mechanical, structural and tribological characterisation of high nickel content alloys before and...

Mechanical, Structural and Tribological Characterisation of High Nickel Content Alloys before and after

Arc Activated Plasma Nitriding

Mechanical, Structural and Tribological Characterisation of High Nickel Content Alloys before and after Arc Activated Plasma Nitriding

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Mechanical, Structural and Tribological

Characterisation of High Nickel Content Alloys

before and after Arc Activated Plasma Nitriding

J. Fernández, E. Almandoz, J. Arrikaberri, S. Kulkarni, J. F. Palacio,G.G. Fuentes, J.A. García, R. Rodríguez

AIN – Asociación de la Industria Navarra, SpainAIN – Asociación de la Industria Navarra, Spain

IVC-19 / ICN+T 2013 and partner conferences

9th – 13th September 2013, Paris (France)

Outline

1. Introduction

2. Objectives

3. Methodology

4. Characterization: Results and discussion




5. Summary

6. Future work

7. Acknowledgments

Outline

1.Introduction

2. Objectives

3. Methodology




5. Summary

6. Future work

7. Acknowledgments

The alloys under study

C (%) Ni (%) Co (%) Mo (%) Ti (%) Al (%) Fe (%)

Specified < 0.03 17-19 8.5-9.5 4.7-5.2 0.6-0.7 < 0.15 Balance

Measured 0.008 17.31 9.05 5.10 0.66 0.11 Balance

1) Maraging Grade 300, which belongs to the group of maraging steels with18% Ni and Co containing.



Chemical composition of Maraging Grade 300

30.3 ± 0.2 HRc after quenching at 820 ºC during 1 h

52.1 ± 0.2 HRc after aging at 485 ºC during 3h

Dimensions: Ø = 35 mm; thickness = 5 mm

Grinded and polished to Ra ~ 10 nm

Samples


C (%) Cr (%) Fe (%) Mn (%) Si (%) Cu (%) S (%) Ni (%)

Specified < 0.15 14-17 6-10 ≤ 1 ≤ 0.50 ≤ 0.50 ≤ 0.015 Balance

Measured 0.12 16.3 9.1 0.54 0.43 0.32 0.011 Balance

Chemical composition of INCONEL alloy 600

2) INCONEL alloy 600, which belongs to the group of nickel superalloys.




17.0 ± 0.2 HRc



Samples


C (%) Cr (%) Fe (%) Mo (%) Ti (%) Al (%) Si (%) B (%)

Specified ≤ 0.0080 17-21 17 2.8-3.3 0.65-1.15 0.20-0.80 ≤ 0.35 ≤0.0060

Measured 0.006 17.6 17.1 2.9 0.96 0.55 0.30 0.002

Co (%) Cu (%) Mn (%) Nb (%) P (%) S (%) Ni (%)

Specified ≤ 1.0 ≤ 0.30 ≤ 0.35 4.75-5.5 ≤ 0.015 ≤ 0.015 Balance

3) INCONEL alloy 718, which belongs to the group of nickel superalloys.



Specified ≤ 1.0 ≤ 0.30 ≤ 0.35 4.75-5.5 ≤ 0.015 ≤ 0.015 Balance

Measured 0.75 0.22 0.26 5.1 0.009 0.012 Balance


41.8 ± 0.8 HRc



Samples

Outline

1. Introduction

2.Objectives

3. Methodology




5. Summary

6. Future work

7. Acknowledgments

Objectives

Study the mechanical, structural and tribological

properties of high nickel content alloys before and

after an arc activated plasma nitriding process.

What for?



� Increasing the superficial hardness

� Increasing the wear resistance (room &high temperature)

What for?

Outline

1. Introduction

2. Objectives

3.Methodology




5. Summary

6. Future work

7. Acknowledgments

� 1: Reactor

� 2: Samples

� 3: Electric arc discharge units

� 4: Heat source

� 5: Sample holder

� 6: Electron collector (anode)

- 6.1: Electric field concentrator

Arc activated plasma nitriding



- 6.1: Electric field concentrator spirals

� 7: Gas inlet

� 8: Vacuum system

� 9: Pulsed DC current source

� 10: DC current source

� 11: DC power system

Spanish patent: ES 2 344 981 B1 in 2011and European patent EP 2 369 028 B1 in2013.


Ionizedgas

N + Ar (+H )

e-

e-

+� Vacuum: 5x10-3 Pa

� Pre-heating: 350 ºC

� Cleaning: Ar

Steps



N2 + Ar (+H2)e-

e-

PVD scheme

+

+

� Cleaning: Ar

� Nitriding: 1 Pa, 425 ºC, 60 min

90 sccm N2 & Ar

� Cooling down


Characteristics Benefits

� High ionization rate

� Low pressure

� High ratio of active specimens

� Versatility for future treatments(DUPLEX treatments: nitriding + PVD,nitriding + oxidation)

� No formation of white layer



� No formation of white layer

Labelling

Material Untreated Nitrided

Maraging 300 MAR-3 MAR-3N

INCONEL 600 INC-6 INC-6N

INCONEL 718 INC-7 INC-7NMETAPLAS PVD MZR 323 equipment

Outline

1. Introduction

2. Objectives

3. Methodology





5. Summary

6. Future work

7. Acknowledgments

Chemical analysis: GD-OES

MAR-3N

INC-6N INC-7N0 3 6 9 12 15 18

0

10

20

30

40

50

60

70

Ato

mic

%

C Fe Mo N O Ti Co Ni



0 3 6 9 12 15 18

Depth (microns)

0 1 2 3 4 50

10

20

30

40

50

60

70

Ato

mic

%

Depth (microns)

C Cr Fe N O Si Ni Cu Mn

0 1 2 3 4 50

10

20

30

40

50

60

70

Ato

mic

%

Depth (microns)

Al C Cr Fe Mo N O Ti Co Ni

Chemical analysis: GD-OES

Nitrogen profiles

6

8

10

12

14

16

18

N (

atom

ic %

)

INC-6N INC-7N

4

6

8

10

12

N (

atom

ic %

)

MAR-3N



• MAR-3N shows longer profiles with less nitrogen concentration than INCONELalloys, and a longer diffusion zone.

• Both INCONEL alloys show very similar nitrogen profile, with a plateau of ~ 14-15%of nitrogen content, that decreases drastically .

0,0 0,5 1,0 1,5 2,0 2,5 3,00

2

4

6N (

atom

ic %

)

Depth (microns)

0 2 4 6 8 10 12 14 16 18 200

2

4N (

atom

ic %

)

Depth(microns)

Microscopy: SEM of the fracture

MAR-3 INC-6 INC-7



MAR-3N INC-6N INC-7N

Mechanical properties (Nanoindentation)

• 10 x10 indents, 25 µm space betweenindents• Decreasing Loads from 10 mN to 100 µN

Test parameters



• Decreasing Loads from 10 mN to 100 µN (in 100µN steps)• Loading rate constant• Berkovich Tip radius (150 nm)• E and H � Oliver and Pharr Method

HYSITRON nanoindenter TI950


Er values between 150GPa and 200 GPa for allthe samples.

H values of ~ 10 GPa forMAR-3 and INC-7 and of

REFERENCES (Non nitrided samples): MAR-3, INC-6 & INC-7

MAR-3INC-6INC-7



MAR-3 and INC-7 and of ~ 7 GPa for INC-6.

MAR-3INC-6INC-7

Sample HRc

MAR-3 52.1 ± 0.2

INC-6 17.0 ± 0.2

INC-7 41.8 ± 0.8


Slightly lower Ercompared to the asreceived MAR-3.

MAR-3 & MAR-3N

MAR-3NMAR-3



received MAR-3.

Increase of hardness by40%, especially athigher loads.

MAR-3NMAR-3


Similar Red. Modulus.

Dramatic increase of

INC-6NINC-6

INC-6 & INC-6N



Dramatic increase ofsuperficial hardness(more than x2) withrespect to the asreceived INC-6.

INC-6NINC-6


Similar Red. Modulus

Dramatic increase of

INC-7 & INC-7N

INC-7NINC-7



Dramatic increase ofhardness (x2) withrespect to the asreceived INC-7,especially at higherloads.

INC-7NINC-7

XRD analysis

Cr Kα (λ = 2.29110 Å)BB, 40 KV, 30 mA

Room T, 0.02º step, 0.5 s/step

XRD test conditions

Peaks of Fe4N, FeNi3N,Fe3N and Fe NiN are

MAR-3 & MAR-3N

MAR-3 MAR-3NFe-α (101)



Peaks of Fe4N, FeNi3N,Fe3N and Fe3NiN areobserved.*

There is no austeniticphase 43.64º, 50.76º &74.58º for γ(111), γ(200) &γ(220).

*K. Shetty, S. Kumar, P. Raghothama Rao, Surface & Coatings Technol., 203 (2009) 1530-1536

40 50 60 70 80 90 100 110 120

Fe-α (200)

Fe 3N

Fe 3N

Fe 4N

a.u.

2 Theta

XRD analysis

INC-6 & INC-6N INC-7 & INC-7N

Fe 4N

γ Ν (1

1 1

)

γ Ν (2

0 0

)

γ (2

0 0

)

a.u.

INC-6 INC-6N

γ (111)

CrN

γ Ν (1

1 1

)

γ Ν (2

0 0

)

γ (2

0 0

)

u.a.

INC-7 INC-7N

γ (111)



γ phase is observed in the as received samples, whereas in the nitrided samples amixture of γ and γN phases is present*.

Fe4N is also formed in INC-6N and CrN is observed in INC-7N.

*S. Chollet et al., Surface & Coatings Technol., (2013) In press.

50 55 60 65 70 75 80 85 902 Theta

50 55 60 65 70 75 80 85 90

2 Theta

Wear (Room T)

K wear at room temperature Wear test conditions

Pin-on-disc configurationCounter ball: alumina; Ø = 6 mm

20000 cycles, 2N, 10 cm/sR = 7, 9 and 11 mm

Sample Kwear x10-14 m3/Nm

MAR-3 3.8 ± 0.59

12

15

18

Kw

ear

x10-1

4 m3 /N

m



Nitrided maraging does not show an improvement on wear resistance whereas bothnitrided INCONEL alloys show an improvement of 2 orders of magnitude compared totheir respective non-treated samples.

MAR-3 3.8 ± 0.5

MAR-3N 2.6 ± 0.2

INC-6 14 ± 4

INC-6N 0.099 ± 0.008

INC-7 17 ± 2

INC-7N 0.094 ± 0.010MAR-3 MAR-3N INC-6 INC-6N INC-7 INC-7N

0,00,1

3

6

Kw

ear

x10

Sample

Wear and COF (RT)

MAR-3Wear test conditions


20000 cycles, 2N, 10 cm/sR = 7, 9 and 11 mm

MAR-3N

INC-6 INC-6NSample COF



INC-7N

Sample COF

MAR-3 0.92 ± 0.07

MAR-3N 0.85 ± 0.05

INC-6 0.84 ± 0.06

INC-6N 0.86 ± 0.06

INC-7 0.67 ± 0.07

INC-7N 0.66 ± 0.04

INC-7

Wear and COF (RT)

MAR-3 INC-6 INC-7

500 µµµµm500 µµµµm500 µµµµm



MAR-3N INC-6N INC-7N

500 µµµµm500 µµµµm500 µµµµm

Wear (at 450 ºC)

Wear test conditions


20000 cycles, 2N, 10 cm/s

Sample Kwear x10-14 m3/NmMAR-3MAR-3N INC-6 INC-6N INC-7 INC-7N0

2

4

6

8

10

12

14

16

Kw

ear

x10-1

4 m3 /N

m

Sample



MAR-3 10.5 ± 1.0

MAR-3N 13.2 ± 1.0

INC-6 8.2 ± 3.8

INC-6N 3.1 ± 0.3

INC-7 8.1 ± 2.0

INC-7N 2.7 ± 0.5

MAR-3

MAR-3N

INC-6

INC-6N INC-7N

INC-7Sample

Wear (at 450 ºC)

Wear test conditions


20000 cycles, 2N, 10 cm/s

MAR-3 MAR-3N

INC-6 INC-6N



MAR-3N shows noimprovement comparedto the non treated MAR-3

Nitrided INCONEL alloysshow a slightimprovement.

INC-7 INC-7N

On going work

When comparing withother processes(longer time, highertemperature):

INC-7

0 1 2 3 4 5 6 7 80

2

4

6

8

10

12

14

16

18

N (

atom

ic %

)

500 ºC, 1,5 h 480 ºC, 1,5 h INC-7N



• 480 ºC – 1.5h• 500 ºC – 1.5h

Nanoindentation resultsare similar at high loads,despite the thickernitrided layers of theabove mentionedprocesses.

500 ºC, 1,5h

480 ºC, 1,5h

INC-7N

INC-7

0 1 2 3 4 5 6 7 8

Depth (microns)

On going work

MAR-3

Sample Kwear x10-14 m3/Nm at RT

MAR-3 3.8 ± 0.5

MAR-3N 2.6 ± 0.2

480 ºC-1.5h 1.4 ± 0.50 10 20 30 40 50 60 70 80

0

5

10

15

20

N (

atom

ic %

)

MAR-3N 500 ºC -1.5h 480 ºC -1.5h



When comparing with other processes(longer time, higher temperature):

• 480 ºC – 1.5h• 500 ºC – 1.5h

Longer profiles with higher nitrogenconcentration in the surface are obtained.Tribological tests show a slightimprovement on wear resistance.

500 ºC-1.5h 2.1 ± 0.3

Sample Kwear x10-14 m3/Nm at 450 ºC

MAR-3 10.5 ± 1.0

MAR-3N 13.2 ± 1.0

480 ºC-1.5h 8.1 ± 0.8

500 ºC-1.5h 7.9 ± 0.5

0 10 20 30 40 50 60 70 80

Depth (microns)

Outline

1. Introduction

2. Objectives

3. Methodology





5.Summary

6. Future work

7. Acknowledgments

Summary

Arc activated plasma nitriding processes have been carried out for the nitridingof a series of high nickel content alloys (Maraging 300, INCONEL 600 andINCONEL 718).

Chemical, mechanical, microstructural and tribological analysis of the nontreated and nitrided samples has been done.

Maraging steel 300 has shown long nitriding profiles. The formation of Fe



Maraging steel 300 has shown long nitriding profiles. The formation of Fenitrides explains the superficial hardness increase.

INCONEL alloys 600 and 718 have shown short nitrogen profiles but withnitrogen concentrations up to 14-15%. The formation of γN phase and Fe4N(INC-6N) and CrN (INC-7N) compounds permits to improve wear resistance ofboth alloys 2 order of magnitude at room temperature.

Longer and higher nitrogen profiles are possible to obtain when varying differentprocess parameters (temperature, time,…)

Outline

1. Introduction

2. Objectives

3. Methodology





5. Summary

6.Future work

7. Acknowledgments

Future work

Characterization of corrosion properties ofnitrided samples

EBSD characterization of nitrided samples



EBSD characterization of nitrided samples

Optimization of the nitriding process for eachalloy

Outline

1. Introduction

2. Objectives

3. Methodology





5. Summary

6. Future work

7.Acknowledgments

The authors would like to thank to the Departamento

de Innovación y Empleo of Gobierno de Navarra fortheir support in Super-Maraging project.

Acknowledgments



Thank you for your kind attention!

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