ISSN 1913-1844 E-ISSN 1913-1852 50Dilution Effect during Laser Cladd ing of Inconel 617 with Ni-Al [618308]

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ISSN 1913-1844 E-ISSN 1913-1852 50Dilution Effect during Laser Cladd ing of Inconel 617 with Ni-Al
Powders
Ahmed Ali Moosa
Department of Production Engineering and Metallurgy
University of Technology, Baghdad, Iraq
Tel: 964-790-179-3866 E-mail:[anonimizat]

Mohammed Jasim Kadhim
Department of Production Engineering and Metallurgy
University of Technology, Baghdad, Iraq
Tel: 964-790-549-9306 E-mail: [anonimizat]

Akeel Dhahir Subhi
Department of Production Engineering and Metallurgy
University of Technology, Baghdad, Iraq
Tel: 964-780-882-7048 E-mail: [anonimizat]
Abstract
In this study, continuous wave CO 2 laser with 1.7 and 2 kW were used to deposit clad layers of premixed
powders of either Ni-10 wt% Al or Ni-30 wt% Al onto inconel 617 substrate. Different cladding traverse speeds
in the range 1 to 35 mm/s were used for premixed clad powder of Ni-10 wt% Al and 1.65 to 11.2 mm/s for
premixed clad powder of Ni-30 wt% Al. Two powder feeding rates were used, 10 and 8.9 gm/min for premixed clad powders of Ni-10 wt% Al and Ni-30 wt% Al respectively. The other laser independent variables were selected to be constant. The results showed that different percentages of area dilution were found ranging from
3.7 to 78.3% for premixed clad powder of Ni-10 wt% Al and 6.9 to 41 % for premixed clad powder of Ni-30 wt% Al depending on the laser cladding independent variables used. Furthermore, dilution was affected mainly by
cladding traverse speeds.
Keywords:
Laser cladding, Dilution, Inconel 617, Ni-Al powders, Independent variables
1. Introduction
There has never been a period in history during which the evolution of materials and products has been faster
and the range of their properties more varied than today (Nenadov ć, 2002). The traditional forte of the materials
scientist has been the control of the physical, chemical and mechanical properties to produce an ensemble of
useful product profiles. With continually improving understanding of chemistry – structure – property relationships, incrementally improved materials steadily appear (Das and Davis, 1988). Lasers have greatly contributed to major fields of scien ce, technology and medicine since the first success in laser applications in
1960 (Maiman, 1960). Laser surface treatments under se lected variables have been proven to improve the
surface properties in several ferrous an d nonferrous alloys. Laser cladding is one of lase r surface treatments that
required overlay one metal or alloy w ith another, producing a sound interfacial bond with minimum dilution of
the cladding metal or alloy with substrate material (Yang, 1999; Manna, Majumdar, Chandra, Nayak and
Dahotre, 2006).
In industrial gas turbine engine manufacturing industry, materials used are specifically to meet the needs of the
hot gas path components exposed to the most severe op erating conditions; where high temperature creep, tensile
strength, ductility and oxidat ion resistance are required to withsta nd the loadings imposed. Replacement of the
degraded parts is a successful solution but costly. Theref ore, repairing the degraded parts for example turbine
blades tips is the most important process with accepted cost . Laser cladding with selected clad layers is the most
important repairing process distinguished with contro lled chemical composition and dimensions (Adak, Nash
and Chen, 2005). Several metals and alloys are used as a clad layer material. Nick el-Aluminum clad material
systems are distinguished with intermetallic compounds. Th e melted part of substrate that mixed with the clad
material makes clad layer studies very important (Liang and Su, 2000). Thus, one must study all properties that

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Published by Canadian Center of Science and Education 51are related to clad layer in order to approach the optimum evaluation. Therefore, careful evaluation of clad layers
may be used effectively to obtain a successful industrial applications after determination of the required clad
layer properties (Steen and Courtney, 1980).
In this work, light will be thrown to illuminate the mixing that occurred between clad layer and substrate
material, i.e.dilution percentage in order to control the chemical composition of clad layers of laser cladding of
inconel 617 with Ni-10 wt% Al and Ni-30 wt% Al premixed powder mixtures under different conditions.
2. Experimental Work
A 2 kW, fast axial continuous wave CO 2 laser (10.6 μm wavelength) was used to clad different powder mixtures
of chemical compositions of 90 wt% Ni (< 150 μm particle size) and 10 wt% Al (< 250 μm particle size) and the
other was 70 wt% Ni and 30 wt% Al on the inconel 617 substrate with dimensions of 75 x 40 x 5.5 mm. The main laser beam diameter was of approximately 22 mm which delivered to the substrate by focusing through 150 mm focal length KCl lens to obtain a 5 mm laser beam diameter on the substrate. Argon gas was blown to protect the lens from contamination. The chemical composition and microstructure of inconel 617 substrate were
illustrated in Table 1 and Fig.1 respectively.
The substrate samples were clamped with a suitable jig on a hydraulic powered x-y table which was moved
relative to the stationary laser beam. The cladding of samples was carried under argon gas as shrouding against
contamination from the atmosphere. The laser processing parameters are listed in Table 2. After laser cladding,
the features of clad layers such as depth of penetratio n and clad height were determined from the transverse
sections after grinding, polishing and etching. Area dilu tion as illustrated in Fig.2 can be obtained from the
following equation (Bruck, 1980):
%Area dilution = A
2/(A1 + A 2) x 1 0 0 1
where A 1 is the area of region (1)
A 2 is the area of region (2)
The areas of regions 1 and 2 present in Eq.1 can be calculated using an Image programme. In this programme,
standard ruler picture was used to establish measuremen t scale. After established scale of measurement, the
microstructure of clad layers of laser cladding of inconel 617 with Ni-10 wt% Al and Ni-30 wt% Al premixed clad powders of different cladding speeds was inserted to the programme separatly and measurement was taken
place. This can be accomplished by determin ation the region that must be measured.
3. Results and Discussion After the substrate has been wetted with the molten of pr emixed clad powder, spread ing of the melt pool on the
substrate will be took place. Spreading can be divided into distinct stages. The first stage is the very rapid spreading under the driving force for the balance of interf acial tensions characteristic of melt pool. In the second
stage, the substrate dissolve in the melt pool and forms compounds that nucleate on preferred sites at the solid-liquid interface and later grow to form the reactio n product (s). Laser clad layers properties are mainly
affected by dilution. Dilution determines the strengt h of clad layer. Generally, increasing area dilution
percentage for specific limit, the bond strength between the clad layer and substrate will be increased too.
Dilution is very important property especially in bond strength sensitive applications which are rquiring good wear resistance. In applications which are requiring goo d corrosion resistance or oxi dation resistance, the clad
layer composition must be approached that of clad mixture composition. Therefore, theoretically the best quality of clad layer is produced when the clad layer conser ve as possible its chemical composition with minimum
dilution. Figure. 3 shows the relations hip between dilution percentage (D) and cladding traverse speed (V) in
which the dilution increases at low and intermediate clad ding traverse speeds. At hi gh cladding traverse speed,
dilution is decreased as compared with intermediate cla dding traverse speed especially for premixed clad powder
of Ni-30 wt% Al. While for premixed clad powder of Ni-10 wt%Al, dilution continues in increasing rate at high cladding traverse speeds. This can be explained on the basis that at low cladding traverse speeds, melt penetration is high but because of the large thickness of clad layer, minimum melting in the substrate will take
place. This means that minimum mixing between premixed clad powder an d substrate material occurred. At
intermediate cladding traverse speeds, melt penetration is less than that in the low cladding traverse speed, but
because the clad height is small, th erefore, large melting in the substrate surface will occured. This means that
large mixing is taken place and therefore dilution is high. At high cladding traverse speeds, lower melt penetration will take place. The melt penetration, specia lly for premixed clad powder of Ni-30 wt% Al, does not
allow high mixing between clad layer and substrate materi al to occur, but when comp ared with mixing at low
cladding speeds, it will be high. In preplaced powder la ser cladding, the dilution was found to increase with

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ISSN 1913-1844 E-ISSN 1913-1852 52decreasing cladding traverse speed. This occurred when the laser beam melts the preplaced powder in order to
produce good bonding (Bruck, 1987).
The relationship between dilution percentage (D) and cladding rate (C r) (mm2/s) for premixed clad powders of
Ni-10 wt% Al and Ni-30 wt% Al is shown in Fig. 4. The relationship between dilution percentage and cladding
rate for premixed clad powder o Ni -10 wt% Al can be expressed as:
D = 2.72 C r0.9 2
While for premixed clad powder of Ni-30 wt% Al this relationship can be expressed as:
D = 0.015 C r1.07 3
The dilution percentage is increased w ith increasing cladding rate (increases in cladding traverse speed). This is
because with increasing cladding rate, any small heat input with respect to the clad height at a given cladding
rate is considered high; therefore, dilution is high. It is clear from Fig.6 that no decreasing in dilution percentage
took place at high cladding rate as compared with the relationship between dilution percentage and cladding speed for premixed clad powd er of Ni-30 wt% Al (Fig. 4). This is b ecause at high cladding traverse speed, the
magnitude of cladding rate decreases due to decrease in the clad width. As a result of dilution at higher cladding rate for premixed clad powder of Ni-30 wt% Al is low (19.7%) compared with previous dilution percentage
(41%); it approached in magnitude of the cladding rate at cladding traverse speed of 3.2 mm/s which is 23.1%.
Therefore, the decreasing in dilution percentage at high cladding rate does not appear on the graph (Fig. 4).
Conversely, the relationship between dilution percentage an d specific energy (Fig. 5) shows that the dilution is
increased exponentially with deceasing specific energy (increasing cladding speed). The relationship between
dilution percentage (D) and specific energy (E) (J/mm
2) for premixed clad powder of Ni-10% Al can be
expressed as:
D = 71.5 e – 0.009 E 4
While for premixed clad powder of Ni-30% Al this relationship can be expressed as: D = 0.41 e
– 0.0067 E 5
Increasing the dilution percentage with decreasing in sp ecific energy is related to increase in the cladding
traverse speed with decreasing in specific energy. Decr easing cladding traverse speed means that little mixing
will take place between premixed clad powder and substrate. Therefor e, dilution is low.
4. Conclusions
1) Laser cladding of inconel 617 substrate with Ni-10 wt% Al and Ni-30 wt% Al premixed clad powders is
feasible to obtain new hi gh quality surface layer.
2) Experiments on laser cladding indicate that single clad layers of Ni-10 wt% Al and Ni-30 wt% Al premixed
clad powders with dilution ranging from 3.7 to 78.3% and 6.9 to 41% respectively can be obtained.
3) The results showed that dilution is dependent mainly on cladding traverse speed with respect to constant of
other laser cladding process variables.
References Adak, B., Nash, P and Chen, D. (2005). Microstructura l characterization of lase r cladding of Cu-30Ni, J.
Materials Science, 40, 2051.
Bruck, G.J. (1987). High power laser beam cladding, J of Metals, 39, 10.
Das, S.K and Davis, L.A. (1988). High performance aerospace alloys vi a rapid solidification processing,
Materials Science Engineering, 98, 1.
Jendrzejewskia, R., Condeb, A., de Damboreneab, J and Sl iwinski, G. (2002). Charact erization of the laser-clad
stellite layers for protective coatings, Materials Design, 23, 83.
Liang, G.Y and Su, J.Y. (2000). The microstructure and tribological characteristics of laser-clad Ni–Cr–Al
coatings on aluminum alloy, Materials Science and Engineering A, 290, 207.
Maiman, T.H. (1960). Stimulated optical radiation in ruby, Nature, 187, 493.
Manna, I., Majumdar, J.D., Chandra, B.R., Nayak, S and Dahotre, N.B (2006). Laser surface cladding of
Fe–B–C, Fe–B–Si and Fe–BC–Si–Al–C on plain carbon steel, Surface Coating Technology, 201, 434.
Nenadovć, T.M (2002). Hyperfine surface structure, Materiali in Technologije, 36, 91.

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Published by Canadian Center of Science and Education 53Steen, W.M and Courtney, C.G.H. (1980). Hardfacing of nimonic 75 using 2 kW continuous wave CO 2 laser,
Metals Technology , June, 232.
Yang, Y. (1999). Microstructure and properties of laser-clad high-temperature wear-resistant alloys, Applied
Surface. Science, 140, 19.
Table 1. Chemical composition of inconel 617

Chemical composition, wt%
Ni Al Si Ti Co Mo Cr Fe
54.1 0.73 0.06 0.45 12.4 8.9 21.7 1.25

Table 2. Processing parameters studied
Power (p) 1.7-1.9 kW Beam diameter (d) 5 mm Traverse speed (V) 1-35 mm/s Interaction time (t) 0.14-5 s Power density (4P/ πd
2) (P A) 86-97 W/mm2
Specific energy (P/dV) 9.7-380 J/mm2
Powder feed rate (f) 8.9-10 g/min
Shrouding gas Argon

Figure 1. Microstructure of the inconel 617 substrate (marker is 15µm).

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ISSN 1913-1844 E-ISSN 1913-1852 54

Figure 2. Schematic shape of the laser clad layer.

Figure 3. The relationship between dilution percentage and cladding traverse speed of laser cladded inconel 617
with Ni-10 wt% Al and Ni-30 wt% Al premixed powders

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Published by Canadian Center of Science and Education 55
Figure 4. The relationship between dilution percentage a nd cladding rate of laser cladded inconel 617 with Ni-10
wt% Al and Ni-30 wt% Al premixed powders.

J/mm2
Figure 5. The relationship between dilution percentage and specific energy of laser
cladded inconel 617 with Ni-10 wt% Al and 30 wt% Al premixed powders. X Ni-10 wt% Al

Ni-30 wt% Al