Donald G Godfrey

Laser powder bed fusion can allow for faster and more efficient supply of aviation parts. Laser Powder Bed Fusion Machines must adhere to high standards of airworthiness held by the FAA and the EASA. Regulatory agencies have adopted a {performance-based regulation of additive components. Components created through additive manufacturing must meet or exceed the requirements of conventionally-created parts.

It can be an expensive and time-intensive process, costing upwards of hundreds of… Show more

Laser powder bed fusion can allow for faster and more efficient supply of aviation parts. Laser Powder Bed Fusion Machines must adhere to high standards of airworthiness held by the FAA and the EASA. Regulatory agencies have adopted a {performance-based regulation of additive components. Components created through additive manufacturing must meet or exceed the requirements of conventionally-created parts.

It can be an expensive and time-intensive process, costing upwards of hundreds of thousands of dollars and several years to complete. SLM Solutions is working to reduce this cost and shorten this schedule by providing game-changing solutions for standardization and qualification. When a company qualifies a component for air-worthiness they must qualify “the process” as well as “the machine” along with “the part”. This paper will walk you through the steps you need to meet the right standards for your machine.
This paper will focus on airworthiness and discuss the importance on airworthiness standards, Metallic Materials Properties Development Standardization, testing and qualification processes, and ensuring repeatability. Show less

In this study, the effect of post-process heat treatment on the microstructure and mechanical
properties of Hastelloy-X superalloy fabricated via two different additive manufacturing
technologies, namely, laser beam powder bed fusion (LB-PBF) and laser powder directed energy
deposition (LP-DED), is investigated. Microstructure was examined using scanning electron
microscopy (SEM) and electron backscattered diffraction (EBSD) analysis, while mechanical
properties were… Show more

In this study, the effect of post-process heat treatment on the microstructure and mechanical
properties of Hastelloy-X superalloy fabricated via two different additive manufacturing
technologies, namely, laser beam powder bed fusion (LB-PBF) and laser powder directed energy
deposition (LP-DED), is investigated. Microstructure was examined using scanning electron
microscopy (SEM) and electron backscattered diffraction (EBSD) analysis, while mechanical
properties were evaluated by macro-hardness testing using the Rockwell B method. Microstructure
of the alloys was studied thoroughly after several heat treatments that involve stress-relieving (at
1066°C for 1.5 hours), hot isostatic pressing (HIP at 1163°C for 3 hours under 103 MPa pressure),
and/or solution treatment (at 1177°C for 3 hours). The results revealed that, for both LB-PBF and
LP-DED Hastelloy-X, the post-process heat treatments resulted in uniform grain structure as well
as partial dissolution of carbides, although they have different grain sizes. Show less

Inconel 718 alloy fabricated by selective laser melting (SLM) (or laser powder-bed
fusion (LPBF)) has been post-process heat-treated by stress-relief anneal at 1065 ◦C; stress-relief
anneal (1065 ◦C) + solution treatment (at 720 ◦C) + aging (at 620 ◦C); hot isostatic pressing (HIP)
(at 1120–1200 ◦C); stress-relief anneal + HIP; and stress-relief anneal + HIP + solution treatment +
aging. Microstructure analysis utilizing optical metallography revealed primarily equiaxed… Show more

Inconel 718 alloy fabricated by selective laser melting (SLM) (or laser powder-bed
fusion (LPBF)) has been post-process heat-treated by stress-relief anneal at 1065 ◦C; stress-relief
anneal (1065 ◦C) + solution treatment (at 720 ◦C) + aging (at 620 ◦C); hot isostatic pressing (HIP)
(at 1120–1200 ◦C); stress-relief anneal + HIP; and stress-relief anneal + HIP + solution treatment +
aging. Microstructure analysis utilizing optical metallography revealed primarily equiaxed grain
structures (having average diameters ranging from ~30 to 49 microns) containing annealing twins,
and a high concentration of carbide precipitates in all HIP-related treatments in the grain boundaries
and intragrain regions. However, no precipitates nucleated on the {111} coherent annealing twin
boundaries because of their very low interfacial free energy in contrast to regular grain boundaries.
The mechanical properties for the as-fabricated Inconel 718 exhibited a yield stress of 0.64 GPa, UTS
of 0.98 GPa, and elongation of 26%. Following stress-relief anneal at 1065 ◦C, the yield stress dropped
to 0.60 GPa, while the elongation increased to 43%. The associated grain structure was an irregular,
somewhat elongated, recrystallized structure. This structure was preserved at a stress anneal at
1065 ◦C + solution treatment + aging, but grain boundary and intragrain precipitation resulted in a
doubling of the yield stress to 1.3 GPa and a reduced elongation of 12.6%. The results of HIP-related
post-process heat treatments involving temperatures above 1060 ◦C demonstrated that the yield stress
and elongations could be varied from 1.07 to 1.17 GPa and 11.4% to 19%, respectively. Corresponding
Rockwell C-scale hardness values also varied from 33 for the as-fabricated Inconel 718 to 53 for simple
post-process HIP treatment at 1163 ◦C. Show less

An essentially fully acicular alpha-prime martensite within an equiaxed grain structure was
produced in an Electron Beam Melting (EBM)-fabricated Ti-6Al-2Sn-4Zr-2Mo (Ti6242) alloy using two
different Arcam EBM machines: An A2X system employing tungsten filament thermionic electron
emission, and a Q20 system employing LaB6 thermionic electron emission. Post-process Hot Isostatic
Pressing (HIP) treatment for 2 h at 850, 950, and 1050 ◦C resulted in grain refinement and… Show more

An essentially fully acicular alpha-prime martensite within an equiaxed grain structure was
produced in an Electron Beam Melting (EBM)-fabricated Ti-6Al-2Sn-4Zr-2Mo (Ti6242) alloy using two
different Arcam EBM machines: An A2X system employing tungsten filament thermionic electron
emission, and a Q20 system employing LaB6 thermionic electron emission. Post-process Hot Isostatic
Pressing (HIP) treatment for 2 h at 850, 950, and 1050 ◦C resulted in grain refinement and equiaxed
grain growth along with alpha-prime martensite decomposition to form an intragranular mixture of
acicular martensite and alpha at 850 ◦C, and acicular alpha phase at 950 and 150 ◦C, often exhibiting
a Widmanstätten (basketweave) structure. The corresponding tensile yield stress and ultimate tensile
strength (UTS) associated with the grain growth and acicular alpha evolution decreased from ~1
and ~1.1 GPa, respectively, for the as-fabricated Ti6242 alloy to ~0.8 and 0.9 GPa, respectively, for HIP
at 1050 ◦C. The optimum elongation of ~15–16% occurred for HIP at 850 ◦C; for both EBM systems.
Because of the interactive role played by equiaxed grain growth and the intragrain, acicular alpha
microstructures, the hardness varied only by ~7% between 41 and 38 HRC. Show less

A wide range of post process hot isostatic pressing (HIP) studies of electron beam additively manufactured Ti-6Al-4V in this research program have shown that cooling rates of 103
◦C/min from temperatures above and below the beta transus produced acicular alpha-prime
martensite characteristic elongations < 10%. Optimum yield strength (0.9 GPa), UTS (1.0 GPa),
and elongation (∼14%) were achieved for slow cooling (at 102 ◦C/min) from 850 ◦C HIP which
produced a dense, Widmanstatten… Show more

A wide range of post process hot isostatic pressing (HIP) studies of electron beam additively manufactured Ti-6Al-4V in this research program have shown that cooling rates of 103
◦C/min from temperatures above and below the beta transus produced acicular alpha-prime
martensite characteristic elongations < 10%. Optimum yield strength (0.9 GPa), UTS (1.0 GPa),
and elongation (∼14%) were achieved for slow cooling (at 102 ◦C/min) from 850 ◦C HIP which
produced a dense, Widmanstatten alpha structure within the retained, as-fabricated columnar grains by alpha-prime decomposition. These results suggest that manipulation of AM
process parameters to produce a small-grain, equiaxed microstructure, HIPed below the beta
transus and slow cooled, will have a wide range of superior, isotropic mechanical properties
corresponding to a Widmanstatten alpha microstructure within the equiaxed grains. Show less

Mark Cola also presented

Presentation was given by Dr. Daira Legzdina. Dr. Robbie Adams also contributed to the presentation