Comparison of early stages of precipitation in Mo-rich and Mo-poor maraging stainless steels

Journal article, 2007

The precipitation process during ageing in the Mo-poor alloy Carpenter 455 has been investigated by three-dimensional atom probe (3DAP) and energy-filtered transmission electron microscopy. The ageing treatment was performed at 475 degrees C for 5 min, 25 min, 1 h and 2 h. The precipitation of a mixed Ni-, Ti- and Cu-rich phase was observed after 25 min of ageing. A complete separation between Ni/Ti-rich and Cu-rich regions occurred within 1-2 h of ageing. After 2 h of ageing at 475 degrees C, coarsening of the eta-Ni3Ti precipitates was observed. Moreover, large Ni/Ti-rich and Cu-rich particles were observed in the lath boundaries after 2 h of ageing. The results were compared with the precipitation process in the Mo-rich alloy 1RK91. Copyright (C) 2007 John Wiley & Sons, Ltd.