Advertisement

An experimental investigation of surface integrity in selective laser melting of Inconel 625

  • M. A. BalbaaEmail author
  • M. A. ElbestawiEmail author
  • J. McIsaac
ORIGINAL ARTICLE
  • 242 Downloads

Abstract

Inconel 625 is a Ni-based superalloy widely used in nuclear and aerospace applications because of its high strength and corrosion resistance. The current paper investigates selective laser melting of Inconel 625 using a wide range of process parameters: four laser powers, five scan speeds, and three hatch spacings. Cube coupons are produced and their end properties are measured, specifically, relative density, surface roughness, microhardness, and surface residual stresses. Process maps are constructed to correlate processing parameters to the part surface integrity, and the possible underlying causes are highlighted. Experimental results show that highly dense parts can be produced using selective laser melting and low average surface roughness can be obtained in both the scan and hatch directions. Hatch spacing is the most prominent factor to attain relative densities above 99% while high laser powers are key to lower the average surface roughness. Microhardness and microstructure examination are done for a subset of the process parameters and found to not significantly change with laser power. Surface residual stresses are measured on the top surface in the scan and hatch directions and process maps are developed. There is no particular parameter that solely affects surface residual stresses, despite several cases where the increase in laser power reduced the surface residual stresses. 90% of measurements showed surface tensile residual stresses except for a few cases that resulted in surface compressive residual stress.

Keywords

Selective laser melting Inconel 625 Density Surface roughness Residual stresses 

Acronyms

AM

Additive manufacturing

EDS

Energy-dispersive X-ray spectroscopy

FE

Finite element

HIP

Hot isostatic pressing

PSD

Particle size distribution

RS

Residual stress

SEM

Scanning electron microscope

SLM

Selective laser melting

Notations

Ed

Volumetric energy density (J/mm3)

E

Modulus of elasticity (MPa)

P

Laser power (W)

T

Temperature (0K)

h

Hatch spacing (mm)

t

Layer thickness (mm)

v

Scan speed (mm/s)

α

Coefficient of thermal expansion (0K -1)

ρ

Density (kg/m3)

σth

Thermal stresses (MPa)

τs

Molten droplet solidification time (s)

Notes

References

  1. 1.
    I. ASTM, “ASTM52900-15 (2015) Standard terminology for additive manufacturing–general principles–terminology. ASTM International, West Conshohocken, PAGoogle Scholar
  2. 2.
    Gu D, Meiners W, Wissenbach K, Poprawe R (2012) Laser additive manufacturing of metallic components: materials, processes and mechanisms. Int Mater Rev 57:133–164Google Scholar
  3. 3.
    Frazier WE (2014) Metal additive manufacturing: a review. J Mater Eng Perform 23:1917–1928Google Scholar
  4. 4.
    B. Cheng, S. Shrestha, and Y. K. Chou, “Stress and deformation evaluations of scanning strategy effect in selective laser melting,” in ASME 2016 11th International Manufacturing Science and Engineering Conference, 2016, pp. V003T08A009-V003T08A009Google Scholar
  5. 5.
    Koutiri I, Pessard E, Peyre P, Amlou O, De Terris T (2018) Influence of SLM process parameters on the surface finish, porosity rate and fatigue behavior of as-built Inconel 625 parts. J Mater Process Technol 255:536–546Google Scholar
  6. 6.
    Marchese G, Garmendia Colera X, Calignano F, Lorusso M, Biamino S, Minetola P, Manfredi D (2017) Characterization and comparison of Inconel 625 processed by selective laser melting and laser metal deposition. Adv Eng Mater 19Google Scholar
  7. 7.
    Dinda G, Dasgupta A, Mazumder J (2009) Laser aided direct metal deposition of Inconel 625 superalloy: microstructural evolution and thermal stability. Mater Sci Eng A 509:98–104Google Scholar
  8. 8.
    Ezugwu E, Wang Z, Machado A (1999) The machinability of nickel-based alloys: a review. J Mater Process Technol 86:1–16Google Scholar
  9. 9.
    Criales LE, Arısoy YM, Lane B, Moylan S, Donmez A, Özel T (2017) Laser powder bed fusion of nickel alloy 625: experimental investigations of effects of process parameters on melt pool size and shape with spatter analysis. Int J Mach Tools Manuf 121:22–36Google Scholar
  10. 10.
    Criales LE, Arısoy YM, Lane B, Moylan S, Donmez A, Özel T (2017) Predictive modeling and optimization of multi-track processing for laser powder bed fusion of nickel alloy 625. Additive Manufacturing 13:14–36Google Scholar
  11. 11.
    Arısoy YM, Criales LE, Özel T, Lane B, Moylan S, Donmez A (2017) Influence of scan strategy and process parameters on microstructure and its optimization in additively manufactured nickel alloy 625 via laser powder bed fusion. Int J Adv Manuf Technol 90:1393–1417Google Scholar
  12. 12.
    Criales LE, Arısoy YM, Özel T (2016) Sensitivity analysis of material and process parameters in finite element modeling of selective laser melting of Inconel 625. Int J Adv Manuf Technol 86:2653–2666Google Scholar
  13. 13.
    M. A. Anam, D. Pal, and B. Stucker, 2013“Modeling and experimental validation of nickel-based super alloy (Inconel 625) made using selective laser melting,” in Solid Freeform Fabrication (SFF) Symposium, University of Texas at Austin, Austin, TX,, pp. 12–14Google Scholar
  14. 14.
    M. A. Anam, J. Dilip, D. Pal, and B. Stucker,2014 “Effect of scan pattern on the microstructural evolution of Inconel 625 during selective laser melting,” in Proceedings of 25th Annual International Solid Freeform Fabrication Symposium,Google Scholar
  15. 15.
    Carter LN, Wang X, Read N, Khan R, Aristizabal M, Essa K et al (2016) Process optimisation of selective laser melting using energy density model for nickel based superalloys. Mater Sci Technol 32:657–661Google Scholar
  16. 16.
    Beuth J, Klingbeil N (2001) The role of process variables in laser-based direct metal solid freeform fabrication. Jom 53:36–39Google Scholar
  17. 17.
    C. Montgomery, J. Beuth, L. Sheridan, and N. Klingbeil,2015 Process mapping of Inconel 625 in laser powder bed additive manufacturing, in Solid Freeform Fabrication Symposium, , pp. 1195–1204Google Scholar
  18. 18.
    Amato K, Hernandez J, Murr L, Martinez E, Gaytan S, Shindo P et al (2012) Comparison of microstructures and properties for a Ni-base superalloy (alloy 625) fabricated by electron beam melting. J Mater Sci Res 1:3Google Scholar
  19. 19.
    Li S, Wei Q, Shi Y, Zhu Z, Zhang D (2015) Microstructure characteristics of Inconel 625 superalloy manufactured by selective laser melting. J Mater Sci Technol 31:946–952Google Scholar
  20. 20.
    Li C, White R, Fang X, Weaver M, Guo Y (2017) Microstructure evolution characteristics of Inconel 625 alloy from selective laser melting to heat treatment. Mater Sci Eng A 705:20–31Google Scholar
  21. 21.
    Mumtaz K, Hopkinson N (2009) Top surface and side roughness of Inconel 625 parts processed using selective laser melting. Rapid Prototyp J 15:96–103Google Scholar
  22. 22.
    S. Raghavan, S. Chen-Nan, Z. Baicheng, S. W. Jack, P. Wang, N. M. L. Sharon, et al., 2015 Mechanical properties and microstructures of as printed and heat treated samples of selective laser melted IN625 alloy powder, in MATEC Web of Conferences,Google Scholar
  23. 23.
    D. B. Witkin, P. Adams, and T. Albright, 2015Microstructural evolution and mechanical behavior of nickel-based superalloy 625 made by selective laser melting,” in Laser 3D Manufacturing II, , p. 93530BGoogle Scholar
  24. 24.
    Hack H, Link R, Knudsen E, Baker B, Olig S (2017) Mechanical properties of additive manufactured nickel alloy 625. Additive Manufacturing 14:105–115Google Scholar
  25. 25.
    Kreitcberg A, Brailovski V, Turenne S (2017) Elevated temperature mechanical behavior of IN625 alloy processed by laser powder-bed fusion. Mater Sci Eng A 700:540–553Google Scholar
  26. 26.
    K. Alena, B. Vladimir, T. Sylvain, C. Cyrille, and U. Victor,2017 Influence of thermo-and HIP treatments on the microstructure and mechanical properties of IN625 alloy parts produced by selective laser melting: a comparative study, in Mater Sci Forum,Google Scholar
  27. 27.
    Witkin DB, Albright TV, Patel DN (2016) Empirical approach to understanding the fatigue behavior of metals made using additive manufacturing. Metall Mater Trans A 47:3823–3836Google Scholar
  28. 28.
    Bass L, Milner J, Gnäupel-Herold T, Moylan S (2018) Residual stress in additive manufactured nickel alloy 625 parts. J Manuf Sci Eng 140:061004Google Scholar
  29. 29.
    Slotwinski JA, Garboczi E, Stutzman PE, Ferraris CF, Watson SS, Peltz MA (2014) Characterization of metal powders used for additive manufacturing. J Res Natl Instit Standards Technol 119:460–494Google Scholar
  30. 30.
    Sutton AT, Kriewall CS, Leu MC, Newkirk JW (2017) Powder characterisation techniques and effects of powder characteristics on part properties in powder-bed fusion processes. Virtual and Physical Prototyping 12:3–29Google Scholar
  31. 31.
    Spierings AB, Schneider M, Eggenberger R (2011) Comparison of density measurement techniques for additive manufactured metallic parts. Rapid Prototyp J 17:380–386Google Scholar
  32. 32.
    “ASTM D7127-17,2017 Standard test method for measurement of surface roughness of abrasive blast cleaned metal surfaces using a portable stylus instrument,” ed: ASTM International, West Conshohocken, PA,Google Scholar
  33. 33.
    Schajer GS (2013) Practical residual stress measurement methods. John Wiley & SonsGoogle Scholar
  34. 34.
    Simson T, Emmel A, Dwars A, Böhm J (2017) Residual stress measurements on AISI 316L samples manufactured by selective laser melting. Addit Manuf 17:183–189Google Scholar
  35. 35.
    Aboulkhair NT, Everitt NM, Ashcroft I, Tuck C (2014) Reducing porosity in AlSi10Mg parts processed by selective laser melting. Addit Manuf 1:77–86Google Scholar
  36. 36.
    Yang T, Liu T, Liao W, MacDonald E, Wei H, Chen X, Jiang L (2019) The influence of process parameters on vertical surface roughness of the AlSi10Mg parts fabricated by selective laser melting. J Mater Process Technol 266:26–36Google Scholar
  37. 37.
    Maamoun A, Xue Y, Elbestawi M, Veldhuis S (2018) Effect of selective laser melting process parameters on the quality of Al alloy parts: powder characterization, density, surface roughness, and dimensional accuracy. Materials 11:2343Google Scholar
  38. 38.
    Gao F, Sonin AA (1994) Precise deposition of molten microdrops: the physics of digital microfabrication. Proc R Soc Lond A 444:533–554Google Scholar
  39. 39.
    McNallan M, Debroy T (1991) Effect of temperature and composition on surface tension in Fe-Ni-Cr alloys containing sulfur. Metall Trans B 22:557–560Google Scholar
  40. 40.
    Brooks R, Monaghan B, Barnicoat A, McCabe A, Mills K, Quested P (1996) The physical properties of alloys in the liquid and “mushy” states. Int J Thermophys 17:1151–1161Google Scholar
  41. 41.
    Calignano F, Manfredi D, Ambrosio E, Iuliano L, Fino P (2013) Influence of process parameters on surface roughness of aluminum parts produced by DMLS. Int J Adv Manuf Technol 67:2743–2751Google Scholar
  42. 42.
    Gunenthiram V, Peyre P, Schneider M, Dal M, Coste F, Fabbro R (2017) Analysis of laser–melt pool–powder bed interaction during the selective laser melting of a stainless steel. Journal of Laser Applications 29:022303Google Scholar
  43. 43.
    P. C. Sharma,1999 A textbook of production enginerring S. Chand Publishing,Google Scholar
  44. 44.
    Mercelis P, Kruth J-P (2006) Residual stresses in selective laser sintering and selective laser melting. Rapid Prototyp J 12:254–265Google Scholar
  45. 45.
    Kruth J-P, Deckers J, Yasa E, Wauthlé R (2012) Assessing and comparing influencing factors of residual stresses in selective laser melting using a novel analysis method. Proc Inst Mech Eng B J Eng Manuf 226:980–991Google Scholar
  46. 46.
    Liu Y, Yang Y, Wang D (2016) A study on the residual stress during selective laser melting (SLM) of metallic powder. Int J Adv Manuf Technol 87:647–656Google Scholar
  47. 47.
    Staub A, Spierings AB, Wegener K (2018) Correlation of meltpool characteristics and residual stresses at high laser intensity for metal lpbf process. Adv Mater Process Technol:1–9Google Scholar
  48. 48.
    Yadroitsev I, Yadroitsava I (2015) Evaluation of residual stress in stainless steel 316L and Ti6Al4V samples produced by selective laser melting. Virtual and Physical Prototyping 10:67–76Google Scholar
  49. 49.
    Parry L, Ashcroft I, Wildman R (2019) Geometrical effects on residual stress in selective laser melting. Addit Manuf 25:166–175Google Scholar
  50. 50.
    Yakout M, Elbestawi M, Veldhuis SC (2019) Density and mechanical properties in selective laser melting of invar 36 and stainless steel 316L. J Mater Process Technol 266:397–420Google Scholar
  51. 51.
    Withers PJ, Bhadeshia H (2001) Residual stress. Part 1–measurement techniques. Mater Sci Technol 17:355–365Google Scholar
  52. 52.
    Yakout M, Cadamuro A, Elbestawi M, Veldhuis SC (2017) The selection of process parameters in additive manufacturing for aerospace alloys. Int J Adv Manuf Technol 92:2081–2098Google Scholar
  53. 53.
    Prashanth K, Scudino S, Maity T, Das J, Eckert J (2017) Is the energy density a reliable parameter for materials synthesis by selective laser melting? Mater Res Lett 5:386–390Google Scholar

Copyright information

© Springer-Verlag London Ltd., part of Springer Nature 2019

Authors and Affiliations

  1. 1.Department of Mechanical EngineeringMcMaster UniversityHamiltonCanada
  2. 2.Additive Manufacturing Innovation CentreMohawk CollegeHamiltonCanada

Personalised recommendations