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Progress in Additive Manufacturing (2022) 7:811–821

https://doi.org/10.1007/s40964-021-00221-2

FULL RESEARCH ARTICLE

Integrated weld preparation designs forthejoining ofL‑PBF

andconventional components viaTIG welding

OleGeisen1 · VinzenzMüller3· BenjaminGraf3· MichaelRethmeier2,3,4

Received: 22 April 2021 / Accepted: 13 September 2021 / Published online: 18 April 2022

Abstract

Laser powder bed fusion (L-PBF) of entire assemblies is not typically practical for technical and economic reasons. The build

size limitations and high production costs of L-PBF make it competitive for smaller, highly complex components, while the

less complex elements of an assembly are manufactured conventionally. This leads to scenarios that use L-PBF only where

it’s beneficial, and it require an integration and joining to form the final product. For example, L-PBF combustion swirlers

are welded onto cast parts to produce combustion systems for stationary gas turbines. Today, the welding process requires

complex welding fixtures and tack welds to ensure the correct alignment and positioning of the parts for repeatable weld

results. In this paper, L-PBF and milled weld preparations are presented as a way to simplify the Tungsten inert gas (TIG)

welding of rotationally symmetrical geometries using integrated features for alignment and fixation. Pipe specimens with the

proposed designs are manufactured in Inconel 625 using L-PBF and milling. The pipe assembly is tested and TIG welding is

performed for validation. 3D scans of the pipes before and after welding are evaluated, and the weld quality is examined via

metallography and computed tomography (CT) scans. All welds produced in this study passed the highest evaluation group

B according to DIN 5817. Thanks to good component alignment, safe handling, and a stable welding process, the developed

designs eliminate the need for part-specific fixtures, simplify the process chain, and increase the process reliability. The

results are applicable to a wide range of components with similar requirements.

Keywords L-PBF· Inconel 625· TIG welding· Dissimilar joints· Pipe weld preparation· Integrated alignment features·

AM feature integration

1 Introduction

Laser powder bed fusion (L-PBF) is one of the most mature

additive manufacturing (AM) technologies today, with

applications in the aerospace, medical and energy sectors,

among others [1]. One of the main advantages of L-PBF is

the design freedom that enables the manufacture of highly

complex geometries [2]. When these complex L-PBF-man-

ufactured components are integrated into a larger assembly

that requires substance-to-substance bonds, appropriate join-

ing methods and setups need to be determined.

The focus of this study lies on a combination scenario:

joining highly complex L-PBF-built swirlers to milled mani-

folds to form the combustion system of an SGT-8000H Sie-

mens Energy gas turbine, as shown in Fig.1. The material

used for both the swirlers and the manifold in serial produc-

tion is Inconel 625 (IN625); Tungsten inert gas (TIG) weld-

ing is used as the joining technology.

The geometric accuracy of the weld assembly is critical

to the performance of the combustion system. The position-

ing of the swirlers entails a centering, a rotational align-

ment, and an axial distancing, as illustrated in Table1. For

prototypes or components with low production volumes,

this is commonly achieved with manual alignment. In

* Ole Geisen

Ole.Geisen@siemens-energy.com

Vinzenz Müller

V[email protected]er.de

Michael Rethmeier

Michael.R[email protected]

1 Siemens Energy Global GmbH & Co. KG, Berlin, Germany

2 Technical University ofBerlin, Berlin, Germany

3 Fraunhofer Institute forProduction Systems andDesign

Technology IPK, Berlin, Germany

4 Federal Institute forMaterials Research andTesting, Berlin,

Germany

812 Progress in Additive Manufacturing (2022) 7:811–821

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serial production, part-specific fixtures are often used for

improved productivity and reproducibility. After the posi-

tioning, standard welding process chains usually include

tack welding operations, which are necessary for prelimi-

nary fixation of the components before the actual weld

seams are set.

The goal of this study was to tap the potentials of

L-PBF to eliminate the need for fixtures and to simplify

the welding-related process chain by developing and test-

ing novel weld preparation designs to fulfilling the fol-

lowing tasks:

1. Part positioning

a. Centering

b. Rotation

c. Axial distance

2. Part fixation

2 The State oftheart

Research on the welding of materials produced with L-PBF

is covered in numerous studies, for example by Wits etal.

[3], Casalino etal. [4] and Mäkikangas etal. [5]. The joining

of machined and as-built L-PBF tubes from Ni-based super-

alloys IN625 and IN718 via laser beam was investigated

by Jokisch etal. [6]. While the weldability was generally

shown, some as-built L-PBF weld edges included agglom-

erations of silicate-like inclusions. In contrast, machined

weld edges had a shiny surface with no inclusions, indi-

cating an influence of the L-PBF surface on the welding.

Geisen etal. [7] successfully joined L-PBF manufactured

tubes from IN625 and IN718 via TIG welding. All speci-

mens were machined to a V-seam weld preparation, and no

as-built edges were welded. Unlike Jokisch etal., the authors

did not discover significant defects.

One of the key advantages of AM is the ability to inte-

grate additional functions and features into the design with-

out increasing the manufacturing costs. This feature can be

used to improve assembly setups. For example, Klahn etal.

[8] and Ramírez [9] investigated the integration of snap-

fit joints to simplify the assembly of polymeric AM com-

ponents. The standard ISO/ASTM 52910 [10] also states

that AM can yield great potential when assembly features

are included in AM components. ISO/ASTM 52911–2 [11]

names specific AM geometries such as hooks and threads to

connect components.

The motivation for the research of Fieger etal. [12] into

joining L-PBF and conventionally manufactured steel parts

was the restricted build volume of L-PBF machines and

the higher efficiency for the manufacturing of small and

medium-sized parts compared with large parts. While the

design advantages of AM components can offer benefits

for part assembly, little research has been done in the field

of welding-related AM designs. Schwarz etal. [13] stud-

ied the welding of wrought and L-PBF stainless steel 316L

with TIG and laser beam welding. To improve the welding

process, they developed L-PBF weld joint geometries for

thin-walled metal sheets. The geometries include an inte-

grated weld joint backing and geometrical features for the

positioning of specimens. While this improved the welding

process, clamping and tack welding of the specimens was

still required. In addition, the geometries weren’t developed

or tested for circumferential weld seams.

Fig. 1 SGT-8000(H) combustion system with weld seams between

swirlers and manifolds highlighted in red

Table 1 Swirler positioning

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The following investigation will address this research gap.

Based on the swirler use case, the focus will be on circum-

ferential weld joints of IN625 parts and TIG welding. The

targeted designs need to cover the above-mentioned main

tasks (centering, rotation, axial distancing, and part fixation)

while respecting both L-PBF and milling constraints. The

part assembly before welding will be analyzed, followed by

a validation of the seam quality and the geometric accuracy.

Finally, the applicability of the results to other use cases and

industries will be discussed.

3 Materials andmethods

The base material for both the L-PBF and the conventional

specimens was Inconel 625 (IN625), a high temperature-

resistant Nickel-base superalloy commonly used in gas tur-

bine combustion systems. Thermanit 625 (UTP A 6222 Mo)

was used as filler material. It’s designed for weld joints of

similar high-strength and highly corrosion-resistant Nickel-

based alloys [14, 15]. The compositions are listed in Table2.

The L-PBF specimens were produced with IN625 pow-

der from EOS GmbH on an EOS M290 using standard pro-

cess parameters with a layer thickness of 40µm from EOS

GmbH. All L-PBF specimens were solution annealed and

grid blasted with silicon carbide. The milling was performed

on a five-axis CNC milling center (Alzmetall GS800) using

Siemens NX CAM software for programming. The milled

specimens were machined from sections of semi-finished

IN625 pipes with a diameter of 48.3mm and a wall thick-

ness of 3.68mm, providing about 0.3 of machining stock.

The final specimen geometries are shown in Fig.2. The

L-PBF and milled pipe specimens had a length of 75mm,

a diameter of 48mm, and a wall thickness of 3.4mm. Ori-

entation features (OF) were added on the outer diameter of

the pipe specimens to provide planes for referencing the 3D

scanned parts.

Optical blue light scans (3D scans) were performed with

an ATOS 5 optical metrology system (GOM GmbH). The

software GOM Inspect Professional was used to analyze and

evaluate the scan data.

TIG welding was performed on a Polysoude CNC weld-

ing lathe (see Fig.3b). The assembled probe was clamped

on the milled specimen, with continuous gas feeding on the

inside.

Argon (grade 4.6) with a flow rate of 10l/min was used

for purging and forming. The parameters of the root and

cover layer (shown in Fig.4b) are listed in Table3. The

specimens were assembled manually without tack welds.

No fixtures were used for alignment and fixation prior to

and during welding.

The metallographic cuts of the weld seams were produced

with a final polish using 3µm diamond paste to expose the

microstructure and detect pores and cracks. The cuts were

Table 2 Chemical compositions of Inconel 625 (powder and milled tube) and of the filler material Thermanit 625 in weight-percent (wt.%)

Ni Cr Fe Mo Nb + Ta C Mn, Si Si P, S Co Al, Ti

Inconel 625 Bal 20.0–23.0 ≤ 5.0 8.0–10.0 3.15–4.15 ≤ 0.1 ≤ 0.5 ≤ 0.5 ≤ 0.015 ≤ 1.0 ≤ 0.4

Thermanit 625 Bal 22 < 0.5 9 3.6 0.03 0.2 0.25 – – –

Fig. 2 Specimen geometry a side view, b front view of an assembled pair of welding pipes with positions of orientation features (OF) used in all

designs

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electrochemically etched with Kalling's II etchant. Light

optical microscopy (LOM) was conducted using a Zeiss

Axio Imager A2m microscope. An electron backscatter

diffraction (EBSD) analysis was conducted using a Zeiss

Sigma REM System equipped with a Bruker X-Flash EBSD

detector.

4 Weld preparation designs

In this study, two different weld preparation designs were

developed. The designs are based on the standard joint

geometry depicted in Fig.4a. The butt joint of standard

setup allows to define an axial distance to be defined, but

centering, rotation and fixation are not covered. Both designs

developed in this study have an additional circumferential

wall for centering, as shown in Fig.6.

The features for limiting the radial and axial movement

after assembly need to fit into the design space and meet the

manufacturing requirements: Standard L-PBF design rules

on overhangs (45°) and minimum wall thickness (0.3mm)

apply, while the milling is performed using standard tools

with a minimum groove width of 0.2mm, as illustrated in

Fig.5.

Fig. 3 Polysoude orbital TIG

welding station with(a view of

the welding lathe and b detailed

view of the torch with the

Tungsten electrode (left) and

Thermanit 625 wire (right)

Fig. 4 a Standard weld preparation geometry, b root and cover pass

Table 3 Welding parameters for root and cover layer

Parameter Root pass Cover pass

Current type Direct current Direct current

Voltage 8.8V 9.0V

Peak current 94 A 64 A

Base current 47 A 24 A

Peak current interval 170ms 170ms

Base current interval 70ms 70ms

Rotation speed 70mm/min 85mm/min

Wire feed 600mm/min 250mm/min

Fig. 5 Geometric constraints for a L-PBF with a layer thickness of

40µm, allowable overhang of 45°, min. wall thickness of 0.3mm; b

milling tool with a groove width of 0.2mm, chamfer of 45°, max.

depth of 1.5mm; dimensions not to scale; expected L-PBF roughness

in dashed red, ideal milling contour in dotted blue

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4.1 Snap‑fit design

The snap-fit design includes complementary tongue-groove

geometries for the rotational alignment: A cut-out in the wall

on the milled side (“groove”) is complemented by a protru-

sion (“tongue”) on the L-PBF geometry. Figure6b shows

details of the L-PBF and the milling design in CAD. The

axial fixation uses snap-fit pins that are integrated in the

L-PBF weld preparation. Gaps between the pins and the cir-

cumferential walls allow the pins to deflect during assembly.

The pins and the milled slots create an interlocking fixation.

4.2 Bayonet design

The bayonet design includes bayonet mount features for part

fixation, as illustrated in Fig.7. After plugging both sides

together, the parts must be twisted to interlock the bayonet

geometries. Integrated end-stop surfaces stop the rotation at

a defined angle to ensure the correct rotational alignment.

The L-PBF downskin surface and the corresponding milled

surface have an overhang angle of 45° to enable support-free

manufacturing via L-PBF. A standard milling tool as shown

in Fig.5b is used to create the V-shaped bayonet feature.

5 Results anddiscussion

5.1 L‑PBF results

Close-ups of the L-PBF specimens with the correspond-

ing CAD models are shown in Fig.8. The parts were built

with no interruptions and the alignment features show the

expected resolution. No difference in L-PBF production

cost and lead time was observed, because the total number

of layers remained unchanged with only minor changes in

total part volume. The L-PBF specimens were not machined.

As is common with L-PBF components, the downskin sur-

faces showed a higher surface roughness (compare [16]).

While this can increase friction and require additional effort

during assembly, the same effect can improve the fixation

by preventing the parts from untwisting and unintentional

disassembly.

Irregularities were found on several thin-walled snap-

fit pins. They showed bulky material accumulation and

deformed pin walls. All affected pins were positioned in

parallel to the steel recoater blade during the build job,

and the material accumulations were only observed in the

recoating direction, as shown in Fig.9. All other pins which

were not positioned in parallel to the recoater were manu-

factured without errors. It is, therefore likely that the defects

Fig. 6 Snap-fit design with a L-PBF geometry with tongue and pin, b milling geometry with groove and shoulder, c schematic assembly design

Fig. 7 Bayonet design with a L-PBF geometry (male), b milling geometry (female), c schematic assembly design

816 Progress in Additive Manufacturing (2022) 7:811–821

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were caused by contact with the recoater blade, with the

wall thickness of 0.35mm proving too low to withstand the

forces occurring during the recoating process. The fixation

function of the damaged pins is likely to be limited, and the

affected parts are, therefore, discarded.

The metallographic cuts of the unwelded specimens in

Fig.13a, c show cross-sections of the fixation features for

axial fixation. Some individual pores were detected in the

L-PBF specimens, especially in the near-surface area, which

is common for L-PBF [17]. All the pores were within the

acceptance levels of the swirler and no defects, like cracks

or lack of fusion were observed.

5.2 Milling results

Figure10 shows close-up views of the milled weld joint

preparations. No significant errors or irregularities were

observed. The increased complexity of the developed

designs compared with the state-of-the-art geometry resulted

in increase in milling lead time for the weld preparation of

about 30 percent for both designs. The milled geometries

could be produced with commercially available, non-cus-

tomized milling tools, making the designs also suitable for

small serial production.

5.3 Fixation capability

For the assembly, specimens of the bayonet mount had to

be plugged together and then twisted subsequently. During

the first assembly operation, high resistance to the twisting

was observed. The bending of the bayonet geometry (see

Fig.13c) was likely caused in the first assembly due to a

tight part fit of the joint. With repeating assemblies, a con-

stant fit was obtained. After assembly, it was not possible

to separate the specimens under manually applied axial or

radial loads that imitated rough shop floor handling.

The snap-fit design is assembled by pushing the speci-

mens together axially. This assembly required significantly

less force than the bayonet design. It was possible to manu-

ally disconnect specimens by applying an axial force. The

Fig. 8 Close-up images of

L-PBF specimens with a

snap-fit features and b bayonet

features

Fig. 9 Deformed snap-fit pins a on the outer diameter, b on the inner

diameter, with recoating direction

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snap-fit pins appeared to deform plastically with every

assembly iteration: After more than five assemblies, the

interlocking became too weak to hold the specimen’s dead

weight. Reliable handling and subsequent repeatable weld-

ing results can, therefore, can’t be guaranteed when the parts

are disassembled multiple times.

Overall, the bayonet design creates a stronger fixation.

The handling of assembled components is considered safer

with the bayonet. The bayonet could be suitable for heavier

components and therefore for a wider range of potential use

cases. The assembly and handling appeared to be stable and

repeatable, potentially reducing non-conformance costs and

improving cycle times in production.

5.4 Geometrical alignment beforewelding

Four pairs of assembled specimens of each design were

3D scanned in horizontal position before welding. Gravity

would therefore expose any allowance or gap between the

assembled specimens, resulting in a mismatch of the center

lines (as can be seen in Fig.11c. The orientation features on

the specimens were used for reference.

The axial distance of the orientation features was

48.14mm on average (48mm target distance). The short-

est distance was 47.97mm, the maximum distance was

48.33mm. The results indicate a good geometrical accuracy

of the joints with deviations within the acceptable limits for

the swirler use case (± 0.6mm).

The average angular deviation was measured to analyze

the rotational alignment of the specimens. On average, the

deviation was 0.37°. Negative values for the bayonet design

indicate that the specimens were not twisted far enough.

The highest absolute deviation of −1.14° was measured

on a bayonet specimen. Its assembly showed resistance to

Fig. 10 Close-up images of

milled specimens with a snap-fit

features and b bayonet features

Fig. 11 3D scan results before welding of a snap-fit and b bayonet

design with measured center lines of the L-PBF cylinders in rela-

tion to the target center lines. A scaling factor of 30 was applied to

improve visibility

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twisting due to a tight part fit, which was likely the cause of

the angular deviation.

The centering of the cylinders was analyzed by measur-

ing the position deviation of the L-PBF center lines relative

to the center line of the milled specimen. Selected 3D scan

results are depicted in Fig.11. The center lines of the bayo-

net design are almost parallel to the target, with low absolute

deviations as shown in Fig.11b. The 3D scans of the snap-fit

design showed a sagging of the L-PBF cylinder in the direc-

tion of gravity, resulting in a sloping L-PBF center line (see

Fig.11a). The cylinder sagging confirms the results of the

assembly tests, where a weaker fixation of the snap-fit com-

pared with the bayonet was observed. The average centering

deviation of all the snap-fit specimens was 0.70mm, and the

average deviation of the bayonet specimens was 0.28mm.

Only the bayonet design therefore enables an assembly that

meets the positioning accuracy required for the component

after welding (compare Table1).

5.5 Geometrical alignment afterwelding

Weld shrinkage led to a reduced axial distance and over-

all length of the specimens. This resulted in an average

orientation feature distance of 47.30mm after welding.

The shrinkage was relatively constant, with a variation

of approximately ± 0.20mm over all the samples, and it

can, therefore, be easily be compensated by systematically

increasing the part length. A higher shrinkage of the L-PBF

parts, as reported by Schwarz etal. [13], was not observed.

The welding had no negative impact on the angular align-

ment, with comparable results before and after welding.

However, an impact on the center line mismatch was

observed, as shown in two examples in Fig.12. Both cases

show a slight torsion of the cylinders, with a maximum

radial center line deviation of 0.5mm for the snap-fit and

0.4mm for the bayonet design. While at 0.7mm the average

deviation of the snap-fit specimens is similar to the results

before welding, the average deviation of the bayonet design

increases by a factor of 2.4. The deformation direction rela-

tive to the starting point of the circumferential weld showed

a uniform trend over all designs, as seen in the examples

in Fig.12. The mechanical fixation of all parts remained

intact during welding and led to acceptable welding results:

while most of the welded parts met the centering require-

ment of 0.5mm defined for the swirlers, the deviations were

all within the process window of heat straightening. The

maximum deviation observed was 1.03mm. As a welding

correction process, heat straightening is a standard step in

the production of combustion systems today when using

fixture. However, researchers should determine whether the

precise alignment of the bayonet design after assembly can

be preserved by adding tack welds before the circumferential

welding. To summarize, the proposed fixture-less designs

perform as well as or better than the current design with

fixtures, while enabling significant time savings during weld

preparation, because of part alignment and tack-welding

and are not required. Eliminating the dependency on part-

specific fixtures is an additional advantage that can increase

production flexibility.

5.6 Weld joint analysis

The weld seams were analyzed using evaluation criteria

from DIN EN ISO 5817 [18]. The goal was to achieve qual-

ity level B for all welds, which is the required classification

for most weld seams in gas turbine manufacturing.

In the visual inspections, no weld seam showed exter-

nal defects like macro cracks or open pores on the surfaces.

Fig. 12 3D scan results after welding of a snap-fit design and b bayo-

net design with measured center lines of the L-PBF cylinders in rela-

tion to the target center lines. A scaling factor of 30 for the shown

deviations was used to improve visibility. 0° indicates the start posi-

tion of the root weld

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Uniform and circularly textured weld beads were formed on

the cover layer. Even though the weld preparations were not

machined and pores were observed under the L-PBF sur-

face, no inclusions or other defects on the weld surface were

present, as were found in the study of Jokisch etal. [6]. The

quality of the welds is comparable to the results of Geisen

etal. for simple machined weld preparations [7].

A comprehensive volume inspection was conducted

by TÜV Rheinland GmbH with CT scans of all welded

specimens. Cracks, cavities, dimensions lack of fusion, and

penetration were examined and the findings were classi-

fied according to DIN EN ISO 6520–1. All results met the

acceptance criteria.

Metallographic cuts were produced by cutting the speci-

mens at the positions of the integrated features (the pins

or bayonet mounts). The highest risk of internal defects

was expected to be found here due to increased surface

roughness and gaps or void regions between the features.

Insufficient purging with forming gas, exacerbated by the

rough L-PBF surfaces, could have led to a weld contami-

nation with entrapped oxygen and increased pore develop-

ment. In Fig.13, one metallographic cut is presented for

each design, both non-welded (left) and welded (right). The

metallographic cuts do not show any cracks, cavities or lack

of fusion or lack of penetration. All internal features were

completely dissolved in the melt pool. While occasionally

small single pores with a diameter < 50µm were present, no

larger pores or clustered porosity were detected. In the cuts,

a visual distinction can be made between the root and top

layer of the weld seam. The top layer excess was between

0.6 and 0.8mm, and the root excess was between 0.5mm

and 1.1mm for all measurements, fulfilling the criteria per

DIN EN ISO 5817 for quality level B. The cross section

of the welded bayonet mount in Fig.13d shows a shifted

cover layer, likely caused by a misalignment of the electrode.

For serial production, the electrode alignment needs to be

improved to ensure repeatable results.

Additional images of the heat affected zone (HAZ) of the

snap-fit design are shown in Fig.14. The toes of the weld

show sufficient overlap and a smooth transition to the base

material. The change in microstructure of the HAZ is more

apparent in the fine-grained wrought material in Fig.14b,

with a significant increase in grain size.

Figure15 shows an EBSD image cut from the bayonet

design. The grain sizes in the weld material are significantly

larger compared to both the L-PBF and the conventional

base material on the left and right side, respectively. An epi-

taxial grain growth can be observed at the fusion lines both

between the base material and the root layer and between the

root and the cover layer. These findings are in line with the

results from Geisen etal. [7], where increased grain sizes

and epitaxial grain growth were also observed. The heat

affected zone of the L-PBF material on the left side shows

a less homogeneous grain size distribution compared to the

Fig. 13 Metallographic cuts of the snap-fit joint in a assembled, b welded condition, and of the bayonet joint in c assembled, d welded condi-

tion; including root penetration and cover excess measurements

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conventional base material on the right side. As stated by

Nguejio etal. [19] and Li etal. [20], this is a well-known

difference between L-PBF and wrought material.

In summary, no difference in weld joint quality could be

detected between the two designs. All weld seams were free

of significant external or internal defects. All integrated fea-

tures were completely dissolved in the weld, and the root

and cover excess dimensions were within tolerances. The

weld quality per DIN EN ISO 5817 can be categorized in

quality level B for all weld seams. This indicates that the

welding parameters applied were suitable for the designs. It

also proves adequate dimensioning of the integrated features,

and a balance between assembly functions and weldability.

6 Conclusion

The following conclusions can be drawn:

• Combining milling and L-PBF constraints in the weld

preparation design is possible when using standard set-

tings for both technologies

• Multiple assembly mechanisms and design principles can

be employed

• Assembly of printed and milled parts meets requirements

o Positioning is within tolerances

o Fixation is safe for industrial environments and han-

dling during production

• Welding of the investigated designs meets quality

requirements

o Quality level B, DIN 5187

o Geometrical accuracy is comparable to state-of-the-

art weld preparation (subsequent heat straightening

necessary)

• Fixture-free production with no tack welds is possible,

with the bayonet design showing the most robust results

and the best potential for serial production, while the

snap-fit design offers more design freedom and is appli-

cable to non-symmetric parts

• Manufacturing costs can be reduced with improved lead

time, lower non-conformance costs, and elimination of

fixture costs

Fig. 14 Details of the heat affected zone of snap-fit joint, a L-PBF material, b wrought material

Fig. 15 EBSD image of a weld seam with bayonet mount; L-PBF

specimen on the left, milled specimen on the right

821Progress in Additive Manufacturing (2022) 7:811–821

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7 Summary

The successful integration of positioning and fixation into

the part design, as demonstrated in this study, offers the

opportunity to improve costs, lead time and quality in the

serial production of L-PBF parts in mixed joining setups.

The solutions developed are applicable to all combustion

systems in Siemens Energy gas turbines, because these com-

ponents all have similar requirements and materials. In other

industries, like oil and gas, similar use cases with different

materials and dimensions can be anticipated.

For future studies, we recommend that investigations

be conducted on the mechanical properties of TIG welded

specimens joining L-PBF to cast or wrought material. The

designs should be investigated for their suitability for join-

ing L-PBF to L-PBF components, and the impact of sur-

face roughness on both parts should be studied. In addition,

different materials and part dimensions can be analyzed.

Finally, the transferability of the results to nonrotationally

symmetric components can be studied to cover an even

wider range of use cases.

Funding Open Access funding enabled and organized by Projekt

DEAL.

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