2 results listed
Controlled accelerated cooling of R350HT head
hardened rail joints immediately after their welding is critical in
order to secure that these joints have similar mechanical
properties with the rest of the rail. In practice this accelerated
cooling can be achieved by sending forced air through an
apparatus placed over the welded area of the rail joint just after
welding operation. The apparatus should be designed in a way to
create homogenous and effective cooling around the railhead. For
this purpose, airflow and cooling simulations were performed in
order to optimize the design of such apparatus. Number and
diameter of air nozzles, their positions, nozzle-to-rail surface
distance and airflow rate were employed as the main input
parameters for the simulations performed using ANSYS 15
(thermal and fluid flow). The main focus was on finding the design
and operation parameters that give homogenous air flow around
the rail head which in turn would produce uniform cooling. In this
publication, the results of the simulations run under various
conditions will be compared and an optimum set of design and
operating parameters will be offered.
International Iron & Steel Symposium
UDCS
Nizar Ramadan
Kazım Tur
Erkan Konca
The interest in austempered ductile irons (ADI) is
continuously increasing due to their various advantageous
properties over conventional ductile irons and some steels. This
study aimed at finding the roles of alloying elements, namely Ni,
Cu and Mo, on the austemperability of GGG-60 ductile cast iron.
Two different sets of GGG-60 (EN-GJS-600-3) ductile iron
samples, where one set was alloyed with Ni and Cu and the other
set was alloyed with Mo, Ni and Cu, were subjected to
austempering treatments at 290-350°C. A custom design heat
treatment setup, consisting of two units where the top unit
(furnace) serving for austenitizing and the 200-liter capacity
bottom unit (stirred NaNO2-KNO3 salt bath) serving for
isothermal treatment, was used for the experiments. It has been
found that austempering treatment at 290°C increased the
hardness of the Ni-Cu alloyed GGG-60 sample by about 44%
without causing a loss in its ductility. In the case of Mo-Ni-Cu
alloyed sample, the increase in hardness due to austempering
reached to 80% at the same austempering temperature while some
ductility was lost. Here, the microstructural investigation and
mechanical testing results of the austempered samples are
presented and the role of alloying elements (Mo, Ni, and Cu) on
the austemperability of GGG-60 is discussed.
International Iron & Steel Symposium
UDCS
Erkan Konca
Kazım Tur
Erkin KOÇ