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Ozone depletion: a view from the grass roots.

Research output: Contribution to Journal/MagazineJournal article

Published
<mark>Journal publication date</mark>07/1996
<mark>Journal</mark>Atmospheric Environment
Issue number14
Volume30
Pages (from-to)i-ii
Publication StatusPublished
<mark>Original language</mark>English

Abstract

Early failures occurred with two sizes of wheel bolts used for attaching front wheels and dual rear wheels to heavy truck hubs. Failure resulted in fracture of the bolts, and was a response to the material and process specification which produced a steel microstructure highly susceptible to hydrogen-assisted stress cracking. The microstructure resulted from an alloy steel that was carburized, heat treated, and then zinc plated. This combination of material and processing produced a high-strength SAE Grade 8 bolt (equivalent to an ISO 10.9 grade) with a hard, brittle case and an anodic zinc coating. A slight misalignment of the wheel bolt coupled with a ball seat mounting design for the wheel nuts created a combined axial and bending stress that exceeded the threshold for hydrogen-assisted stress cracking.