2 results listed
Low carbon steels have been used in a wide
range of shipbuilding applications due to their low
cost, high workability and good weldability.
However, they have relatively low hardness which lead
to low wear resistance. As well known, wear of
engineering materials is an important phenomena and
needs to be improved by any means. It is also well known
that harder materials provide relatively high wear
resistance and low friction coefficient. There are various
ways to enhance the hardness of steels. Grain refinement
by sever plastic deformation (SPD) is one of them.
Among SPD methods, equal channel angular pressing
(ECAP) is one of the most commonly used one due to its
capacity for achieving bulk fine-grained (FG) materials.
According to the available literature, no study has
been performed on tribological properties of FG low
carbon shipbuilding steels via ECAP. Therefore, the
main purpose of this study is to enhance the wear
resistance of a low carbon ship building steel (ASTM
131A) by formation of FG via ECAP. The
tribological behavior of the steel before and after ECAP
was investigated by a reciprocating-type tribometer
(UTS Tribometer T30M-HT). According to the
experimental results, FG formation by ECAP resulted in
a considerable increase in hardness from 130 Hv0.5 to
about 283 Hv0.5. FG formation affected the wear
resistance of the steel. After ECAP, the wear rate of the
steel samples slightly decreased due to the improved
hardness values.
International Iron & Steel Symposium
UDCS
Dursun Murat Sekban
Low carbon steels are well-known ones among
the traditionally shipbuilding materials due to their low
cost, high workability and good weldability. However,
they have relatively low mechanical properties such as
hardness and strength due to their low carbon content.
Grain refinement via sever plastic deformation (SPD)
seems to be an essential strengthening mechanism
without changing the chemical composition of
metallic materials. Among SPD methods, equal
channel angular pressing (ECAP) is one of the most
commonly used one due to its capacity for achieving
bulk ultrafine-grained (UFG) materials. When the
literature is examined, very limited investigations have
been undertaken regarding the low carbon steels and
none of them are shipbuilding steels. Therefore the
mean purpose of this study is to apply ECAP to a
shipbuilding low carbon steel (ASTM 131A) to be able to
achieve finer grained microstructure for gaining
improved mechanical properties. ECAP brought about a
substantial grain refinement. Two different
microstructures observed on flow and transverse
planes of the ECAPed sample. On the flow plane,
microstructure consists of elongated ferrite and
perlite grains aligned in a direction having mainly 45°
angle with the extrusion direction while on the transverse
plane nearly equiaxed grains were formed. Hardness
increased significantly from 130 Hv to about 290 Hv on
the transverse plane after UFG formation. ECAP also
increased both yield and tensile strength values from 280
MPa and 410 MPa to about 420 MPa and 790 MPa,
respectively.
International Iron & Steel Symposium
UDCS
Dursun Murat Sekban
Muhammet Demirtaş
Gençağa Pürçek