Hot deformation behavior of laser powder bed fusion newly developed MS400 grade maraging steel

Abstract

In this work, the hot deformation mechanism of as-printed laser powder bed fusion process (LPBF) newly developed MS400 grade maraging steel was investigated. The optimization processes allowed for obtaining samples with an average density of 8.200 ± 0.002 g cm−3 and hardness of 417 ± 5 HV. The hot compression procedure of maraging steel was carried out with the DIL 805 A/D dilatometer at different temperatures in the range of 1050 °C-1200 °C and strain rates of 0.01 s−1–1 s−1 in an inert gas atmosphere. The measured melt flow stress data were used to develop a constitutive model to determine the behavior of the alloy during hot deformation. The proposed equation can be used as an input to the finite element analysis to obtain the flow stress at a given strain, strain rate and temperature, useful for predicting flow localization or fracture during thermomechanical simulation. The activation energy for hot deformation was calculated to be 388.174 kJ mol−1, which corresponds to that of M350 grade. The proposed equation can be used during finite element analysis to calculate the flow stress at any strain, strain rate and temperature to determine the location of a flow or crack during a thermomechanical simulation.