Applicability of Friction Stir Welding to steels

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Çam G., İpekoğlu G., KÜÇÜKÖMEROĞLU T., Aktarer S. M.

Journal of Achievements in Materials and Manufacturing Engineering, vol.80, no.2, pp.65-85, 2017 (Scopus)


Purpose: The friction stir welding (FSW) method is widely considered to be one of the most
significant developments in joining technology to emerge in the last 30 years. The technique
has originally been developed for joining difficult-to-fusion-weld Al-alloys, particularly for high
strength grades and now widely used in various industrial applications, such as transport
industries. On the other hand, the application of FSW to high temperature materials such as
steels is hindered due to the problems associated with the stirring tools although there is a
wide interest for the application of this technique to these materials.
Design/methodology/approach: The aim of this review is to address the current
state-of-the-art of FSW of steels, focusing particularly on microstructural aspects and
the resulting properties of these joints and discuss the future prospects of this technique
for steels. For instance, the use of FSW can be advantageous for joining steels in some
special applications where conventional fusion welding processes fail to produce sound
cost effective joints, and the high tooling costs of FSW can be justified (i.e. underwater
joining of steel pipes or hot plate welding in steel mills). In this study, only structural steels
(mainly plain C steels), ferritic stainless steels, austenitic stainless steels and duplex
stainless steels will be considered and the other types of steels are out of the scope of
this work although some examples are included in the discussion.
Research limitations/implications: The tools experience high temperatures in FSW
of steels, i.e., above 1000°C. The number of tool materials which can withstand such
temperatures is very limited. In addition, the welding of many common steels can be
readily conducted by various conventional fusion welding methods. These joining methods
are very flexible, easy-to-perform and well established in industrial applications, which
further prevents the application of FSW to these materials. These limitations are to be
overcome for commercial exploitation of this technique for joining steels.