Characterization and Qualification of LPBF Additively Manufactured AISI-316L Stainless Steel Brackets for Aerospace Application

Abstract

Additive manufacturing or 3D printing is recognized as a revolutionary type of processing to replace the traditionally fabricated components, including castings, wrought products and multiple piece assemblies thereof. 3D printing helps to realize complicated parts within a short time, with minimum material wastage and allowing higher level of design optimization. Two types of brackets in stainless steel AISI-316L grade for aerospace applications were realized through laser powder bed fusion method. Detailed characterization, analysis and structural testing were performed on the powder, test coupons and the component itself to qualify these brackets for the intended application. Significant amount of material removal, excessive machining time and associated problems such as residual stresses and warpage envisaged in the conventional manufacturing route have been avoided. The mechanical properties meet the requirements specified in ASTM F 3184-16 standard and were similar to or better than vis-a-vis that can be achieved through forged route manufacturing. Minor distortion was noticed on thin wall regions which have been avoided in the next hardware by distortion compensation and adding extra stock at thin sections which can be removed by minimum machining. Non-destructive testing was performed by macro CT and brackets were found to be free from defects > 100 µm. Further, there is scope for topology optimization through design for additive manufacturing (DfAM) and achieving weight savings for future requirements.