How does the austempering process for SAE 1070-1090 carbon steel wave springs minimize the risk of hydrogen embrittlement compared to traditional oil quenching?

Traditional oil quenching and tempering of high-carbon steel creates a martensitic microstructure which is highly susceptible to hydrogen embrittlement, especially during electroplating. Austempering involves an isothermal transformation to bainite. The resulting lower bainite structure offers a superior combination of ductility and toughness at high hardness levels (HRC 45-50). Because bainite is less sensitive to the interstitial hydrogen pressure that causes 'delayed fracture,' austempered wave springs exhibit a much lower failure rate in applications where hydrogen is introduced during acid cleaning or zinc plating processes. However, a post-plating bake (e.g., 190°C for 4-24 hours) remains mandatory.