Abstract
The mirostructure and mechanical properties of duplex stainless steel (DSS) weldments, consisting of parent material type 2205 UNS S31803 welded using 22Cr - 3Mo - 8Ni filler, were studied after different aging treatments, over the temperature range 450 to 1050 ° C. The results showed that the welded specimens, generally, had lower values of toughness and higher values of hardness, compared to those of the base metal before welding. These observations were explained in terms of non-equilibrium microstructures, and the higher ferrite volume fractions associated with higher cooling rates, in the weld and heat affected zone (HAZ) after welding. The results also showed that both DSS weld metal and parent material are prone to embrittlement when exposed to temperatures between 700 and 1000 ° C, as well as between 450 and 600 ° C. The embrittlement between 700 and 1000 ° C is due to the excessive formation of σ -phase whereas the hardening and embrittlement at 475 ° C are believed to be due to the spinodal decomposition of ferrite into chromium rich and iron rich domains, as well as the formation of the G phase.
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