The duplex stainless steels are charactrized by two phase structures composed of a mixture of austenite
and ferrite phases. They offer high toughness, good weldability, satisfactory corrosion protection,
excellent stress corrosion cracking resistance and high strength( l-3). Because of these characteristics,
these steels have lbeen widely used in various applications such as oil, gas, and chemical industries.
Duplex stainless steels generally have suffered embrittlement when exposed at elevated temperature,
i.e. above 300°C. To avoid this embrittlement, conventional duplex statinless steels are subject to
solution treatment followed by water quknching in the final stage of production or fabrication, which
limits the size of products. Kim et al.(4) have recently reported that embrittlement can be greatly
reduced by the partial or full replacement’of MO by W in 22Cr-base duplex stainless steels.
For the processing of duplex stainless steel, fusion welding is a major fabrication method for
corrosion resistant applications. Therefore the welding behaviour of these materials has to be fully
defined. During the welding of duplex stainless steels, the welding heat cycle causes a substantial
change of microstucture, compared with the parent material. Important phase transformations take
place particularly in the heat affected zone(HAZ) and significantly influence welding properties such
The purpose of this study is to investigate the effect of MO substitution by W on the impact property
of simulated heat affected zones in 22Cr duplex stainless steels. Structural transformation associated
with MO substitution by W in HAZ has been also investigated on W-containing alloys and
conventional 3% MO duplex stainless steel.