ALWAYS

A recent study, Outokumpu’s datasheets and industrial experience suggest that low-temperature phase separations in super duplex stainless steels (≤550°C), commonly referred to as 475°C-embrittlement, can occur already after 3 min or even shorter times. These short aging times make the super duplex stainless steels very susceptible to hazardous toughness drop after processing such as hot working, welding and hot isostatic pressing. This is therefore a practical concern for the industrial partners in this project. As the transformation occurs on a nano-scale, detection of the phase separation is very difficult by normal destructive and non-destructive testing methods, especially in its early stage. It is believed to be a
contributing factor to unexplained poor toughness and even failure in critical applications. Complex thermal cycles, stresses, as in welding, different material processing routes and a heterogeneous microstructure can introduce conditions that are critical and leading to phase transformations. The project, therefore, is of great
interest to the producers of wrought (Outokumpu Stainless AB), and HIPed steel (Bodycote Hot Isostatic Pressing AB) and producers of welding consumables (ESAB AB) as well as their customers.