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.