The Influence of Silicon on the Precipitation Process in Maraging Stainless Steels

Using the Sandvik alloy 1RK91 as a reference material, a new test alloy with higher silicon content (Si+) was produced. Its hardness after 5 minutes at 475degC is more than 45% higher than that of the unaged alloy. The Si+ alloy shows no sign of softening during the ageing process up to 100 hours and by this time reaches the hardness of 650 Vickers. To understand these remarkable mechanical properties, the precipitation process of the new alloy has been investigated using energy-compensated tomographic atom probe analyses, local electrode atom probe analyses and energy-filtered transmission electron microscopy, and results were compared with those obtained from the investigations of alloy 1RK91