Impact properties of AISI 316L stainless steel repaired by Directed Energy Deposition (DED) additive manufacturing process

Abstract

Directed Energy Deposition (DED) is considered as one of the potential processes for metallic structural repairs. In this work, the impact properties of the repaired stainless steel 316L were investigated. The repair was performed by depositing commercially available stainless steel 316L metal powder on the stainless steel 316L substrate using the DED process (LENS@ process). Strong bonding between the deposited layers and substrate and also between the layers in the deposited zone was observed under the proper selection and optimization of processing parameters. Results showed that the microstructure of the repaired zone generally consists of columnar and equiaxed grain structure. Heat Affected Zone (HAZ) provided the highest microhardness about 218HV, whereas the microhardness of the repaired zone and substrate was within the ranges of 192-209HV and 168-198HV, respectively. The impact properties of the repaired specimens were compared with the wrought stainless steel 316L (as-received). The average impact energy absorbed by the as-received specimens was higher than the repaired specimens. Moreover, the impact energy absorbed by the AM (subsize) and repaired (subsize) specimen were compared with the as-received specimens. The fractured surface morphology of both repaired and as-received specimens was also studied.