Abstract
The influences of electron beam (EB) welding and subsequent post-weld heat treatment (PWHT) at different temperatures on the microstructure evolution and low-temperature toughness of duplex stainless steel were investigated. The results showed that the rapid cooling in EB welding led to excessive ferrite formation, abundant Cr2N precipitation, and significant dendritic segregation in the weld, ultimately resulting in deterioration of toughness. PWHT promoted austenite formation and Cr2N dissolution, and eliminated dendrite segregation, which consequently restored the toughness of the weld. The annealing temperature had a very significant influence on the type and content of austenite, as well as toughness. The toughness was not determined solely by the ferrite/austenite ratio. Spheroidal intragranular austenite particles played an important role in improving toughness due to incoherent interface boundaries with the ferrite matrix and low-energy special grain boundaries. The most favourable annealing temperature for the studied EB weld was found to be 1080 °C, at which the weld had the highest impact toughness.
Published Version
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