Pressure effect on the structural, magnetic and thermophysical properties of X12Cr13 martensitic stainless steel prepared by powder metallurgy method

Low carbon (C: 0.03-0.15%) and high Cr contents (Cr: 11-15%) martensitic stainless steel (MSS) is widely used for industrial applications due to its good mechanical properties and corrosion resistance. In this study, we investigated the pressure effect on the structural, magnetic and thermophysical properties of X12Cr13 MSS which was compacted using powder metallurgy method under 400 and 600 MPa pressures and sintered at 1200 degrees C temperature for an hour under Ar atmosphere. Pressing and sintering processes resulted in increased density of microstructures from 5.84 g/cm3 to 6.12 g/cm3, decreased porosity from 7.58% to 3.39%, increased hardness from 93.24 HB to 110.09 HB (N/ mm2) and decreased carbide particles from 2.65% to 2.13 wt% in the structures. We observed alpha-Fe, gamma-Fe and M23C6 (M: Cr or Fe) phase formations in the structure due to the applied pressure and the sintering process. The magnetic properties of these steels have been investigated as a function of temperature between 300 and 400 K and applied magnetic field of +/- 4 T. We observed improved magnetic properties with increasing pressure, and ferromagnetic to paramagnetic phase transition occurred from 300 K to 400 K. While maximum saturation magnetization is found to be 70 emu/g at 300 K for 600 MPa sample, maximum magnetic susceptibility and permeability for 600 MPa sintered sample are recorded as 17.13 and 1.08 m3/kg, respectively. Also, the maximum specific heat capacity and enthalpy are recorded as 1.85 J/g degrees C and 536.05 J/g (at 579 degrees C temperature) on the sample compacted on the 600 MPa pressure, respectively.