In Situ Characterization of Hot Cracking Using Dynamic X-Ray Radiography

  • Po-Ju Chiang
  • Runbo Jiang
  • Ross Cunningham
  • Niranjan Parab
  • Cang Zhao
  • Kamel Fezzaa
  • Tao Sun
  • Anthony D. RollettEmail author
Conference paper
Part of the The Minerals, Metals & Materials Series book series (MMMS)


We employ dynamic X-ray radiography (DXR) for in situ and real-time characterization of the hot cracking phenomenon for aluminum alloy 6061 under the processing conditions typical of laser powder bed fusion. The dynamics of processes such as a crack initiating from a bubble trapped subsurface are captured. We also directly observe the backfilling of liquid that heals an open crack. In addition, we demonstrate the feasibility of determining the point of origin for hot cracking with a temporal resolution of order 20 µs and spatial resolution of order 2 µm. This could shed light on the estimation of solid fraction at the initiation of hot cracking, which is a critical parameter upon which many models are based. We demonstrate the capability of DXR for generating new insights into verify or refine hot cracking models, and understand this problem fundamentally, which could ultimately lead to the optimization of process control for additive manufacturing.


Hot cracking Dynamic X-ray radiography Additive manufacturing 


  1. 1.
    Eskin DG, Katgerman L (2004) Mechanical properties in the semi-solid state and hot tearing of aluminium alloys. Prog Mater Sci 49(5): 629–711CrossRefGoogle Scholar
  2. 2.
    Kou S (2015) A criterion for cracking during solidification. Acta Mater 88:366–374CrossRefGoogle Scholar
  3. 3.
    Martin JH, Yahata BD, Hundley JM, Mayer JA, Schaedler TA, Pollock TM (2017) 3D printing of high-strength aluminium alloys. Nature 549(7672):365CrossRefGoogle Scholar
  4. 4.
    Kou S (2003) Solidification and liquation cracking issues in welding. J Miner Metals Mater Soc 55(6):37–42CrossRefGoogle Scholar
  5. 5.
    Easton MA, Wang H, Grandfield J, Davidson CJ, Stjohn DH, Sweet LD, Couper MJ (2012) Observation and prediction of the hot tear susceptibility of ternary Al–Si–Mg alloys. Metall Mater Trans A 43A(9):3227–3238CrossRefGoogle Scholar
  6. 6.
    Rappaz, M, Drezet, JM, Gremaud, M (1999) A new hot-tearing criterion. Metall Mater Trans A 30(2):449–455CrossRefGoogle Scholar
  7. 7.
    Jackson KA, Hunt JD (1965) Transparent compounds that freeze like metals. J Metals 17(9):1031Google Scholar
  8. 8.
    Fukuhisa M, Hiroji N, Kazuhiko S (1982) Dynamic observation of solidification and solidification cracking during welding with optical microscope (I): solidification front and behavior of cracking (materials, metallurgy & weldability), transactions of JWRIGoogle Scholar
  9. 9.
    Nguyen-Thi H, Salvo L, Mathiesen RH, Arnberg L, Billia B, Suery M, Reinhart G (2012) On the interest of synchrotron X-ray imaging for the study of solidification in metallic alloys. Comptes Rendus Phys 13(3):237–245CrossRefGoogle Scholar
  10. 10.
    Zhao C, Fezzaa K, Cunningham RW, Wen HD, De Carlo F, Chen LY, Rollett AD, Sun T (2017) Real-time monitoring of laser powder bed fusion process using high-speed X-ray imaging and diffraction. Sci Rep 7:11CrossRefGoogle Scholar
  11. 11.
    Mathiesen RH, Arnberg L (2005) X-ray radiography observations of columnar dendritic growth and constitutional undercooling in an Al–30 wt%Cu alloy. Acta Mater 53(4):947–956CrossRefGoogle Scholar
  12. 12.
    Cunningham R, Nicolas A, Madsen J, Fodran E, Anagnostou E, Sangid MD, Rollett AD (2017) Analyzing the effects of powder and post-processing on porosity and properties of electron beam melted Ti–6Al–4V. Mater Res Lett 5(7):516–525CrossRefGoogle Scholar
  13. 13.
    Puncreobutr C, Phillion AB, Fife JL, Rockett P, Horsfield AP, Lee PD (2014) In situ quantification of the nucleation and growth of Fe-rich intermetallics during Al alloy solidification. Acta Mater 79:292–303CrossRefGoogle Scholar
  14. 14.
    Terzi S, Taylor JA, Cho YH, Salvo L, Suery M, Boller E, Dahle AK (2010) In situ study of nucleation and growth of the irregular alpha-Al/beta-Al5FeSi eutectic by 3-D synchrotron X-ray microtomography. Acta Mater 58(16):5370–5380CrossRefGoogle Scholar
  15. 15.
    Reinhart G, Buffet A, Nguyen-Thi H, Billia B, Jung H, Mangelinck-Noel N, Bergeon N, Schenk T, Hartwig J, Baruchel J (2008) In-situ and real-time analysis of the formation of strains and microstructure defects during solidification of Al–3.5 wt pct Ni alloys. Metall Mater Trans A 39A(4): 865–874CrossRefGoogle Scholar
  16. 16.
    Sun T, Fezzaa K (2016) HiSPoD: a program for high-speed polychromatic X-ray diffraction experiments and data analysis on polycrystalline samples. J Synchrotron Radiat 23:1046–1053CrossRefGoogle Scholar
  17. 17.
    Parab ND, Zhao C, Cunningham R, Escano LI, Fezzaa K, Everhart W, Rollett AD, Chen L, Sun T (2018) Ultrafast X-ray imaging of laser–metal additive manufacturing processes. J Synchrotron Radiat 25(5):1467–1477CrossRefGoogle Scholar
  18. 18.
    Lippold JC (2015) Welding metallurgy and weldability, welding metallurgy and weldability, pp 1–400CrossRefGoogle Scholar
  19. 19.
    Liu JW, Duarte HP, Kou S (2017) Evidence of back diffusion reducing cracking during solidification. Acta Mater 122:47–59CrossRefGoogle Scholar

Copyright information

© The Minerals, Metals & Materials Society 2019

Authors and Affiliations

  • Po-Ju Chiang
    • 1
  • Runbo Jiang
    • 1
  • Ross Cunningham
    • 1
  • Niranjan Parab
    • 2
  • Cang Zhao
    • 2
  • Kamel Fezzaa
    • 2
  • Tao Sun
    • 2
  • Anthony D. Rollett
    • 1
    Email author
  1. 1.Department of Materials Science and EngineeringCarnegie Mellon UniversityPittsburghUSA
  2. 2.X-Ray Science Division, Advanced Photon SourceArgonne National LaboratoryArgonneUSA

Personalised recommendations