Carbide Precipitation during Processing of Two Low-Alloyed Martensitic Tool Steels with 0.11 and 0.17 V/Mo Ratios Studied by Neutron Scattering, Electron Microscopy and Atom Probe

Two industrially processed low-alloyed martensitic tool steel alloys with compositions Fe-0.3C-1.1Si-0.81Mn-1.5Cr-1.4Ni-1.1Mo-0.13V and Fe-0.3C-1.1Si-0.81Mn-1.4Cr-0.7Ni-0.8Mo-0.14V (wt.%) were characterized using small-angle neutron scattering (SANS), scanning electron microscopy (SEM), Scanning transmission (STEM), atom probe tomography (APT). The combination of methods enables an understanding the complex precipitation sequences that occur in these materials during processing. Nb-rich primary carbides form at hot working, while Fe-rich auto-tempering precipitate upon quenching, cementite grow tempering when Mo-rich secondary also nucleate grow. number density increases time, after 24 h, it is two to three orders magnitude higher than carbides. A high important strengthen steels through hardening. results indicate carbide precipitates are initially MC character, whilst later they start appear as M2C. This change diffusion driven therefore mainly seen for longer times temperature 600 °C.