Activation of surfaces prior to gaseous nitriding of a 3wt.% Cr carbon iron-based alloy

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Sébastien JÉGOU, Benjamin GUILLOT, Laurent BARRALLIER - Activation of surfaces prior to gaseous nitriding of a 3wt.% Cr carbon iron-based alloy - In: Nitriding Symposium 4, Etats-Unis, 2016-11-17 - Proceedings of the 4th Nitriding Symposium - 2016

Activation  of  surfaces  prior  to  

gaseous  nitriding  of  a  3wt.%  Cr  

carbon  iron-­based  alloy

Speaker:

Sébastien  Jégou,  Associate  Professor

Arts  et  Métiers  ParisTech,  MSMP  Laboratory

France

L.Barrallier,  Professor,  Arts  et  Métiers  ParisTech,  MSMP  Laboratory

B.Guillot,  PhD,  Arts  et  Métiers  ParisTech,  MSMP  Laboratory

2009 – PhD – Arts et Métiers ParisTech, Aubert & Duval, France

à

Gaseous Nitriding

à

Residual Stresses

2010 – PostDoc – DTU, Denmark

à

Expanded Austenite

à

Nitriding / Carburizing

à

Residual Stresses

2011-­… -­ Associate Professor – Arts et Métiers ParisTech, France

à

Materials Science

à

Surface Engineering

Activation  of  surfaces  prior  to  gaseous  

nitriding  of  a  3wt.%  Cr  carbon  iron-­based  alloy

AGENDA

1. Introduction

2. Experiments

3. Results

Activation  of  surfaces  prior  to  gaseous  

nitriding  of  a  3wt.%  Cr  carbon  iron-­based  alloy

Gas

NH

3

H

2

N

2

Iron-­based  alloy

e

limit  

≈  µm

e

adsorption  

≈  nm

TR A N S P O R T

NH

3

NH

2

N

+

_N

₂

_H

₂

NH

DI F F USI O N

[N]

courtesy  of  Airbus  Helicopters

Gas

NH

3

H

2

N

2

e

limit  

≈  µm

e

adsorption  

≈  nm

TR A N S P O R T

NH

3

NH

2

N

+

_N

₂

_H

₂

NH

DI F F USI O N

[N]

Ex.:

• Contamination  layer

• Reaction  layer

• Deformed  layer

Activation  of  surfaces  prior  to  gaseous  

nitriding  of  a  3wt.%  Cr  carbon  iron-­based  alloy

1.  Introduction  -­ Context

courtesy  of  Bodycote

courtesy  of  Bodycote courtesy  of  Airbus  Helicopters

• Soft  spot

• Lack  of  nitriding

• Heterogeneous  nitriding

Activation  of  surfaces  prior  to  gaseous  

nitriding  of  a  3wt.%  Cr  carbon  iron-­based  alloy

Casting / Forging

Heat Treatments

Machining

Gaseous Nitriding

Activation  of  surfaces  prior  to  gaseous  

nitriding  of  a  3wt.%  Cr  carbon  iron-­based  alloy

Casting / Forging

Heat Treatments

Machining

Gaseous Nitriding

Quality

risks  of  

LOW

Activation  of  surfaces  prior  to  gaseous  

nitriding  of  a  3wt.%  Cr  carbon  iron-­based  alloy

1.  Introduction  -­ Context

Uniformity

Repeatability

•

Surface  hardening

•

Surface  softening

•

Residual  stresses

⇒

Microstructure  transformations

•

Surface  residues

Casting / Forging

Heat Treatments

Machining

Gaseous Nitriding

Surface Preparations

& Controls

•

Cleaning  baths

•

Mechanical  preparations

•

Thermo-­chemical  treatments

SUPERIOR

risks  of  

LOW

Activation  of  surfaces  prior  to  gaseous  

nitriding  of  a  3wt.%  Cr  carbon  iron-­based  alloy

1.  Introduction  -­ Context

Quality

Uniformity

Repeatability

•

Surface  hardening

•

Surface  softening

•

Residual  stresses

⇒

Microstructure  transformations

•

Surface  residues

Surface Preparations

& Controls

•

Cleaning  baths:  residues  from

•

Machining  oil  (sulphate,  phosphate,  silicon,  …)

•

Cleaning  baths  (anionic  surfactant  (sulphonates,  sulphates…))

Activation  of  surfaces  prior  to  gaseous  

nitriding  of  a  3wt.%  Cr  carbon  iron-­based  alloy

Surface Preparations

& Controls

•

Cleaning  baths:  residues  from

•

Machining  oil  (sulphate,  phosphate,  silicon,  …)

•

Cleaning  baths  (anionic  surfactant  (sulphonates,  sulphates…))

Activation  of  surfaces  prior  to  gaseous  

nitriding  of  a  3wt.%  Cr  carbon  iron-­based  alloy

1.  Introduction  -­ Context

•

Mechanical  preparations:  Sandblasting    (sanding)

•

Passivation/corrosion  layer

Surface Preparations

& Controls

•

Cleaning  baths:  residues  from

•

Machining  oil  (sulphate,  phosphate,  silicon,  …)

•

Cleaning  baths  (anionic  surfactant  (sulphonates,  sulphates…))

⇒

Surface  homogeneity  visual  control

⇒

Protection  from  (heterogeneous)  surface  reactions

⇒

Activation  of  the  NH

₃

decomposition

Activation  of  surfaces  prior  to  gaseous  

nitriding  of  a  3wt.%  Cr  carbon  iron-­based  alloy

1.  Introduction  -­ Context

•

Mechanical  preparations:  Sandblasting    (sanding)

•

Passivation/corrosion  layer

•

Heterogeneous  metallurgy/microstructure

•

Thermo-­chemical  treatments:  controlled layer  (nature,  thickness)

•

Oxidization

•

Phosphating  (Zn,  Mn)

1.  Introduction  -­ Context

Surface Preparations

& Controls

•

Thermo-­chemical  treatments:  controlled layer  (nature,  thickness)

•

Oxidization  (NH

₃

decomposition  catalyst)

•

Phosphating  (Zn,  Mn)

⇒

Surface  homogeneity  visual  control

⇒

Protection from  (heterogeneous)  surface  reactions

⇒

Activation of  the  NH

₃

decomposition

Activation  of  surfaces  prior  to  gaseous  

nitriding  of  a  3wt.%  Cr  carbon  iron-­based  alloy

1.  Introduction  -­ Context

Surface Preparations

& Controls

•

Thermo-­chemical  treatments:  controlled layer  (nature,  thickness)

•

Oxidization  (NH

₃

decomposition  catalyst)

•

Phosphating  (Zn,  Mn)

•

Oxidization  :  oxygen  reactivity  with  contaminants

•

Urea

•

NH

₄

Cl

⇒

Surface  homogeneity  visual  control

⇒

Protection from  (heterogeneous)  surface  reactions

⇒

Activation of  the  NH

₃

decomposition

Activation  of  surfaces  prior  to  gaseous  

nitriding  of  a  3wt.%  Cr  carbon  iron-­based  alloy

⇒

Better  Process  Flexibility: In-­situ  pre-­treatments

•

cleaning

•

activation

2.  Experiments

Activation  of  surfaces  prior  to  gaseous  

nitriding  of  a  3wt.%  Cr  carbon  iron-­based  alloy

•

Material:  33CrMoV12-­9

•

17  x  13  x  5  mm

3

•

Austenitized  @  920  °C,  90  min

•

Oil  quenched

•

Tempered  @  640  °C,  1  h

•

Sample  preparation:

•

Degreased

•

Rinsed  in  water

•

Dried  in  alcohol

Composition (wt.%)

C

Cr

Mo

V

Mn

Fe

0.32

2.97

0.84

0.28

0.55

bal.

•

Gaseous  Nitriding:

•

Thermogravimetric  analyser  (Setsys  Evo.)

•

Vacuum  Stages

•

Heating/Cooling  @  10  °C.min

-­1

_{under  N}

2

•

Surface  contamination:

•

Water-­dissolved  machining  oil

•

1  to  100  vol.%

•

1  min  dipping

•

Droplets  removed  

•

In-­situ  treatments:  350-­400  °C,  1  h

•

Vacuum  Stages

•

Oxidization  (O

₂

)

•

Urea  /  NH

₄

Cl

•

200  mg

•

Neutral  atmosphere

3.  Results

0.  The  reference

Activation  of  surfaces  prior  to  gaseous  

nitriding  of  a  3wt.%  Cr  carbon  iron-­based  alloy

Reference

Compound  layer 10  µm 0 50 100 150 200 250 300 300 400 500 600 700 800 900 1000 depth (μm) H V0 .2 Reference Effective depth 135 μm 0 60 120 180 240 300 0 2 4 6 8 10 12 time (min) Ma ss g a in (mg ) Reference Compound layer 10 μm / 105 min / 6.7 mg

3.  Results

a.  Influence  of  water-­dissolved  oil  contaminations

Activation  of  surfaces  prior  to  gaseous  

nitriding  of  a  3wt.%  Cr  carbon  iron-­based  alloy

Sample

Mass gain after

_{nitriding (mg)}

Reference

10.89 ± 0.33

Oil 1 vol.% - a

5.39 (49.5 %)

Oil 1 vol.% - b

5.98 (54.9 %)

Oil 1 vol.% - c

4.16 (38.2 %)

Oil 5 vol.% - a

1.07 (9.8 %)

Oil 5 vol.% - b

5.51 (50.6 %)

0 60 120 180 240 300 0 2 4 6 8 10 12 Ma ss g a in (mg ) Reference Oil - 1 vol.% - a Oil - 1 vol.% - b Oil - 1 vol.% - c Oil - 5 vol.% - a

3.  Results

a.  Influence  of  water-­dissolved  oil  contaminations

Activation  of  surfaces  prior  to  gaseous  

nitriding  of  a  3wt.%  Cr  carbon  iron-­based  alloy

Oil 1 vol.%

Oil 5 vol.%

Reference

Sample

Mass gain after

_{nitriding (mg)}

Reference

10.89 ± 0.33

Oil 1 vol.% - a

5.39 (49.5 %)

Oil 5 vol.% - a

1.07 (9.8 %)

3.  Results

a.  Influence  of  water-­dissolved  oil  contaminations

i.  Oil  1  vol.%

Activation  of  surfaces  prior  to  gaseous  

nitriding  of  a  3wt.%  Cr  carbon  iron-­based  alloy

500 600 700 800 900 1000 H V0 .2 Reference P01 P02 P03 0 50 100 150 200 250 300 0.0 0.2 0.4 0.6 0.8 1.0 1.2 depth (μm) wt.% N Reference B A

3.  Results

a.  Influence  of  water-­dissolved  oil  contaminations

ii.  Oil  5  vol.%

Activation  of  surfaces  prior  to  gaseous  

nitriding  of  a  3wt.%  Cr  carbon  iron-­based  alloy

Compound  layer

0 50 100 150 200 250 300 300 400 500 600 700 800 900 1000 depth (μm) H V0 .2 Reference Oil - 5 vol.%

3.  Results

b.  Influence  of  pre-­oxidization  (O

₂

,  350  °C,  1h)

Activation  of  surfaces  prior  to  gaseous  

nitriding  of  a  3wt.%  Cr  carbon  iron-­based  alloy

0 60 120 180 240 300 0 2 4 6 8 10 12 Ma ss g a in (mg ) Reference Pre-Ox. « Compound  layer »

3.  Results

b.  Influence  of  pre-­oxidization  (O

₂

,  350  °C,  1h)

Activation  of  surfaces  prior  to  gaseous  

nitriding  of  a  3wt.%  Cr  carbon  iron-­based  alloy

0 60 120 180 240 300 0 2 4 6 8 10 12 time (min) Ma ss g a in (mg ) Reference Oil - 1 vol.% - a Oil - 1 vol.% - b Oil - 1 vol.% - c Oil - 1 vol.% - Pre-Ox

0 60 120 180 240 300 0 2 4 6 8 10 12 Ma ss g a in (mg ) Reference

Oil - 5 vol.% (test a) Oil - 5 vol.% (test b) Oil - 5 vol.% - Pre-Ox

3.  Results

b.  Influence  of  pre-­oxidization  (O

₂

,  350  °C,  1h)

Activation  of  surfaces  prior  to  gaseous  

nitriding  of  a  3wt.%  Cr  carbon  iron-­based  alloy

3.  Results

b.  Influence  of  pre-­oxidization  (O

₂

,  350  °C,  1h)

Activation  of  surfaces  prior  to  gaseous  

nitriding  of  a  3wt.%  Cr  carbon  iron-­based  alloy

1 vol.% - Pre-Ox.

1 vol.%

Reference

5 vol.% - Pre-Ox.

5 vol.%

Reference

0 50 100 150 200 250 300 300 400 500 600 700 800 900 1000 depth (μm) H V0 .2 Reference Oil - 1 vol.% (P03) 1 vol.% - Pre-Ox. 0 50 100 150 200 250 300 300 400 500 600 700 800 900 1000 depth (μm) H V0 .2 Reference Oil - 5 vol.% 5 vol.% - Pre-Ox.

0 60 120 180 240 300 0 2 4 6 8 10 12 time (min) Ma ss g a in (mg ) Reference 1 vol.% - Pre-Ox. 5 vol.% - Pre-Ox. 25 vol.% - Pre-Ox. 100 vol.% - Pre-Ox.

3.  Results

b.  Influence  of  pre-­oxidization  (O

₂

,  350  °C,  1h)

Activation  of  surfaces  prior  to  gaseous  

nitriding  of  a  3wt.%  Cr  carbon  iron-­based  alloy

0 2 4 6 8 10 12 Reference 1-vol.% 5-vol.% 25-vol.% 100-vol.% Final-mass-gain-(mg) Pre=Ox. As-nitrided « Compound  layer »

3.  Results

c.  Influence  of  urea

Activation  of  surfaces  prior  to  gaseous  

nitriding  of  a  3wt.%  Cr  carbon  iron-­based  alloy

0 60 120 180 240 300 0 2 4 6 8 10 12 time (min) Ma ss g a in (mg ) Reference 1 vol.% 1 vol.% - Urea 5 vol.% 5 vol.% - Urea 20 vol.% - Urea 0 2 4 6 8 10 12 Reference 1-vol.% 5-vol.% 20-vol.% Final-mass-gain-(mg) Urea As-nitrided « Compound  layer »

3.  Results

c.  Influence  of  urea

Activation  of  surfaces  prior  to  gaseous  

nitriding  of  a  3wt.%  Cr  carbon  iron-­based  alloy

0 50 100 150 200 250 300 300 400 500 600 700 800 900 1000 depth (μm) H V0 .2 Reference 1 vol.% - Urea 5 vol.% - Urea 20 vol.% - Urea 0 60 120 180 240 300 0 2 4 6 8 10 12 time (min) Ma ss g a in (mg ) Reference 1 vol.% 1 vol.% - Urea 5 vol.% 5 vol.% - Urea

3.  Results

d.  Influence  of  NH

₄

Cl

Activation  of  surfaces  prior  to  gaseous  

nitriding  of  a  3wt.%  Cr  carbon  iron-­based  alloy

0 60 120 180 240 300 0 2 4 6 8 10 12 time (min) Ma ss g a in (mg ) Reference 1 vol.% 5 vol.% 5 vol.% - NH₄Cl 20 vol.% - NH4Cl 0 2 4 6 8 10 12 Reference 1-vol.% 5-vol.% 20-vol.% Final-mass-gain-(mg) NH4Cl As-nitrided « Compound  layer »

3.  Results

d.  Influence  of  NH

₄

Cl

Activation  of  surfaces  prior  to  gaseous  

nitriding  of  a  3wt.%  Cr  carbon  iron-­based  alloy

0 50 100 150 200 250 300 300 400 500 600 700 800 900 1000 depth (μm) H V0 .2 Reference NH4Cl 5 vol.% - Urea 20 vol.% - Urea 0 60 120 180 240 300 0 2 4 6 8 10 12 time (min) Ma ss g a in (mg ) Reference 1 vol.% 5 vol.% 5 vol.% - NH₄Cl 20 vol.% - NH4Cl « Compound  layer »

3.  Results

e.  Pre-­treatments  &  residual  stresses

Activation  of  surfaces  prior  to  gaseous  

nitriding  of  a  3wt.%  Cr  carbon  iron-­based  alloy

0 50 100 150 200 250 300 350 400 450 500 –1200 –1000 –800 –600 –400 –200 0 depth (μm) me a n st re ss (MPa ) Reference Pre-Ox. NH₄Cl

0 50 100 150 200 250 300 350 400 450 500 –1200 –1000 –800 –600 –400 –200 0 me a n st re ss (MPa ) Reference Oil - 5 vol.% 5 vol.% - Urea 5 vol.% - Pre-Ox. 5 vol.% - NH₄Cl

3.  Results

e.  Pre-­treatments  &  residual  stresses

Activation  of  surfaces  prior  to  gaseous  

nitriding  of  a  3wt.%  Cr  carbon  iron-­based  alloy

0 50 100 150 200 250 300 350 400 450 500 –1200 –1000 –800 –600 –400 –200 0 depth (μm) me a n st re ss (MPa ) Reference Oil - 5 vol.% 20 vol.% - NH₄Cl

3.  Results

e.  Pre-­treatments  &  residual  stresses

Activation  of  surfaces  prior  to  gaseous  

nitriding  of  a  3wt.%  Cr  carbon  iron-­based  alloy

Activation  of  surfaces  prior  to  gaseous  

nitriding  of  a  3wt.%  Cr  carbon  iron-­based  alloy

4.  Conclusion  

(nitriding  520  °C,  5  h,  K

N

3,7  atm

-­1/2

)

0

5

10

15

20

0

2

4

6

8

10

12

ma

ss

g

a

in

(mg

)

Reference

As nitrided

NH

₄

Cl

Pre-Ox.

Urea

Industry

4.  Conclusion  

(nitriding  520  °C,  5  h,  K

N

3,7  atm

-­1/2

)

Activation  of  surfaces  prior  to  gaseous  

nitriding  of  a  3wt.%  Cr  carbon  iron-­based  alloy

0 200 400 600 800 1000 Reference 1-vol.% 5-vol.% 25-vol.% HV0.2-6 50-µm 0 50 100 150 Reference 1*vol.% 5*vol.% 25*vol.% Effective*depth*(µm) 0 2 4 6 8 10 12 Reference 1-vol.% 5-vol.% 25-vol.% 100-vol.% Final-mass-gain-(mg)

0

2

4

6

8

10

12

Reference

1-vol.%

5-vol.%

25-vol.%

100-vol.%

NH4Cl

Urea

PreAOx.

As-nitrided

•

In-­situ  pre-­treatment:  

•

Urea

•

Oxidization  (thickness  layer  dependence)

•

NH

₄

Cl

•

Advantage:  

•

In-­situ  (during  the  heating  stage)

•

NH

₄

Cl

•

Decomposition  into  NH3  

•

Acidic  cleaning/sanding

efficiency

Activation  of  surfaces  prior  to  gaseous  

nitriding  of  a  3wt.%  Cr  carbon  iron-­based  alloy

Thank  you  for  your  

attention  !

B.Guillot, S.Jégou, L.Barrallier, Degradation of gaseous nitriding of steel by lubricant contamination -­ Effect of