Tag Archives: Hydrogen Embrittlement

Protecting Fasteners from Corroding Part 1: Basics of Corrosion and Protection Mechanisms

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Reprint from China Fastener World Magazine, Vol. 190

The man walked to his tool box, selected the right sized socket and returned to the piece of machinery he was trying to repair. He stared for a moment at the nut he was trying to loosen. It was badly corroded but he had done this many times before. Carefully seating the socket fully on the nut he began to apply pressure. At first nothing happened but then he felt a tiny change in the resistance, reinvigorating his incentive to keep pushing on the bar. Just as he thought he had given it his all, a resounding loud snap occurred catapulting him and his tools forward as his efforts were no longer restrained by the once stubborn but now broken bolt and nut. Crashing into the floor, he yelped in pain and cussed his misfortune.

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Hydrogen Embrittlement

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Reprint from China Fastener World Magazine, Vol. 51

If you are in the fastener industry long enough you will eventually experience first-hand or hear stories about a hydrogen embrittlement failure. In fact, the fear of this potential failure is so palpable that many of the stories have taken on urban legend status. Although many of these stories may not be as exceptional as they are made out to be, there is no denying the fact that a hydrogen embrittlement failure can be painful to all the parties involved.

One might ask why a hydrogen embrittlement failure is any worse than other fastener failure. This is a good question. Perhaps one would argue that it is no worse than any other, we all understand that a failure is a failure. However, others might argue that it is worse because it comes with no warning and its fallout is completely unpredictable. In one case, it might affect almost an entire lot of parts but in another only a small percentage. Additionally, although parts can have all the ingredients for a problem, it only strikes after the parts are put into service. This makes such failures especially difficult because containment and restoration is often extremely costly.

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Basics of Austempering — A Thermal Hardening Process for Fasteners over HRC40

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From Fasteners Technology International, February 2014

What do many lawn mower blades and automotive spring steel clips have in common? When considering their applications, probably very little, but in their product realization, they likely have both employed Austempering (a heat treating process) as their method for strengthening and toughening. Although over 75 years old, Austempering is a heat treating process that has really only become practically viable and commercially employed in the last 40 years. Austempering will likely never supplant conventional quench and tempering processes for the majority of threaded fastener applications, yet some of the advantages are so compelling that there will always be interest and activity in expanding the current application field. At hardness levels above 40 HRC, Austempered parts demonstrate improved mechanical properties such as toughness, ductility and strength over their quench and tempered counterparts of comparable hardness. Austempered parts undergo significantly less distortion, which reduces the subsequent cost of post heat treatment remediation.

Since this technology has direct application for the fastener industry, both now and well into the future, it is advisable for practitioners of the industry to have an understanding of the basics and enough information to consider what future possibilities might be waiting out there. The goal of this article is to provide a simplified explanation of this complex process and to explain some of its more compelling advantages.

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