Effect of Si and Al on Retained Austenite Stabilization during Q&P and Galvannealing Process

The present contribution concentrates on the different effects of Si and Al on the carbide precipitation and austenite decomposition during the Q&P-process and an additional galvannealing treatment of up to 560°C. These effects have been investigated by dilatometry (derivation of relative length change) and differential scanning calorimetry (heat flow) during tempering. It was possible to show the beneficial effect of Si on retarding the carbide precipitation in tempered martensite and thereby the ability to stabilize higher amounts of retained austenite compared to Al. Furthermore, the effect on retained austenite decomposition during Q&P and subsequent galvannealing could be demonstrated. Here, Al has the benefit to increase the thermal stability of austenite during galvannealing.