Precipitation of multiple carbides in martensitic CrMoV steels - experimental analysis and exploration of alloying strategy through thermodynamic calculations

Martensitic microstructures with engineered precipitation of nano-scale carbides formed during tempering are key in the development of, for example, wear-resistant steels. These steels often experience multiple carbide precipitation with evolving compositions and where the metastable phases transition to more stable carbide phases. In the case of low alloy CrMoV steels, the incomplete understanding of the complex precipitation evolution during tempering is preventing their further optimization. Therefore, in the present work we perform an in-depth experimental investigation of the precipitation of carbides in an Fe–0.32 C–1.4 Cr–0.8 Mo–0.14 V–1.1 Si–0.8 Mn–0.7 Ni (wt.%) martensitic steel tempered at 550 °C by transmission electron microscopy and atom probe tomography. The experimental data is compared to thermodynamic calculations and these are subsequently used to expose further potential improvements to the alloying strategy.