FSW IN ALUMINIUM
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Materials Science and Engineering A 496 (2008) 262–268
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Materials Science and Engineering A
journal homepage: www.elsevier.com/locate/msea
Effect of friction stir welding speed on the microstructure and mechanical
properties of a duplex stainless steel
T. Saeid, A. Abdollah-zadeh∗, H. Assadi, F. Malek Ghaini
Tarbiat Modares University, Department of Materials Engineering, P.O. Box 14115-143, Tehran, Iran
a r t i c l e i n f o
Article history:
Received 11 April 2008
Received in revised form 8 May 2008
Accepted 9 May 2008
Keywords:
Friction stir welding
Duplex stainless steel
Microstructure
Mechanical properties
a b s t r a c t
The present study focuses on the effect of the welding speed on the microstructure and mechanical
properties of the stir zone (SZ) in friction stir welding (FSW) of SAF 2205 duplex stainless steel. A single
tool, made of a WC-base material, was used to weld 2 mm-thick plates at a constant rotational speed
of 600 rpm. X-ray radiography revealed that sound welds were successfully obtained for the welding
speeds in the range of 50–200 mm/min, whereas a groove-like defect was formed at the higher speed
of 250 mm/min. Moreover, increasing the welding speed decreased the size of the ˛ and grains in the
SZ, and hence, improved the mean hardness value and the tensile strength of the SZ. These results are
interpreted with respect to interplay between the welding speed and the peak temperature in FSW.
© 2008 Published by Elsevier B.V.
1. Introduction
Duplex stainless steels (DSS) containing both ferrite (˛) and
austenite () phases are increasingly used as alternatives to
austenitic, ferritic stainless steels and nickel-base alloys. They represent
an important and expanding class of steels with an attractive
combination of mechanical properties and corrosion resistance.
This is related to the fact that the microstructure of duplex stainless
steels allows a beneficial mixture of ˛ and properties. High
strength and corrosion resistance come from the ferrite, whereas
the austenite phase influences ductility and resistance to uniform
corrosion [1–4].
In these materials, a good combination of properties is achieved
at an ˛/ ratio of approximately 1:1. However, due to melting and
rapid solidification in fusionwelding processes, this desired ratio is
upset. Also, precipitation of brittle intermetallic phases may occur.
In general, theweldmetal and the heat-affected zone of DSS exhibit
higher ferrite content, coarser grains and more extensive precipitation
of intermetallic phases than
...