EFFECT of AUSTINIZING TEMPERATURE and COOLING

2nd. International Symposium on Railway Systems Engineering (ISERSE’13), October 9 to 11, 2013, Karabük, Turkey
EFFECT of AUSTINIZING TEMPERATURE and COOLING
PROCEDURE on WEAR PROPERTIES of
SURFACE HARDENED RAIL
Onur ÖZER*, Buse ÖZTÜRKLER*,Alican ERGÜL*, Harun ÇUĞ*, Faiz MUHAFFEL**
Ġbrahim TOZLU***, Osman YAZAROĞLU***, Hüseyin KOYMATCIK***, Figen DĠKĠLĠTAġ***,
Sait ÖZÇELĠK*, Suleyman YAġIN*, Yavuz SUN*, Hayrettin AHLATCI*
(*)KarabukUniversity, Karabuk, Turkey, [email protected]
(**)Istanbul TecnicalUniversity,Istanbul, Turkey, [email protected]
(***)Kardemir A.ġ., KARABÜK
Abstract
In this study, austenitized Rail Steel and R260 Quality Rail Steel wear behaviors has been examined
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under temperatures of 800 C, 850 C and 900 C by quenching on 10 seconds and 30 seconds.
For this intention block on ring corrosion device and prototype quenching machineries have been
designed and produced. After corrosion test, surface was examined by scanning electron microscope,
profilometer and optic microscope. As a result, low cost, abrasion resistant, higher strength quality rail
manufacturing was implemented[1].
Keywords: rail, wear, surface hardened rail
1. İntroductİon
Due to increasing of population of countries, traffic jam has become the most important problem for
many countries. Railway transportation has an importance regarding to reduce traffic jam significantly.
Duration of access by railway distance of arrival period is able to be reduced beside that it is able to
become more comfortable and safe transportation opportunity. However the effect of environmental
corrosion and heavy tonnage train cause to reduce bench life and increase costs.
Especially, on tight radius bends (less than 2000m is defined tight radius bend) the inner side rails are
able to wear and need to be repaired[2]. In addition, generally rail working life is average between the
20 and 25 years however the inner side rails have to be repaired and changed which are mounted on
tight radius bends. If the process is not carried out it causes to railway traffic congestion and
increased the costs. In Turkey, 34.2% of railways have tight radius bends[3]. In the vicinities in an
advice of International Railway Congress Association to be able to use cork tempered rails[4].
2. Experimental Study
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In this study, rails were austenitized at 850 C and 900 C then subjected to surface hardened by
accelerating cooling with water(w) and air-water (a+w) mixture. These temperatures were selected
due to being closed to rail`s hot rolled temperature. Prototype quenching equipment (Figure 2.1)
enables to be given the water and air-water mixture only head part of rail under 4 bar pressure. The
air which is given to the quenching equipment to be supplied by compressor. The hardened rail and
original rail had been taken to be used on block on ring wear device. After wear tests stereo
microscope, optic microscope and profilometer have been used to indicate wear mechanism.
Özer, O., Öztürkler, B., Ergül, A., Çuğ, H., Muhaffel, F.,
Tozlu, İ., Yazaroğlu, O., Koymatcık, H., Dikilitaş, F., Özçelik, S., Yaşın, S., Sun, Y. and Ahlatci, H.
Figure 2.1. a) Sectional b) 3D design c) manufacture views of cooling system used in head hardening
process[3,5].
3. Results & Discussion
Hardness (HV)
The original rail hardness is 260 HV beside different type of austentizing temperatures during 10s and
30s cooled rails hardness change is Figure 3.1. given. As seen on the figure when austenitization
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temperature is reached 900 C hardness reduced somewhat. As given that condition (austenitization
temperature –ambient), with increasing of quenching time hardness had increased simultaneously.
Hardness process is intended for reducing wearing, increasing the strength during operation
especially on tight and narrow curves against to rolling–contact tumbling[6].
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350
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150
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50
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10 s
30 s
850w
850a+w
900w
900a+w
Quenching Temperature and Type (Water or Air and Water)
Figure 3.1. Hardness values of different quenching conditions (Quenching time 10s and 30s).
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Sliding distance and cumulative weight loss graphs are given in Figure 3.2 and Figure 3.3 for 850 C
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and 900 C. Respectively during the analyse of sliding distance and total weight loss charts initial
3000 m cumulative weight loss increases excessively beside the distance between 3000 m and
12000 m changes linear. The areas are called respectively stringent wearing area and stable wearing
area where cumulative weight loss is excessively and linear.
According to specific sliding distance original specimen demonstrates highest total weight loss beside
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on 850 C and 900 C the specimens which are austenitized has lower total weight loss because of
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reducing quenching. As is spied on the specimen which are hardened on 850 C and water ambient
have lower total weight loss according to specimens which are hardened air-water mixture in the
same time. Specimen which has the 900a+w10 code has the lowest total weight loss between the rest
of rail specimens.
Özer, O., Öztürkler, B., Ergül, A., Çuğ, H., Muhaffel, F.,
Tozlu, İ., Yazaroğlu, O., Koymatcık, H., Dikilitaş, F., Özçelik, S., Yaşın, S., Sun, Y. and Ahlatci, H.
Weight Loss (gr)
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0.02
850w30
0.015
850a+w30
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850w10
850a+w10
0.005
Orijinal
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10000
Distance (m)
15000
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Figure 3.2. Total weight loss-Shifting distance chart which specimen is austenitized on 850 C.
Weight Loss (gr)
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900a+w10
0.015
900a+w30
0.01
900w10
0.005
900w30
Orijinal
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5000
10000
15000
Distance (m)
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Figure 3.3. Total weight loss-Shifting distance chart which specimen is austenitized on 900 C.
Wearing experiments were exanimated according to wear rate of stable area and total weight loss
end of 12 km. Wear rate was calculated according to cumulative weight loss-sliding distance chart
slope between the distance 3000 and 12000 m as a unit of g/m. Figure 3,4 is shown that heat
treatment code with wear rate chance.
High wear rate is seen (Figure 3.4) at original specimen and 850a+w10s specimen. The specimen
which has lowest wear rate is 850w30s. As seen Figure 3.4, while R260 rail exhibited wear rate of
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8,72*10-7gr/m, the 850 C quenched specimen by air-water ambient for 10s had wear rate of 3,59*10o
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7gr/, 850 C quenched specimen for 10s had wear rate of 2,36*10-7 gr/m, 850 C quenched specimen
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by air-water ambient for 30s had wear rate of 1,55*10-7gr/m, 850 C quenched specimen for 30 s had
wear rate of 1,32*10-7 gr/m.
Özer, O., Öztürkler, B., Ergül, A., Çuğ, H., Muhaffel, F.,
Tozlu, İ., Yazaroğlu, O., Koymatcık, H., Dikilitaş, F., Özçelik, S., Yaşın, S., Sun, Y. and Ahlatci, H.
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Wear Rate
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6
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2
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Orj
850/a+w/10
850/w/10
850/a+w/30
850/w/30
Specimen (Water or Air and Water)
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Figure 3.4. Wear rate of specimen which is austenitized 850 C.
Wear rate is shown Figure 3.5. As seen in Figure 3.5, while R260 rail exhibited wear rate of 8,72*100
7gr/m, the 900 C quenched specimen by air-water ambient for 10 s had wear rate of 3,42*10-7gr/m,
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900 C quenched specimen for 10 s had wear rate of 2,47*10-7gr/m, 900 C quenched specimen by
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air-water ambient for 30 s had wear rate of 1,24*10-7gr/m, 900 C quenched specimen for 30 s had
wear rate of 1,51*10-7 gr/m
Wear Rate
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8
6
4
2
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Orj
900/a+w/10 900/w/10 900/a+w/30 900/w/30
Specimen (Water or Air and Water)
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Figure 3.5. Wear rate chart of specimen which is austenitized temperature of 900 C
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Both surfaces view of original specimen and hardened rail specimen at 850 C after wear test. were
shown in Figure 3.6. The results of the depth of wear track was parallel to the total weight loss.. After
examination of surface views obtained that wear on surfaces are abrasive. On the other hand oxide
layer occurred and it caused lower wear strength according to the results of 850w30s and
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850a+w30s. As a result of tests under temperature of 850 C the specimen which has 850w30s code
has the highest wear strength.
Özer, O., Öztürkler, B., Ergül, A., Çuğ, H., Muhaffel, F.,
Tozlu, İ., Yazaroğlu, O., Koymatcık, H., Dikilitaş, F., Özçelik, S., Yaşın, S., Sun, Y. and Ahlatci, H.
X10
X40
Original
850 w 10s
850 w 30s
850 a+w 10s
850 a+w 30s
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Figure 3.6 Wear surfaces of original specimen and hardened rail under temperature of 850 C.
Conclusion
As seen in the wear test, hardness results is parallel to wear strength, oxidation increases wear
strength however formation of abrasion with oxide layer reduce the wear strength.
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As a result of quenching process optimum parameters obtained by quenching from 900 C air-water
for 30 s under laboratory conditions.
Özer, O., Öztürkler, B., Ergül, A., Çuğ, H., Muhaffel, F.,
Tozlu, İ., Yazaroğlu, O., Koymatcık, H., Dikilitaş, F., Özçelik, S., Yaşın, S., Sun, Y. and Ahlatci, H.
Acknowledgment
This study was supported by a support project thesis by “TUBITAK 2209-BIDEP”.
References
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ve Mekanik Özelliklerinin Ġncelenmesi” Yüksek Lisans Tezi 2012
(UIC). http://www.uic.org/
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