Abstract

Low temperature surface engineering of stainless steels by dissolving large quantities of nitrogen and carbon has become a favorable technological process. Such treatments usually yield the so-called expanded austenite, which is a super-saturated diffusion zone and can be produced by a salt, gas, or plasma-based processes. The present manuscript addressed the production of expanded austenite on a superaustenitic stainless steel at low temperature. Gas mixtures with nitrogen or both nitrogen and carbon bearing gases were applied in a plasma atmosphere at 400°C for 5 h. Microstructural characterization was conducted applying light optical microscopy, X-ray diffraction, and transmission electron microscopy. In addition, microhardness measurements were performed at the surface of the samples. Plasma nitriding and nitrocarburising at 400°C resulted in a homogeneous case composed solely by expanded austenite as detected by X-ray diffraction. Similar microhardness was observed for both processes, whereas nitrocarburising provided a thicker diffusion zone when compared to nitriding. Fine iron-chromium nitride precipitation was only identified by transmission electron microscopy (TEM). Selected area electron diffraction yields similar lattice parameters for both processes.

References

1.
Heino
,
S.
and
Karlsson
,
B.
, “
Cyclic Deformation and Fatigue Behaviour of 7Mo-0.5N Superaustenitic Stainless Steel - Stress-Strain Relations and Fatigue Life
,”
Acta Mater.
, Vol.
49
, No.
2
,
2001
, pp.
339
351
. https://doi.org/10.1016/S1359-6454(00)00201-9
2.
Heino
,
S.
, “
Role of Mo and W During Sensitization of Superaustenitic Stainless Steel-Crystallography and Composition of Precipitates
,”
Metall. Mater. Trans. A
, Vol.
31
, No.
8
,
2000
, pp.
1893
1905
. https://doi.org/10.1007/s11661-000-0217-9
3.
Dong
,
H.
, “
S-Phase Surface Engineering of Fe-Cr, Co-Cr and Ni-Cr Alloys
,”
Int. Mater. Rev.
, Vol.
55
, No.
2
,
2010
, pp.
65
98
. https://doi.org/10.1179/095066009X12572530170589
4.
Fernandes
,
F. A. P.
,
Heck
,
S. C.
,
Pereira
,
R. G.
,
Picon
,
C. A.
,
Nascente
,
P. A. P.
, and
Casteletti
,
C.
, “
Ion Nitriding of a Superaustenitic Stainless Steel: Wear and Corrosion Characterization
,”
Surf. Coat. Technol.
, Vol.
204
, Nos.
18–19
,
2010
, pp.
3087
3090
. https://doi.org/10.1016/j.surfcoat.2010.02.064
5.
Li
,
X. Y.
, “
Low Temperature Plasma Nitriding of 316 Stainless Steel: Nature of “S” Phase and its Thermal Stability
,”
Surf. Eng.
, Vol.
17
, No.
2
,
2001
, pp.
147
152
. https://doi.org/10.1179/026708401101517746
6.
Williams
,
D. B.
and
Barry Carter
,
C.
,
Transmission Electron Microscopy: A Textbook for Materials Science
, 2nd ed.,
Springer Science and Business Media LLC
,
New York
,
2009
.
7.
Christiansen
,
T. L.
and
Somers
,
M. A. J.
, “
Determination of the Concentration Dependent Diffusion Coefficient of Nitrogen in Expanded Austenite
,”
Int. J. Mater. Res.
, Vol.
99
, No.
09
,
2008
, pp.
999
1005
. https://doi.org/10.3139/146.101729
8.
Fernandes
,
F. A. P.
,
Christiansen
,
T. L.
,
Winther
,
G.
, and
Somers
,
M. A. J.
, “
On the Determination of Stress Profiles in Expanded Austenite by Grazing Incidence X-Ray Diffraction and Successive Layer Removal
,”
Acta Mater.
, Vol.
94
,
2015
, pp.
271
280
. https://doi.org/10.1016/j.actamat.2015.04.040
9.
Christiansen
,
T. L.
and
Somers
,
M. A. J.
, “
On the Crystallographic Structure of S-Phase
,”
Scr. Mater.
, Vol.
50
, No.
1
,
2004
, pp.
35
37
. https://doi.org/10.1016/j.scriptamat.2003.09.042
10.
Totten
,
G. E.
,
Casteletti
,
L. C.
,
Fernandes
,
F. A. P.
, and
Gallego
,
J.
, “
Microstructural Characterization of Layers Produced by Plasma Nitriding on Austenitic and Superaustenitic Stainless Steel Grades
,”
J. ASTM Int.
, Vol.
9
, No.
2
,
2012
, pp.
1
11
. https://doi.org/10.1520/JAI103564
11.
Fernandes
,
F. A. P.
,
Casteletti
,
L. C.
, and
Gallego
,
J.
, “
Microstructure of Nitrided and Nitrocarburized Layers Produced on a Superaustenitic Stainless Steel
,”
J. Mater. Res. Technol.
, Vol.
2
, No.
2
,
2013
, pp.
158
164
. https://doi.org/10.1016/j.jmrt.2013.01.007
12.
Raghavan
,
V.
, “
The Cr-Fe-N-Ni System
,”
J. Phase Equilib.
, Vol.
18
,
1997
, pp.
158
172
. https://doi.org/10.1007/BF02665700https://doi.org/10.1007/BF02665700
13.
Rivière
,
J. P.
,
Templier
,
C.
,
Declémy
,
A.
,
Redjdal
,
O.
,
Chumlyakov
,
Y.
, and
Abrasonis
,
G.
, “
Microstructure of Expanded Austenite in Ion-Nitrided AISI 316L Single Crystals
,”
Surf. Coat. Technol.
, Vol.
201
, No.
19
,
2007
, pp.
8210
8214
. https://doi.org/10.1016/j.surfcoat.2006.01.080
14.
Xu
,
X. L.
,
Wang
,
L.
,
Yu
,
Z. W.
, and
Hei
,
Z. K.
, “
Microstructural Characterization of Plasma Nitrided Austenitic Stainless Steel
,”
Surf. Coat. Technol.
, Vol.
132
, Nos.
2–3
,
2000
, pp.
270
274
. https://doi.org/10.1016/S0257-8972(00)00905-1
15.
He
,
Y.
,
Li
,
Z.
,
Qi
,
H.
, and
Gao
,
W.
, “
Standard Free Energy Change of Formation per Unit Volume: A New Parameter for Evaluating Nucleation and Growth of Oxides, Sulphides, Carbides and Nitrides
,”
Mater. Res. Innov.
, Vol.
1
, No.
3
,
1997
, pp.
157
160
. https://doi.org/10.1007/s100190050034
16.
Manova
,
D.
,
Eichentopf
,
I.-M.
,
Hirsch
,
D.
,
Mändl
,
S.
,
Neumann
,
H.
, and
Rauschenbach
,
B.
, “
Influence of Microstructure on Nitriding Properties of Stainless Steel
,”
IEEE Trans. Plasma Sci.
, Vol.
34
, No.
4
,
2006
, pp.
1136
1140
. https://doi.org/10.1109/TPS.2006.877746
17.
Mitchell
,
D. R. G.
,
Attard
,
D. J.
,
Collins
,
G. A.
, and
Short
,
K. T.
, “
Characterisation of PI3 and RF Plasma Nitrided Austenitic Stainless Steels Using Plan and Cross-Sectional TEM Techniques
,”
Surf. Coat. Technol.
, Vol.
165
, No.
2
,
2003
, pp.
107
118
. https://doi.org/10.1016/S0257-8972(02)00741-7
18.
Xu
,
X.
,
Wang
,
L.
,
Yu
,
Z.
,
Qiang
,
J.
, and
Hei
,
Z.
, “
Study of Microstructure of Low-Temperature Plasma-Nitrided AISI 304 Stainless Steel
,”
Metall. Mater. Trans. A
, Vol.
31
, No.
4
,
2000
, pp.
1193
1199
. https://doi.org/10.1007/s11661-000-0115-1
19.
Natishan
,
P. M.
,
Bayles
,
R. A.
,
Rayne
,
R.
,
Longazel
,
T.
,
Martin
,
F. J.
,
Kahn
,
H.
, and
Heuer
,
A. H.
, “
Interstitial Hardening of Type 316L Stainless Steel to Improve Corrosion Resistance and Mechanical Properties
,”
Corrosion
, Vol.
68
, No.
7
,
2012
, pp.
638
644
. https://doi.org/10.5006/0599
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