Additive manufacturing has many positives, but its incorporation into functional parts production is restricted by the presence of defects. Eddy current testing provides solutions for their identification; however, some methodology and measurement standards for AM (additive manufacturing) products are still missing. The main purpose of the experiment described within this article was to check the ability of eddy current testing to identify AM stainless steel parts and to examine the data obtained by eddy currents variation under the influence of various types of designed artificial defects. Experimental samples were designed and prepared with SLM (selective laser melting) technology. Artificial defects, included in the samples, were detected using the eddy current testing device, taking the important circumstances of this non-destructive method into account. The presented research shows significant potential for eddy current testing to identify defects in AM products, with a resolution of various types and sizes of defects. The obtained data output shows the importance of choosing the right measurement regime, excitation frequency and secondary parameters setup. Besides the eddy current testing conditions, defect properties also play a significant role, such as their shape, size, if they are filled with unmolten powder or if they reach the surface.

Center of 3D Printing Protolab Department of Machining Assembly and Engineering Technology Faculty of Mechanical Engineering VSB TU Ostrava 17 Listopadu 2172 15 708 00 Ostrava Czech Republic

Faculty of Manufacturing Technologies Technical University of Košice with Seat in Prešov 080 01 Prešov Slovakia

Zobrazit více v PubMed

Wong K.V., Hernandez A. A review of additive manufacturing. Int. Sch. Res. Not. 2012;2012:208760. doi: 10.5402/2012/208760. DOI

Frazier W.E. Metal additive manufacturing: A review. J. Mater. Eng. Perform. 2014;23:1917–1928. doi: 10.1007/s11665-014-0958-z. DOI

Despa V., Gheorghe I.G. Study of selective laser sintering: A qualitative and objective approach. Sci. Bull. Valahia Univ. Mater. Mech. 2011;6:150–155.

Kellens K., Yasa E., Dewulf W., Duflou J.R. Environmental assessment of selective laser melting and selective laser sintering. Methodology. 2010;4:1–8.

Röttger A., Boes J., Theisen W., Thiele M., Esen C., Edelmann A., Hellmann R. Microstructure and mechanical properties of 316L austenitic stainless steel processed by different SLM devices. Int. J. Adv. Manuf. Technol. 2020;108:769–783. doi: 10.1007/s00170-020-05371-1. DOI

Dong Z., Liu Y., Wen W., Ge J., Liang J. Effect of hatch spacing on melt pool and as-built quality during selective laser melting of stainless steel: Modeling and experimental approaches. Materials. 2018;12:50. doi: 10.3390/ma12010050. PubMed DOI PMC

Marattukalam J.J., Karlsson D., Pacheco V., Beran P., Wiklund U., Jansson U., Hjörvarsson B., Sahlberg M. The effect of laser scanning strategies on texture, mechanical properties, and site-specific grain orientation in selective laser melted 316L SS. Mater. Des. 2020;193:108852. doi: 10.1016/j.matdes.2020.108852. DOI

Chen J., Yang Y., Song C., Zhang M., Wu S., Wang D. Interfacial microstructure and mechanical properties of 316L/CuSn10 multi-material bimetallic structure fabricated by selective laser melting. Mater. Sci. Eng. A. 2019;752:75–85. doi: 10.1016/j.msea.2019.02.097. DOI

Kaynak Y., Kitay O. The effect of post-processing operations on surface characteristics of 316L stainless steel produced by selective laser melting. Addit. Manuf. 2019;26:84–93. doi: 10.1016/j.addma.2018.12.021. DOI

Fu J., Li H., Song X., Fu M. Multi-scale defects in powder-based additively manufactured metals and alloys. J. Mater. Sci. Technol. 2022;122:165–199. doi: 10.1016/j.jmst.2022.02.015. DOI

Malekipour E., El-Mounayri H. Common defects and contributing parameters in powder bed fusion AM process and their classification for online monitoring and control: A review. Int. J. Adv. Manuf. Technol. 2018;95:527–550. doi: 10.1007/s00170-017-1172-6. DOI

Gu D., Shen Y. Balling phenomena in direct laser sintering of stainless steel powder: Metallurgical mechanisms and control methods. Mater. Des. 2009;30:2903–2910. doi: 10.1016/j.matdes.2009.01.013. DOI

Gong H., Rafi K., Gu H., Starr T., Stucker B. Analysis of defect generation in Ti–6Al–4V parts made using powder bed fusion additive manufacturing processes. Addit. Manuf. 2014;1:87–98. doi: 10.1016/j.addma.2014.08.002. DOI

Hauser C. Ph.D. Thesis. University of Leeds; Leeds, UK: Jul, 2003. Selective Laser Sintering of a Stainless Steel Powder.

Liu Y., Yang Y., Wang D. A study on the residual stress during selective laser melting (SLM) of metallic powder. Int. J. Adv. Manuf. Technol. 2016;87:647–656. doi: 10.1007/s00170-016-8466-y. DOI

Zhang X., Xiao Z., Yu W., Chua C.K., Zhu L., Wang Z., Xue P., Tan S., Wu Y., Zheng H. Influence of erbium addition on the defects of selective laser-melted 7075 aluminium alloy. Virtual Phys. Prototyp. 2022;17:406–418. doi: 10.1080/17452759.2021.1990358. DOI

Chen H., Gu D., Deng L., Lu T., Kühn U., Kosiba K. Laser additive manufactured high-performance Fe-based composites with unique strengthening structure. J. Mater. Sci. Technol. 2021;89:242–252. doi: 10.1016/j.jmst.2020.04.011. DOI

Romano S., Nezhadfar P., Shamsaei N., Seifi M., Beretta S. High cycle fatigue behavior and life prediction for additively manufactured 17-4 PH stainless steel: Effect of sub-surface porosity and surface roughness. Theor. Appl. Fract. Mech. 2020;106:102477. doi: 10.1016/j.tafmec.2020.102477. DOI

Li S., Wei Q., Shi Y., Zhu Z., Zhang D. Microstructure characteristics of Inconel 625 superalloy manufactured by selective laser melting. J. Mater. Sci. Technol. 2015;31:946–952. doi: 10.1016/j.jmst.2014.09.020. DOI

Fergani O., Berto F., Welo T., Liang S.Y. Analytical modelling of residual stress in additive manufacturing. Fatigue Fract. Eng. Mater. Struct. 2017;40:971–978. doi: 10.1111/ffe.12560. DOI

Slotwinski J.A., Garboczi E.J., Hebenstreit K.M. Porosity measurements and analysis for metal additive manufacturing process control. J. Res. Natl. Inst. Stand. Technol. 2014;119:494–528. doi: 10.6028/jres.119.019. PubMed DOI PMC

Dai T., Jia X.-J., Zhang J., Wu J.-F., Sun Y.-W., Yuan S.-X., Ma G.-B., Xiong X.-J., Ding H. Laser ultrasonic testing for near-surface defects inspection of 316L stainless steel fabricated by laser powder bed fusion. China Foundry. 2021;18:360–368. doi: 10.1007/s41230-021-1063-1. DOI

Zhan Y., Liu C., Zhang J.J., Mo G.Z., Liu C.S. Measurement of residual stress in laser additive manufacturing TC4 titanium alloy with the laser ultrasonic technique. Mater. Sci. Eng. A. 2019;762:138093. doi: 10.1016/j.msea.2019.138093. DOI

Ito K., Kusano M., Demura M., Watanabe M. Detection and location of microdefects during selective laser melting by wireless acoustic emission measurement. Addit. Manuf. 2021;40:101915. doi: 10.1016/j.addma.2021.101915. DOI

Biddle C.C. Theory of Eddy Currents for Nondestructive Testing. Retrosp. Theses Diss. 1976;201:1–84.

He Y., Luo F., Pan M., Weng F., Hu X., Gao J., Liu B. Pulsed eddy current technique for defect detection in aircraft riveted structures. NDT E Int. 2010;43:176–181. doi: 10.1016/j.ndteint.2009.10.010. DOI

Förster F. Sensitive eddy-current testing of tubes for defects on the inner and outer surfaces. Non-Destr. Test. 1974;7:28–36. doi: 10.1016/0029-1021(74)90023-1. DOI

Fukutomi H., Huang H., Takagi T., Tani J. Identification of crack depths from eddy current testing signal. IEEE Trans. Magn. 1998;34:2893–2896. doi: 10.1109/20.717674. DOI

Bowler N., Huang Y. Electrical conductivity measurement of metal plates using broadband eddy-current and four-point methods. Meas. Sci. Technol. 2005;16:2193–2200. doi: 10.1088/0957-0233/16/11/009. DOI

Wang Z., Yu Y. Thickness and conductivity measurement of multilayered electricity-conducting coating by pulsed eddy current technique: Experimental investigation. IEEE Trans. Instrum. Meas. 2018;68:3166–3172. doi: 10.1109/TIM.2018.2872386. DOI

Abdou A., Bouchala T., Abdelhadi B., Guettafi A., Benoudjit A. Nondestructive Eddy Current Measurement of Coating Thickness of Aeronautical Construction Materials. Instrum. Mes. Métrol. 2019;18:451–457. doi: 10.18280/i2m.180504. DOI

Ricken W., Liu J., Becker W.J. GMR and eddy current sensor in use of stress measurement. Sens. Actuators A Phys. 2001;91:42–45. doi: 10.1016/S0924-4247(01)00479-4. DOI

Botko F., Zajac J., Czan A., Radchenko S., Lehocka D., Duplak J. Influence of residual stress induced in steel material on Eddy currents response parameters; Proceedings of the International Scientific-Technical Conference MANUFACTURING; Poznan, Poland. 19–22 May 2019.

García-Martín J., Gómez-Gil J., Vázquez-Sánchez E. Non-destructive techniques based on eddy current testing. Sensors. 2011;11:2525–2565. doi: 10.3390/s110302525. PubMed DOI PMC

Du W., Bai Q., Wang Y., Zhang B. Eddy current detection of subsurface defects for additive/subtractive hybrid manufacturing. Int. J. Adv. Manuf. Technol. 2018;95:3185–3195. doi: 10.1007/s00170-017-1354-2. DOI

Guo S., Ren G., Zhang B. Subsurface Defect Evaluation of Selective-Laser-Melted Inconel 738LC Alloy Using Eddy Current Testing for Additive/Subtractive Hybrid Manufacturing. Chin. J. Mech. Eng. 2021;34:111. doi: 10.1186/s10033-021-00633-9. DOI

Obaton A.-F., Lê M.-Q., Prezza V., Marlot D., Delvart P., Huskic A., Senck S., Mahé E., Cayron C. Investigation of new volumetric non-destructive techniques to characterise additive manufacturing parts. Weld. World. 2018;62:1049–1057. doi: 10.1007/s40194-018-0593-7. DOI

Kobayashi N., Yamamoto S., Sugawara A., Nakane M., Tsuji D., Hino T., Terada T., Ochiai M. Fundamental experiments of eddy current testing for additive manufacturing metallic material toward in-process inspection. AIP Conf. Proc. 2019;2102:070003.

Özer G., Tarakçi G., Yilmaz M.S., Öter Z.Ç., Sürmen Ö., Akça Y., Coşkun M., Koç E. Investigation of the effects of different heat treatment parameters on the corrosion and mechanical properties of the AlSi10Mg alloy produced with direct metal laser sintering. Mater. Corros. 2020;71:365–373. doi: 10.1002/maco.201911171. DOI

Ehlers H., Pelkner M., Thewes R. Heterodyne eddy current testing using magnetoresistive sensors for additive manufacturing purposes. IEEE Sens. J. 2020;20:5793–5800. doi: 10.1109/JSEN.2020.2973547. DOI

Duarte V.R., Rodrigues T.A., Machado M.A., Pragana J.P., Pombinha P., Coutinho L., Silva C.M., Miranda R.M., Goodwin C., Huber D.E., et al. Benchmarking of nondestructive testing for additive manufacturing. 3d Print. Addit. Manuf. 2021;8:263–270. doi: 10.1089/3dp.2020.0204. PubMed DOI PMC

Stoll P., Gasparin E., Spierings A., Wegener K. Embedding eddy current sensors into LPBF components for structural health monitoring. Prog. Addit. Manuf. 2021;6:445–453. doi: 10.1007/s40964-021-00204-3. DOI

E Farag H., Toyserkani E., Khamesee M.B. Non-Destructive Testing Using Eddy Current Sensors for Defect Detection in Additively Manufactured Titanium and Stainless-Steel Parts. Sensors. 2022;22:5440. doi: 10.3390/s22145440. PubMed DOI PMC

D’Accardi E., Krankenhagen R., Ulbricht A., Pelkner M., Pohl R., Palumbo D., Galietti U. Capability to detect and localize typical defects of laser powder bed fusion (L-PBF) process: An experimental investigation with different non-destructive techniques. Prog. Addit. Manuf. 2022:1–18. doi: 10.1007/s40964-022-00297-4. DOI

Center of 3D Printing Protolab. [(accessed on 3 August 2022)]. Available online: https://protolab.cz.

Data Sheet: SS 316L-0407 Powder for Additive Manufacturing. [(accessed on 3 August 2022)]. Available online: https://www.renishaw.com/resourcecentre/en/details/data-sheet-ss-316l-0407-powder-for-additive-manufacturing--90802.

NORTEC 600 Eddy Current Flaw Detector User’s Manual. [(accessed on 3 August 2022)]. Available online: https://manualzz.com/doc/59581713/olympus-nortec-600-user-manual.

AISI Type 316L Stainless Steel. [(accessed on 3 August 2022)]. Available online: https://www.matweb.com/search/DataSheet.aspx?MatGUID=a2d0107bf958442e9f8db6dc9933fe31.

304 Stainless Steel. [(accessed on 3 August 2022)]. Available online: https://www.matweb.com/search/DataSheet.aspx?MatGUID=abc4415b0f8b490387e3c922237098da.

Aluminum 7075-T6. [(accessed on 3 August 2022)]. Available online: https://www.matweb.com/search/DataSheet.aspx?MatGUID=4f19a42be94546b686bbf43f79c51b7d.