Defect characteristics within SLM-fabricated GH3536 superalloy dependence on μCT characterization

Abstract

GH3536 superalloy samples were made by selective laser melting (SLM) with a parameter combination of laser power and scanning speed. The porosity and defect characteristics within the samples were characterized by μCT technique, and the defect types as well as the morphologies of molten pool were analyzed using optical microscope and scanning electron microscope. The results show that process parameters are closely related with defect characteristics and the morphologies of molten pool. As the laser power and scanning speed are optimized, continuous molten pool with a higher aspect ratio overlaps well with each other. The porosity in the fabricated samples is far less than 0.01%, and with randomly distributed small pores. When the deviation from the optimized process parameters occurs, not only larger voids are formed at the interface of discontinuous molten pool, but also the process instability are increased, resulting in the formation of minor amounts of lamellar lack of fusion. The latter two types of defects present a certain anisotropy. Additionally, smaller micropores and microcracks are beyond the μCT detection ability.

Keywords

• selective laser melting
• gh3536 alloy
• defect
• anisotropy
• molten pool