Qualification of the laser powder bed fusion (L-PBF) manufacturing process for water-cooled protective components made from 316 L for plasma-exposed use in the Stellarator fusion device Wendelstein 7-X

A multi-stage qualification program of components, made by the additive manufacturing process (AM process) of laser powder bed fusion of metals (L-PBF) was performed. The aim of the qualification program was the test of the currently available L-PBF manufacturing options for practical usability at Wendelstein 7-X (W7-X) and the fabrication of water-cooled protective components made from 316 L stainless steel for W7-X diagnostics. The qualification program included a whole series of examinations and tests to provide information on the following characteristics: mechanical material properties, helium tightness, burst pressure, weldability, corrosion behavior, durability during thermal cycles, microwave durability, machinability, surface roughness, hydraulic pressure loss of cooling channels, outgassing behavior in vacuum, magnetic permeability, cobalt content, internal defects and geometric accuracy. The qualification program also resulted in recommendations for heat treatment parameters and a proposal for an indicator of process faults. After successful qualification, 13 L-PBF-components of four different component types with internal cooling channels were manufactured and installed in the plasma vessel of W7-X.