Abstract
In this work, the microstructural features and mechanical properties of an additively manufactured 316L stainless steel have been determined. Three types of samples were characterized: (i) as printed (AP), (ii) annealing heat treated (AHT), and (iii) hot isostatic pressed and annealing heat treated (HIP + AHT). Microstructural analysis reveals that the AP sample formed melt pool boundaries with nano-scale cellular structures. These structures disappeared after annealing heat treatment and hot isostatic pressing. The AP and AHT samples have similar grain morphologies; however, the latter has a lower dislocation density and contains precipitates. Conversely, the HIP + AHT sample displays polygon-shaped grains with twin structures; a completely different morphology compared to the first two samples. Optical micrography reveals that the application of hot isostatic pressing reduces the porosity generated after laser processing. The tensile strengths of all the samples are comparable (about 600 MPa); however, the elongation of the HIP + AHT sample (48%) was superior to that of other two samples. The enhanced ductility of the HIP + AHT sample, however, resulted in lower yield strength. Based on these findings, annealing heat treatment after hot isostatic pressing was found to improve the ductility of as-printed 316L stainless steel by as much as 130%, without sacrificing tensile strength, but the sample may have a reduced (40%) yield strength. The tensile strength determined here has been shown to be higher than that of the hot isostatic pressed, additively manufactured 316L stainless steel available from the literature.
Highlights
Additive manufacturing (AM) technology is a layer-by-layer deposition technique to form a solid material using a computerized three-dimensional model [1]
The goal of this work is to understand the effect of annealing heat treatment (AHT) after the hot isostatic pressing (HIP) of additively manufactured 316L stainless steel
Samples of 316L stainless steel used in this study were manufactured and supplied by the voestalpine Additive Manufacturing Center Ltd., Mississauga, ON, Canada
Summary
Additive manufacturing (AM) technology is a layer-by-layer deposition technique to form a solid material using a computerized three-dimensional model [1]. The integration of this technology with various commercial applications represents one of the innovations of Industry 4.0 [2]. There are numerous types of AM [4], laser powder bed fusion (LPBF) is one of the most common techniques being explored. The method employs a laser gun to selectively melt metallic powders in a layer-by-layer fashion until a final product is achieved. AM products currently produced by LPBF have a wide range of applications in the aerospace, defense, automotive, medical, and oil and gas sectors
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
