This work pertains to research conducted by Milwaukee School of Engineering’s mechanical engineering undergraduate students under Dr. Kumpaty’s advisement on metal parts additively manufactured on a novel laser wire metal deposition ADDere system built by a local company, Midwest Engineered Systems, Inc. While many biocompatible metal parts were produced at MWES, samples were prepared and tested at the Materials Lab at Milwaukee School of Engineering. This research provided advisory guidelines to the manufacturing process based on the material characterization studies that were conducted and the goal was to optimize the build parameters for the system in producing parts that would comply with ASTM standards.

Several tests were conducted on 316 stainless steel, and 17-4 PH stainless steel to understand the effect of additive manufacturing on their mechanical properties in general. The 316 stainless steel is ideally suited for applications requiring corrosion resistance and has good elevated temperature strength when compared to type 304. The 17-4 stainless steel is the most widely used precipitation hardening stainless steel, and it is generally castoff in aerospace, chemical, petrochemical, and metalworking industries. The samples described in this paper were produced with variable laser power of 3600W for 316 stainless, and 4000W for 17-4 PH, but all other printing parameters were kept similar. To characterize the mechanical properties of these additively manufactured samples, four different tests, Tensile, Rockwell hardness, Charpy impact, and optical microscopy were carried out to establish the material properties and surface characterization. Through our assessment, it was found that the properties of the laser-printed samples can be greatly varied by printing in an inert atmosphere, while the printing orientation and post-print heat treatment process also play a dominant role in determining the properties. This research showed that the properties of additively manufactured 316 stainless, and 17-4 PH have fared well when compared to ASM standard values for annealed metals.  Details of the results will be presented.

Inspecting into 316 stainless, the metal strength and hardness were high while being printed in x orientation, while the metal was much more ductile when printed in y orientation. The 316 stainless microstructure contained no porosity or no anomalies from the samples tested.  The results of 17-4 stainless samples matched the ASTM standard values for strength and hardness. But with Charpy impact tests, the results seemed slightly ductile as the values were slightly lower than the threshold. That brittle nature could have been a result of porosity that was visible under microscope. But the porosity levels decreased tremendously when the sample was once again printed in an inert environment. The results of this research have helped us understand the intricate nature of 316 and 17-4 PH stainless steels while being additively printed.

 


Characterizing Additively Manufactured Metals From a Novel Laser Wire Metal Deposition Process

Division / Sponsors: 
Aerospace, Bioengineering, Applied Mechanics, Design Engineering Division, Advanced Energy Systems, Manufacturing Engineering Division, Noise Control and Acoustics, Nondestructive Evaluation, Diagnosis, and Prognosis (NDPD), Nuclear Engineering Division, Process Industries Division, Fluids Engineering, Heat Transfer, Materials, Microelectromechanical Systems, Safety Engineering and Risk Analysis, Computers & Information in Engineering


Paper Proceedings: https://asmedigitalcollection.asme.org/IMECE/IMECE2020/volume/84478

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