Incremental step load testing was used in accordance with ASTM F1940 to rank a number coating processes used in the fastener industry for their propensity to cause internal hydrogen embrittlement. The results showed that coating permeability has a first order effect, while the quantity of hydrogen introduced by the process has a second order effect. Pure zinc electroplating processes, alkaline and acid, were found to be the most embrittling, owing to the low permeability of zinc. The least embrittling processes were zinc-nickel, alkaline and acid, owing to the high permeability of Zn-Ni coatings. Non-electrolytic processes, namely phosphating, mechanical galvanising, DacrometRTM and Magni 555RTM were found to be non-embrittling. Hot dip galvanising was found to be highly embrittling, evidently due to trapped hydrogen being released by the thermal shock of up-quenching upon immersion in molten zinc. The full effect of up-quenching on the metallurgical and mechanical properties of high strength steel requires further investigation.
| Identifer | oai:union.ndltd.org:LACETR/oai:collectionscanada.gc.ca:QMM.112560 |
| Date | January 2007 |
| Creators | Brahimi, Salim. |
| Publisher | McGill University |
| Source Sets | Library and Archives Canada ETDs Repository / Centre d'archives des thèses électroniques de Bibliothèque et Archives Canada |
| Language | English |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
| Format | application/pdf |
| Coverage | Master of Engineering (Department of Mining and Materials Engineering.) |
| Rights | All items in eScholarship@McGill are protected by copyright with all rights reserved unless otherwise indicated. |
| Relation | alephsysno: 002762998, proquestno: AAIMR51450, Theses scanned by UMI/ProQuest. |
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