[T6] AM Beam Based Technologies

[15B-T6-20] Argon-Filled Macro Pore Expansion — As Function of Material, Initial Pressure and Temperature

P. Mellin¹, *J. Gårdstam², S. Heino¹, J. Shipley², A. Magnusson², F. Forsberg³, B. Forssgren⁴, P. Waernqvist⁴ (1.Swerim AB, Sweden, 2.Quintus Technologies AB, Sweden, 3.Luleå University of Technology, Sweden, 4.Ringhals AB, Sweden)

Keywords:HIP, porosity, argon

We present here a study on capsules that contain a huge 2 cm³ cylindrical cavity. This cavity is sealed under 100% argon, at 50 °C and 1 atm. Using HIP (equipped with URQ) this cavity shrinks to an approximate size of 0.01 cm³. Upon stepwise reheating the pressure increases; for IN718 the cavity expands above 900 °C (here pressure is 832 bar), while for 316L the cavity expands above 1000 °C (here pressure is 875 bar). Conditions at which expansion occurs are not far away from HIP conditions, which makes sense. Also, the pressure inside a pore seems like a good indicator for if expansion will occur. We compare these results to studies of pore expansion in L-PBF material (both 316L and IN718) and conclude that the pore pressure in L-PBF material must be lower than atmospheric, since expansion occur at higher temperatures than for our capsules.