Impact toughness of a 12% Cr martensitic steel: Conventional heat treatment vs. thermo-mechanical processing

Abstract

The impact toughness together with determination of the ductile–brittle transition temperature for the 12 %Cr steel with the low N and high B contents subjected to conventional heat treatment and thermo-mechanical processing have been investigated. The thermo-mechanical processing includes the interim hot forging and long-term annealing at 1050 °C with the aim to dissolve the delta-ferrite and coarse W-rich particles, as well as to decrease the particle number density of M23C6 carbides along the lath boundaries and to precipitate V-rich MX phase. The temperature dependence of Charpy energy curves including upper and lower shelf energy is found to be shifted in a side of higher energies. The ductile–brittle transition temperature decreases from 70 °C to (45–50)°C.