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EFFECT OF THE TITANIUM CONTENT ON THE INTERNAL FRICTION OF LOW INTERSTITIAL
FERRITIC CHROMIUM STEELS
J. Masmoudi, B. Dubois
To cite this version:
J. Masmoudi, B. Dubois. EFFECT OF THE TITANIUM CONTENT ON THE INTERNAL FRIC-
TION OF LOW INTERSTITIAL FERRITIC CHROMIUM STEELS. Journal de Physique Colloques,
1987, 48 (C8), pp.C8-257-C2-262. �10.1051/jphyscol:1987836�. �jpa-00227140�
JOURNAL D E PHYSIQUE
C o l l o q u e C 8 , supplement au n ° 1 2 , T o m e 4 8 , d e c e m b r e 1987 C8-257
EFFECT OF T H E TITANIUM CONTENT ON T H E INTERNRL FRICTION O F LOW INTERSTITIAL FERRITIC CHROMIUM STEELS
J. M A S M O U D I and B . DUBOIS
Laboratoire de MGtallurgie Rppliguee, Ecole Nationale
Superieure de Chimie de Paris, 11, rue Pierre et Marie Curie, F-75231 Paris Cedex 05, France
RESUME : On etudie 1'influence de la teneur en titane sur des aciers a 13% et 17%
de chrome a tr§s basses teneurs en interstitiels.Apr§s recuit,le frottement interne Q-' est mesurg soit sous champ magn§tique continu.soit en l'absence de champ.
L'effet magnStomecanique est obtenu par soustraction.
Sous champ magnetique, Q—'" .decrolt lorsque la teneur en titane augmente et que,par suite,la taille de grain diminue.
L'effet mapnStomScanique presente deux anomalies:™ fonction de la teneur croissante en titane jcelles—ci ont et£ attributes successivement aux effets du car- bone .puis du phosphore.
ABSTRACT : The influence of the titanium content on low interstitial 13 wt % and 17"Wt£
_]_ chromium steels was investigated.After annealing,the internal friction Q was measured both with and without a direct magnetic field.
The magnetomechanical effect was obtained by subtraction.
Under a magnetic field,Q--1 decreases as the titanium content increases and the grain size decreases.
The magnetomechanical effect showed two anomalies with the increasing of ti- tanium content. Those phenomena were successively related to the carbon and phosphorous contents.
INTRODUCTION: Small quantities of titanium are able to modify the tensile properties, the texture and the corrosion resistance of chromium steels with low car - bon and nitrogen contents(l,2)
According to the carbon.nitrogen,sulphur.phosphorous and titanium content, the last element could be in precipitates or in solid solution in the matrix.
In the liquid state,TiN precipitates are already formed and therefore are always pre- sent in the steels containing titanium.
The carbon atoms could be precipitated as TiC or Ti(CN) .After this stabili- zation,! f theTi content is high enough,Ti sulphides are formed .
The precipitation of Ti.P, also depends on a sufficient titanium content, but mainly on the thermal treatments.
Internal friction experiments were undertaken on a range of ferritic chro- mium steels with different titanium contents(0<% Ti < 0.4 wt% )
The aim of the work was to determine the effect of this element,taking in account its possible reactivity,mainly with minor elements.Due to the ferromagnetism of the studied alloys,it was necessary to apply a saturating direct magnetic field.
(H= 400 OE * 32000 A.m-1 ) .The magnetomechanical contribution Q-1 w as obtained by Ho-Hs
Article published online by EDP Sciences and available at http://dx.doi.org/10.1051/jphyscol:1987836
C8-25 8 JOURNAL DE PHYSIQUE
-1 -1
-
1the subtraction : QHo -Hs = QK,-
-
QR=@ALLOYS STUDIED AND EEERIMENTAL PROCEDURE : At room temperature,measurements of the internal friction Q -1 were carried out on an inverted toision pendulum oscilla- ting at f = 1 Hz.The background was Q-1 = 1.5.10-4
.
A coil was used to apply a saturating magnetic field on the sample (60 x 6 x 0.5 mm3 )The hot rolled chromium steels were kindly supplied by UGINE-ISBERGUES.
The chemical compositions were the following(wt%):
-
17% chromium steels(Tab1e I)C N C r T I P S f?@
Sample 1 0.003 0.005 10.9 0.000 0.017 0.002 0.004 2 0.003 0.008 17.2 0.180 11.017 0.006 0.005 3 0.003 0.005 17.2 0.410 0.019 0.011 0.- 2-2 0.004 0.004 16.9 0.039 O.Ol7 0 0.004 2-4 0.015 0.013 17.0 0.101 0.017 0.001 0 . a
-
13% chromium steels(Tab1e 11)C N C r T i P S tlo
Sample 1-3 0.002 0 . a 12.9 0.000 0.019 0.003 0.004 1-4 0.004 0.004 12.8 0.al' 0.019 0.00s 0.005 1-5 0.003 0.004 12.8 0.433 0.018 0.003 0 . m 1-e 0 . m 0.007 12.9 0 . m o.ore 0.003 0.003 1-9 0.004 0.008 13.0 0.320 0.019 0.004 0.- 2-3 0 . m 0.008 13.1 0.072 0.017 0.002 0.0%
The batches were cold rolled directly with a reduction ratio e0 ' = 80%(eoinitial
thickness,e final thickness) e 0
The sampleswere annealed at different temperatures under pure argon.
-4 hours at 830°C (treatment A) -4 hours at 950°C (treatment B) -4 hours at 1050°~(treatment C) with cooling in the furnace.
The grain size was measured by optical micrography following the A.F.N.O.R. standard.
EXPERIMENTAL RESULTS : The study is mainly focussed on the 17 wt% chromium steels with 80.10-6 < C + N < 110.10-~
.
An exception is made for the alloy 2-4,the carbon and nitrogen content being just below~stoichi~netr~ of Tic and TiN.In this case,we did not detect the Ti sulphide by local analysisonthe SE&l This composition will be indicated by a black point on the curves.Without a magnetic field ,for 17Z chromium steels .after treatment B,
was
d termined as a function of the amplitude E (Fig.1) .*t a given amplitud_e (E =25.10-5dat- ever the annealing temperature
,
there is a minimum value of Q 1 at 0.04 wt% Ti(FiG.2)
Similar results were obtained with 13. wt% Cr steels: the minimum was obtained with 0.07 wt% of titanium.
The direct magnetic field was applied during measurements to exclude the Bloch walls motion( Hs = 400 =).The results are shown on (Fig.3)after annealing at 950°C.
Under a saturating field,the internal friction is low(as shown on the sca1e)and de- creases with the titanium content (Fig.3b).Whatever the thermal treatment the same decrease under H = Hs was obtained(Fig.4).This could be related to a decreaae of the grain size,as measured by optical micrography(Fig.5) .The higher grain sizewas ob- tained without titanium when the annealing temperature increases.The lower inter- nal friction is related to a 0.2 wtXTi content,corresponding to the smaller grain si- ze .This titanium content is often used for the stabilization by the metallurgists (1
-
5).It corresponds to an important nucleation of TiC,TiN or Ti(CN)limiting the grain size.-UP to 0.2wt%Ti,the free titanium is able to modify the matrix proportion or to react witn minor components(du1phideand phosphorous )It is notic.=ble that the increase of the (C + N)content fron1(95&15)10-~ to 280.10-~
yields different results on the Fig.4 and Fig.6,particularly after annealing at83O0C.
The subtraction of the curve 3b from the curve 3a,shows the variation of the magneto- mechanical damping A with the titanium content (Fig.3c).Gn the curve,the minimum va- lue of A (% Ti = 0.05 wt %)appeared related more to the magnetic properties than the dislocationn\otions.These results were found again after annealing at 830°C,butit was not so clear after annealing 1050°~(Fig.6a,b,c).
In the same way,the value of A for % Ti = 0.4% was related to the annealing tempera- ture.
In the case of 13 wt% chromium steels(afte~: thermal treatment A andB),the samephenomena were detected for themap,netomechanicaldampinp; as a function of the titanium content (Fig.7)
A has a minimum value for % Ti =0.07 wt% .Under a saturating magnetic field (Fig.81, after the same annealing treatment,a decrease of ~ ; l = ~ ~ was observed for % T*
0.07 wt%,but a complete comparison with 17% Cr wasnot possibleZperhapsdue to the difference of the chromium content.
DISCUSSION :
A.- The effect of the titanium content in stabilized ferritic chromium steels is more noticeable on the magnetomechanical damping than on the in- ternal friction under a direct magnetic field.
For the coherency of results,we must have 80.10-6 < C + N < 110.10-6
The hypotheses to explain the results are the following:
a)The minimum value of the internal friction observed for
% Ti =0.05 wt% in 17 wt% chromium steels would be related to a fine precipitation of Tic inside large grains(the titanium nitride is already formed in the liquld melt).
These precipitates would be near the stoichiometry:they have been obtained by electro- lytic extraction and identified by X-ray diffraction.We suppose that this is due to their small sizes,after annealing at 830°C and 950°c,they exert a larger effect on the mobility of the Bloch walls rather than on the vibration of dislocations.Due to the coarsening of Tic or Tl(CN) when the titanium content or the annealing temperature increases,this effect becomes less important.(Fig.6C)
JOURNAL DE PHYSIQUE
b
I T I 2
. . . .
IOP 0.1 0 2 0 3 0,4 0,S
O P 0.1 0 2 0.3 0.4 OJ
( a ) (b)
b
I T I OP 0,l 0 2 0.2 0,4 OJ
( c )
o
1
Fig.2-hternalfrictionofalloyswithdiffe-o to a0 30 40 so r e n t c o n t e n t o f t i t a n i u m a n d a t z e r o f i e l d a s
c . l o 6 a f u n c t i o n o f content titanium
(a) a f t e r treatment A Fig.1-Internal f r i c t i o n of a l l o y s with dif- (b) a f t e r treatment B f x tcontent of titanium and a t zero f i e l d (,) a f t e r treatment
c
as a f u n c t i o n o f a m p l i t u d e vibration
Fig.3-Effectof Tiadditiononinternal f m o n of low CJ-17ZCr s t a i n l e s s f o r an constant v i b r a t i o n amplitude(~=25.10-6)
(a) a t H=O
(b) a t H=Hs (H= 400 Oe) (c) a t H=Ho
-
HsF i g . 4 - E f f e c t o f t i t a n i u m c o n t e n t o n i n t e m a l f k i c t i o n under a s a t u r a t i n g f i e l d
(a) a f t e r t h e treatment A (b) a f t e r the treatment B (c) a f t e r the treatment C
Fig.5-Effectof T i additionongrainsize of lowC,N-17%Crstainless forthedifferent
-
treatments
(a) treatment A ; (b) treatment B; (c) treat- ment C
0 to
I T i
-
j
I 1 3 w t % ~ r
j
I.in
0.0 o,l 0.2 0,s 0,4 0,s-
fb)
p
1,% T i
3 '
. . .
. I0.0 0.1 0 2 0.3 0.4 0,5
(a) op0.1 0,203 0.4 0,s
~ig.7-~ffectoftitaniumcontenton magneto- o,n 0.1 o t 03 o,4 0,s
e l a s t i c internal friction
(a) after the treatment A =-Effect of Ticontent onmagnetoelastic
( b ) after the treatment B Internal friction(a) a f t e r treatment A
(b) after treatment B (c) after treatment
c
b o r
OP 0.1 02 0.3 0.4 0,S 0,O 0.1 0,2 0 3 0.4 0,s
Fig.8-~ffectof titaniumcontentoninternal
f -
n under a saturating f i e l d . (a) after the treatment A
(b) a f t e r the treatment B
C8-262 JOURNAL DE PHYSIQUE
Work on magneticpropertiesandT.E.M. is in progress to clarify completely the situation b)When the % Ti= 0.4 wt%,large variations of the internal friction at zero field and of the magnetomechanical effect A were observed,par- ticularly related to the annealing temperature. We assume that for a relatlve high titanium content and a low (C + N ) content,there is a particular reaction with phosphorus .Microanalysis experiments permit us to detect(Ti,Cr,Fe) P,after annea- ling at 830°C and 950°C.At1830"C, few coarse precipitates were observed with no 3 important influence on Q and A. After annealing at 950°C,a large quantity of fine precipitations was detected and it was thought that this produced an impor- tant influence on 9-1 and A, even if the grain size increases ,due to the treatment at this temperatue.The.e phosphides are dissolved after annealing at 1050°C,and their influence on Q-' and A is not well marked even with a large grain size.
B.-Under a saturating magnetic field,the decrease of the internal friction with the titanium content was related to a decrease of the grain size as shown on Fig.4 and Fig.5.
The grain size is controlled by the coarsening of Tic or the formation of Ti(C,N) up to % Ti= 0.18 wt%.Above this percentage,the effect of free titanium is notwll understood,particularly the increase of the grain size-It could be related to an ef- fect of textures.
The changes of the (C + N) content modify the present results as indicated.The re- sults obtained in the case of 13 wt% chromium steels,are similar but the maximum observed at% Ti ~0.05 wt% in
~ i : ~ ~
= f(Ti wt%) may be due to the difference of the chromium content.The titanium suphides were always detected at Ti=0.18 wt%.At lower titanium con- tent,the microanalysis did not permit us to detect MnS,as already suggested(3).
CONCLUSIONS:
The internal friction of low interstitial chromium steels depends on the titanium content used for the stabilization of the steels.However,the effectof the C and P content,on the Bloch wall motion are more important and more complicated than the dislocation vibrations.
REFERENCES:
(1)- T. SAWATANI,K.SHIMIZU,T.NAKAYAMA,M.MIYOSHI Trans.1.S.I.J. 18(1978) 675
(2)-K.MIYAKUSU,Y.UEMATSA,K.HOSHIMO Trans I .S
.
I. J. 26(1986) 231( 3 ) - T. CHANDRA,M.G.ABKEN,J.J.JONAS I.C.S.M.A.6(Melbourne, 1982) 499
(4)-Y .BARBAZANGES ,B .BAROUX,Ph .KRAEMER,Ph .MAITREPIERRE Aciers spEciaux 52 (1980) 1
(5)-T.SAWATANI,K.SHIMIZU.
Trans.1.S.I.J. 18(1978) 687
