This paper summarizes the assessment of directional anisotropy in local mechanical properties for Laser Powder Bed Fusion (LPBF) IN-718 bulk samples via the use of miniature samples excised from the bulk for both as-deposited and post-treated states. The quasi-static tensile properties at room temperature are investigated at several different locations along the build direction and at different orientations for both considered states. A comparison between the excised miniature tensile specimens and standard-sized sample results have also been conducted and exhibit very good agreement. Significant anisotropy is present in mechanical properties at different build heights for the as-deposited state, while the post-treated material exhibited more homogenous properties, both along the height and for different sampling orientations. However, significant reductions (e.g., >30%) in the strength (Yield, UTS) along with a significant increase in the reduction in area at fracture is found for post-processed materials. Metallography and fractography analyses were conducted in order to begin to determine the source(s) of this anisotropy for the as-deposited state.

ASTM International Washington DC 20036 USA

Beehive 3D Inc Deerfield Beach FL 33442 USA

COMTES FHT a s Prumyslova 995 33441 Dobrany Czech Republic

Department of Materials Science and Engineering Case Western Reserve University Cleveland OH 4163 USA

See more in PubMed

Lewandowski J.J., Seifi M. Metal Additive Manufacturing: A Review of Mechanical Properties. Annu. Rev. Mater. 2016;46:151–186. doi: 10.1146/annurev-matsci-070115-032024. DOI

Palanivel S., Dutt A.K., Faierson E.J., Mishra R.S. Spatially dependent properties in a laser additive manufactured Ti–6Al–4V component. Mater. Sci. Eng. A. 2016;654:39–52. doi: 10.1016/j.msea.2015.12.021. DOI

Melzer D., Džugan J., Koukolíková M., Rzepa S., Vavřík J. Structural integrity and mechanical properties of the functionally graded material based on 316L/IN718 processed by DED technology. Mater. Sci. Eng. A. 2021;811:141038. doi: 10.1016/j.msea.2021.141038. DOI

Popovich V.A., Borisov E.V., Popovich A.A., Sufiiarov V.S., Masaylo D.V., Alzina L. Functionally graded Inconel 718 processed by additive manufacturing: Crystallographic texture, anisotropy of microstructure and mechanical properties. Mater. Des. 2017;114:441–449. doi: 10.1016/j.matdes.2016.10.075. DOI

Máthis K., Köver M., Stráská J., Džugan J., Halmešová K. Micro-tensile behavior of Mg-Al-Zn alloy processed by equal channel angular pressing (ECAP) Materials. 2018;11:1644. doi: 10.3390/ma11091644. PubMed DOI PMC

Chlebus E., Gruber K., Kuznicka B., Kurzac J., Kurzynowski T. Effect of heat treatment on the microstructure and mechanical properties of Inconel 718 processed by selective laser melting. Mater. Sci. Eng. A-Struct. Mater. Prop. 2015;639:647–655. doi: 10.1016/j.msea.2015.05.035. DOI

Džugan J., Prochazka R., Konopik P. Micro-Tensile Test Technique Development and Application to Mechanical Property Determination. Volume STP 1576 ASTM Special Technical Publication; West Conshohocken, PA, USA: 2015.

Džugan J., Konopik P., Rund M., Prochazka R. Pressure Vessels and Piping Division (VP) Volume 1A American Society of Mechanical Engineers; New York, NY, USA: 2015. Determination of local tensile and fatigue properties with the use of sub-sized specimens.

Procházka R., Džugan J. Low cycle fatigue properties assessment for rotor steels with the use of miniaturized specimens. Int. J. Fatigue. 2022;154:106555. doi: 10.1016/j.ijfatigue.2021.106555. DOI

Dzugan J., Sibr M., Konopík P., Procházka R., Rund M. Mechanical properties determination of AM components; Proceedings of the 4th International Conference Recent Trends in Structural Materials; Pilsen, Czech Republic. 9–11 November 2016; pp. 1–7.

Konopík P., Džugan J., Rund M. Dynamic tensile and micro-tensile testing using DIC method; Proceedings of the METAL 2014—23rd International Conference on Metallurgy and Materials, sv.; Brno, Czech Republic. 21–23 May 2014.

Standard Guide for Orientation and Location Dependence Mechanical Properties for Metal Additive Manufacturing. ASTM International; West Conshohocken, PA, USA: 2017.

Kohyama A., Hamada K., Matsui H. Specimen size effects on tensile properties of neutron-irradiated steels. J. Nucl. Mater. 1991;179:417–420. doi: 10.1016/0022-3115(91)90113-L. DOI

Kohno Y., Kohyama A., Hamilton M.L., Hirose T., Katoh Y., Garner F.A. Specimen size effects on the tensile properties of JPCA and JFMS. J. Nucl. Mater. 2000;283:1014–1017. doi: 10.1016/S0022-3115(00)00245-2. DOI

Gussev M.N., Busby J.T., Field K.G., Sokolov M.A., Gray S.E. Role of Scale Factor during Tensile Testing of Small Specimens. Volume STP 1576. ASTM Special Technical Publication; West Conshohocken, PA, USA: 2015. pp. 31–49.

Kumar K., Pooleery A., Madhusoodanan K., Singh R.N., Chakravartty J.K., Dutta B.K., Sinha R.K. Use of miniature tensile specimen for measurement of mechanical properties. Procedia Eng. 2014;86:899–909. doi: 10.1016/j.proeng.2014.11.112. DOI

Zhang J., Chu D. Mechanical characterization of post-buckled micro-bridge beams by micro-tensile testing. Microsyst. Technol. 2010;16:375–380. doi: 10.1007/s00542-009-0934-y. DOI

Yuan W., Zhang W., Su Z., Qiao Y., Chu L. Influence of specimen thickness with rectangular cross-section on the tensile properties of structural steels. Mater. Sci. Eng. A. 2012;532:601–605. doi: 10.1016/j.msea.2011.11.021. DOI

Wang G., Wang C., Guo C., Shan B., Huang D. Size effect on flow stress in uniaxial compression of pure nickel cylinders with a few grains across thickness. Mater. Lett. 2013;106:294–296. doi: 10.1016/j.matlet.2013.05.037. DOI

Poling W.A. Grain Size Effects in Micro-Tensile Testing of Austenitic Stainless Steel. Colorado School of Mines; Golden, CO, USA: 2012.

Henning H., Vehoff M. Statistical size effects based on grain size and texture in thin sheets. Mater. Sci. Eng. A. 2017;452:603–613. doi: 10.1016/j.msea.2006.11.113. DOI

Brandt M. Laser Additive Manufacturing: Materials, Design, Technologies and Applications. Elsevier Ltd.; Amsterdam, The Netherlands: 2017.

Moore P. Nondestructive Testing Handbook: Volume 4. Radiographic Testing. 3rd ed. American Society for Nondestructive Testing; Columbus, OH, USA: 2002.