after prolonged service at elevated temperatures. The types of corrosion damage observed in immersed pot hardware include intergranular and pitting corrosion and the formation of cone shaped intermetallic alloy spikes, often referred to as horn growth defects. When 316L reacts with molten 55%Al-Zn coating bath, two distinct interfacial alloy layers are formed. The alloy layers provide a diffusion barrier and minimise excessive dissolution of the steel and prevent the formation and growth of the alloy spikes. Laboratory immersion experiments show that when the two interfacial diffusion barrier alloy layers are absent, alloy spike is promoted. It is also found that the diffusion of aluminium into the substrate steel leads to γ to α-ferrite transformation in the steel resulting in a self-sustaining growth process for continued intermetallic alloy spike growth. The microstructures of the laboratory produced alloy spikes are compared with those observed in sink rolls and other immersed pot equipment. Alloy spike growth mechanisms are discussed together with experimental verification of the proposed alloy spike growth mechanisms.
Key words: 316L pot hardware / alloy spike / modifiedτ5cparticles / AlFeSi IMC particles / Fe-Zn alloy / Fe-Al IMCs
© EDP Sciences, 2016
Current usage metrics show cumulative count of Article Views (full-text article views including HTML views, PDF and ePub downloads, according to the available data) and Abstracts Views on Vision4Press platform.
Data correspond to usage on the plateform after 2015. The current usage metrics is available 48-96 hours after online publication and is updated daily on week days.
Initial download of the metrics may take a while.