Evaluation of Directed Energy Deposition 316LSi Stainless Steel Pressure Boundary Parts

There is great potential for additive manufacturing to be used for pressure boundary applications for power plant service. Both existing and new plants could benefit from the reduced lead times, design flexibility, and part consolidation possible with wire arc additive manufacturing. Various ASME code committees are working towards code rules for use of additive manufacturing. To further the industry’s understanding, this research program was undertaken on evaluating the properties of wire arc additive manufactured 316L stainless steel. This study performed microstructural characterization, chemical composition testing, mechanical testing, and nondestructive evaluation of multiple 1600 pound (700 kg) 316LSi stainless steel valve bodies produced using the gas metal arc directed energy deposition process followed by solution annealing. The results showed tensile behavior over a range of temperatures was comparable to wrought material. No variation in tensile behavior was observed with change in tensile sample orientation relative to the build direction. Room temperature charpy V notch absorbed energy was comparable to wrought material. Large grain sizes observed in the metallographic samples indicated adjusting the solution anneal temperature may be worthwhile. A comparison of radiography and ultrasonic testing results will be presented as well.