delta/gamma interface boundary sliding as a mechanism for strain accommodation during hot deformation in a duplex stainless steel

In the present work, the mechanical properties and the microstructural evol ution of a duplex stainless steel in the as-cast and wrought conditions dur ing deformation under hot-working conditions have been studied. Hot torsion tests, at strain rates of (epsilon) over dot = 1 s(-1), have been carried out using prepolished samples on which surface parallel scratches have been practiced. The observation of the surface of the samples shows a large dis placement of the scratches produced by two different mechanisms, sliding on the delta/gamma interface, and shearing of the ferrite. The displacements in the as-cast condition have been found to concentrate in a reduced set of ferrite/austenite interfaces leading to the formation of cracks along them . In the wrought material, the distribution of the sliding is more homogene ous over all the ferrite/austenite interfaces, and no damage has been produ ced. These behavioral differences between both materials have been related in the present work, to the characteristics of the corresponding microstruc tures, to the spatial phase distribution, and to the nature of the ferrite/ austenite interface, among others.