Ultrasonic non-destructive characterization of hybrid additively manufactured 420 stainless steel made with directed energy deposition

Abstract

Additive manufacturing is remarkably suitable for creating high complexity performance parts. An added benefit of the Directed Energy Deposition (DED) process is the ability to make functionally graded materials. This expansion of the design and manufacturing spaces presents a challenge for the non-destructive evaluation of AM parts. Hybrid AM parts are an example of functionally graded materials for which the variation in microstructure and material properties across the bulk of the parts is created through a combination of manufacturing processes. In this work, a hybrid 420 stainless steel coupon was created using the DED method, and a surface treatment was applied between added layers. Characterization using destructive and non-destructive methods was performed. The microstructure, hardness profile, phase velocity, attenuation, and backscatter results from the hybrid coupon are compared with those from an AM coupon and a wrought coupon. Agreement between destructive and non-destructive measurements is studied. Furthermore, ultrasonic non-destructive methods are shown to be effective for identifying the gradient in the material properties of the hybrid coupon. The work hereby presented can further inform non-destructive evaluation decisions for hybrid AM parts.Additive manufacturing is remarkably suitable for creating high complexity performance parts. An added benefit of the Directed Energy Deposition (DED) process is the ability to make functionally graded materials. This expansion of the design and manufacturing spaces presents a challenge for the non-destructive evaluation of AM parts. Hybrid AM parts are an example of functionally graded materials for which the variation in microstructure and material properties across the bulk of the parts is created through a combination of manufacturing processes. In this work, a hybrid 420 stainless steel coupon was created using the DED method, and a surface treatment was applied between added layers. Characterization using destructive and non-destructive methods was performed. The microstructure, hardness profile, phase velocity, attenuation, and backscatter results from the hybrid coupon are compared with those from an AM coupon and a wrought coupon. Agreement between destructive and non-destructive measurements is ...