Deposited gradient sample of two superalloys, Inconel 625 and Rene 80 using Directed Laser Deposition Performed Hot Mounting, Grinding, polishing to improve surface finish and Optical Microscopy for the verification of the grain structure Performed heat treatment at different temperatures improving the overall structure of the deposited samples Conducted hardness measurements for each gradient sample using Wilson Rockwell Tester.

1. Final Directed Study Report on Inconel 625-
Rene 80
Pratik Saxena
ABSTRACT
Directed Laser Deposition technology is a laser aided additive manufacturing method which
builds near net shaped components from CAD models into solid freeform fabrication by
combining rapid prototyping with laser cladding. In this study, gradient samples of Nickel-Based
superalloys Inconel 625 & Rene 80 was successfully fabricated using Directed Laser Deposition.
A molten pool was created by using high power CO2 laser of Inconel 625 & Rene 80 substrate in
which Inconel 625 & Rene 80 powders were injected in proper composition to create a 3D
gradient sample. Further, hot mounting of the deposited samples was created and to get better
surface finish grinding and polishing were done by using 300-1200 grit size paper and finally
polished with cloth. Then, Microhardness test was taken on 760 - 1200°C heat treated gradient
samples of Inconel 625 & Rene 80 to achieve best result from all the created samples. This study
demonstrate that new materials can be built by combining proper compositions of materials such
as Inconel 625 & Rene 80 by using Directed Laser Deposition.
INCONEL® 625
INCONEL® nickel-chromium-molybdenum compound 625 (UNS N06625/W. Nr. 2.4856) is utilized
for its high strength, phenomenal fabricability, and extraordinary corrosion resistance. Service
temperatures ranges from cryogenic to 1800°F (982°C).
Strength of INCONEL 625 is derived from the stiffness of molybdenum and niobium on its nickel-
chromium matrix; in this way precipitation hardening treatments are not required. This chemical
composition of elements is responsible higher resistanceto wide range of corrosive surroundings
of unusual severity as well as high temperature effects such as oxidation and carburization.
The properties of INCONEL compound 625 that settleon it an incredible decision for ocean water
applications are flexibility from local assault (pitting and crevice corrosion), high fatigue strength,
high tensile strength, and protection from chloride-ion stress-corrosion cracking. It is utilized as
wire rope for mooring links, propeller blades for gunboats, submarine
auxiliary propulsion motors, submarine quick disconnect fittings, deplete channels for Navy
utility water crafts, sheathing for undersea communication cables, submarine transducer
controls, and steam-line howls. Potential applications are springs, seals, howls for submerged
controls, electrical link connectors, flexure gadgets, and oceanographic instrument components
parts.

2. High tensile, creep, and rupture strength; remarkable fatigue and thermal fatigue strength;
oxidation resistance; and amazing weldability and braze ability are the properties of INCONEL
625 that make it intrigue to the aerospace field. It is being utilized as a part of such applications
as aircraft ducting system, thrust reverser system, engine exhaust system, resistance welded
honeycomb structures for housing motor controls, turbine shroud rings, fuel and water hydraulic
driven line tubing, splash bars, and heat exchanger tubing in environmental control frameworks.
It is additionally reasonable for combustion system transition liners, compressor vanes, turbine
seals, and thrust chamber tubing for rocket. The exceptional and flexible corrosion resistance of
INCONEL625 under an extensivevariety of temperatures and pressure is an essentialexplanation
behind its wide acknowledgment in the concoction handling field. Since of its simplicity of
creation, it is made into an assortment of segments for plant hardware. Its high strengths
empower it to be utilized, for instance, in thinner walled vessels or tubing than conceivable with
different materials, in this manner enhancing heat exchange and sparing weight. A few
applications requiring the combination of strength and corrosion resistance offered by INCONEL
625 are reaction vessels, bubble tops, refining sections, tubing, heat exchangers, valves and
transfer piping.
In the nuclear field, INCONEL 625 may be utilized for reactor-core and control-rod segments in
nuclear water reactors. The material can be chosen considering its high strength, incredible
uniform corrosion resistance, protection from stress breaking and incredible pitting resistance in
500°-600°F (260-316°C) water. Inconel 625 is likewise being considered in cutting edge reactor
concepts in view of its high admissible design quality at raised temperatures, particularly
between 1200°-1400°F (649-760°C).
Chemical Composition, %
Resistance toCorrosion:The high levelof chromium and molybdenum in Type 625 alloyprovides
a high level of pitting and crevice corrosion resistance to chloride contaminated media, such as
sea water, neutral salts and brines.

3. Physical properties,
Thermal Properties,

4. Electrical Resistivity,
Mechanical properties,
Applications,
 Aerospace
 Heat Exchangers
 Pressure Vessels
 Chemical Processing equipment’s handling mixed acids both reducing and oxidizing
 Bellows
 Expansion Joints
 Seawater Applications
 Aircraft Ducting System
 Jet Engine exhaust system
 Nuclear water reaction components
 Turbine shroud rings.

5. RENE 80
Rene 80 is a polycrystalline nickel-based super alloy commonly utilized to make first and second
stage turbine blades in present day jet engines. It has a fantastic combination of toughness,
thermal fatigue, high temperature strength, hot corrosion resistance, high rupture strength and
resistance to degradation in corrosive or oxidizing environments. Rene-80 has been utilized for
quite a while as an alloy for creation of the stream turbine blades.
These materials are broadly utilized as a part of rocket engines, aircraft, power-generation
turbines and nuclear power plant. Concentrated combination and process advancement
exercises amid the previous couple of decades have brought about RENE 80 that it can endure
normal temperatures of 1050°C with periodic excursions to temperatures as high as 1200°C.
Directional hardening of the alloy improves its mechanical properties as tensile strength is
increased by around 10– 15% and the creep life is reached out by 2– 4 times, when contrasted
with the traditionally cast material.
Chemical Composition, wt %
Co Cr Mo W Ti Al C B Zr Ni
9.5 14 4 4 5 3 .17 .015 .03 Bal
Physical properties,
Temper
ature
(°C)
Modulus
of
elasticit
y
(GPa)
Mean
coefficient of
thermal
expansion 10-
6/(°C) between
20(°C) and
Thermal
conducti
vity
(W/m·°C
)
Specific
thermal
capacit
y
(J/kg·°C
)
Specific
electrical
resistivity
(Ω
mm²/m)
Density
(kg/dm³)
Poisson’
s
coefficie
nt, ν
44 - - - - 0.34 - -
322 789 - 33.3 443 - - -
954 - 21 11.2 - - 414 311
Mechanical properties,
Tensile strength 919 (≥) Rm(MPa)
Yield Strength 845 (≥ Rp0.2(MPa)
Elongation 41 A (%)
ψ - ψ≥ (%)
Akv - Akv≥/J
HBS 235-268 -
HRC 30 -

6. Experimental procedure
The gradient sample of Inconel 625 & Rene 80 was deposited using Directed Energy Laser
Depositions process.The process fabricates metal parts directly from the Computer Aided Design
(CAD) solid models using a metal powder injected into a molten pool created by a focused, high-
powered laser beam.
A six-axis ABB robot is used. Both the materials in powder form are injected to the robot by
proper weight, composition and feed rate. Simultaneously, the substrate on which the deposition
is occurring is scanned under the beam/powder interaction zone to fabricate the desired cross-
sectional geometry. Consecutive layers are sequentially deposited, thereby producing a three-
dimensional metal component.
Gradient sample was created as shown above in manner that the 1st layer was made by 100% of
Inconel 625 & 0% Rene 80, 2nd layer was 90% Inconel 625 & 10% Rene 80, 3rd was 80% Inconel
625 & 20% Rene 80 continuing to 0% Inconel 625 & 100% Rene 80 in the last layer.
Inconel 625
100 %
0%
RENE 80
0 %
100%

7. HOT MOUNTING
After the deposition of the sample hot mounting is done. The clean and dry sample is put in a
mounting barrel in a hot mounting press, and the suitable mounting resin is added. A
temperature of around 180° C and a force of around 250 bars is applied and continued for 15-
20mins. After that it is cooled for another 15-20 mins using water and the cooling housing while
maintain the constant pressure.
Sample after the hot mounting is shown below. Further grinding and polishing is required to
clean the sample and remove scratches or in other deformation.

8. Grinding and Polishing
The main aim of grinding and polishing is to remove damaged or deformed surface material while
limiting the amount of additional surface damage in the shortest possible time.
Grinding uses fixed abrasive particles to remove damage or deformed material surface. In this
process we used four types of grit size papers which includes 300, 600, 1200 grit size paper and
after that polishing is done using cloth to obtain better surfacefinish. While grinding we maintain
90-degree angle after using each grit size paper to get better finish.
After grinding, polishing is done which uses free abrasives on a cloth, i.e. abrasive particles are
suspended in a lubricant that can slide or roll across the cloth and the sample providing mirror
like finish on the surface of the sample.

9. Heat Treatment
For heat treatment sample is carefully placed at center of the glass tube of the furnace, then
furnace is closed.Further, temperature and time cycleis manually adjusted. There are four stages
of heat treatment.
 1st at 1100°C for two hours for two samples.
 2nd at 1200°C for two hours for two samples.
 3rd at 760°C for sixteen hours for two samples. Both two samples are previously heat
treated, one of them is heat treated at 1100°C for 2hours and the other is heat treated at
1200°C for 2 hours.
 4th at 860°C for sixteen hours for two samples. Both two samples are previously heat
treated, one of them is heat treated at 1100°C for 2hours and the other is heat treated at
1200°C for 2 hours.
After the heat treatment of the sample is done, the red-hot sample is carefully removed from the
furnace and allowed to air cool at room temperature.

10. Hardness test
After grinding, polishing and heat treatment are completed hardness test is done on the sample.
For the hardness test we use MICRO MICKERS HARDNESS TESTER TUKON 2100 ™ at 500gm load,
20X magnification and dwell time of 10 seconds to test the hardness. To achieve best results, 4-
5 readings are taken in the center of every layer and average of all readings are calculated. After
the Hardness test, Origin software is used to plot the hardness graph of the samples.
Microhardness measurements of all deposited samples shows lots of variation at annealed
temperatures as the cooling rate of Directed Laser Deposition process is very high (103 K/s to 105
K/s). This high cooling rate increases the grain size and as per Hall-Petch relationship, hardness
decreases with the increase of grain size at room temperature and as Inconel 625 is a solution
strengthened superalloy, most of the strengthening elements i.e., Nb & Mo remain in the
austenite matrix, those are the main factors for the determination of hardness. Inconel 625
Forms γʺ (Ni3Nb) on performing solid solution treatment and ageing at annealed temperatures
of 1100-1200 °C for 2 hours, 760-860°C for 16 hours gives finer microstructure and alleviated
segregation of Nb & Mo which increases hardness.

11. Results of Hardness test of Inconel 625 & Rene 80 at different temperatures.
Secondly, Rene 80 is precipitation Harding material which forms γʹ (Ni3(Al,Ti) precipitate and
has higher hardness because of the bonding between (Ni3(Al,Ti) at As-deposited condition. In the
As-deposited condition the size γʹ phase decreases and the volume fraction of γʹ phase
increases which stops the growth of coarse γʹ particles and increases the growth of fine γʹ
particles which results in higher hardness. On the other hand, when Rene 80 is aged on higher
temperatures there is growth of coarse γʹ particles which increases ductility but decreases the
hardness as we can see from the graph above.

12. 1. AS-deposited Condition – From the graph we can see that Inconel 625 has hardness
around 234 HV and it is almost same till the composition of Rene 80 reaches 30%, But
when the composition of Rene 80 reaches 40% there is substantial increase in the
hardness of the sample, As Rene 80 has higher hardness and we can see the gradual
increasein hardness of the sample as the composition of Rene 80 is increasing and at 90%
composition of Rene 80 hardness of the sample is around 500 HV which almost double
when consider to the initial stage at 0% Rene 80.
2. At 1100°C - 760°C Heat Treatment – On heat treatment at 1100°C for 2 hours, 760°C for
sixteen hours Inconel 625 shows ageing behavior and γʺ (Ni3Nb) start to form which
increases the hardness of the sample. From the graph we can see that hardness of the
sample is gradually increasing as the composition of Rene 80 is increasing. At 30 %
composition of Rene 80 there is a sudden jump in the hardness which was around 390 HV
which was much higher when compared to As-deposited condition 235 HV. While
hardness decreased at 90%-100% Rene 80 due to the growth of coarse γʹ particles.
3. At 1100°C - 860°C Heat Treatment - On heat treatment at 1100°C for 2 hours, 860°C for
sixteen hours there are gradual increase in hardness as the composition of Rene 80 is
increased. Hardness of the sample decreased at 90-100% composition of Rene 80.
4. At 1200°C - 760°C Heat Treatment - On heat treatment at 1200°C for 2 hours, 760°C for
sixteen hours hardness is slightly higher when compared to 1100°C - 860°C Heat
Treatment condition till 30% Rene 80 composition in the sample then it decreased as the
composition of Rene 80 is increased due to the formation of coarse γʹ particles.
5. At 1200°C - 860°C Heat Treatment - On heat treatment at 1200°C for 2 hours, 860°C for
sixteen hours highest hardness was observed at 10%-20% and 60% - 80 % composition of
Rene 80 when compared to all the other heat treatment conditions due to the formation
of γʺ (Ni3Nb) phase in the sample because of higher temperature.
Initially for sample 0% composition of Rene 80 hardness was found to be almost similar for all
the cases.Forsamples 10% -20% Rene 80composition highesthardness was observed for 1200°C
- 860°C Heat Treatment condition, For samples 30% to 50% Rene 80 composition 1100°C - 760°C
Heat Treatment condition showed the highest hardness, For samples 60% to 80 % Rene 80
composition 1200°C - 860°C Heat Treatment condition showed the highest hardness and Finally
For samples 90% to 100% Rene 80 composition As-deposited case showed the higher hardness
due to the growth of fine γʹ particles.

13. Conclusion
Superalloy Inconel 625 and Rene 80 both are one of the best materials available in the market till
date with their unique microstructure, mechanical, physicaland chemical properties. Inconel 625
and Rene 80 are being used widely by different industries because of their ability to with stand
elevated temperatures, high strength, phenomenal fabricability and extraordinary corrosion
resistance. Depositing gradient sample of Inconel 625 and Rene 80 provides us 11 different
sample of different composition, mechanical and physical properties. Our aim is to obtain best
case scenario of the 11 new deposited samples which consist the properties of both Inconel 625
and Rene 80. The study demonstrate that new materials can be built by combining proper
compositions of materials such as Inconel 625 & Rene 80 by using Directed Laser Deposition.

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