Superplastic deformation of commercial OOCr22Ni5Mo3N0.17 duplex stainless steel

Peixue Zhang, Xueping Ren, and Jianxin XieMaterials Science and Engineering School, University of Science and Technology Beijing, Beijing 100083, China

摘 要：<正> The superplastic behavior of a commercial duplex stainless steel has been studied by means of isothermal hot tensile test at temperatures of 850-1050? for the initial strain rates ranging from 3×10-4 s-1 to 5×10-2 s-1. At 960℃, the best superplastic deformation that caused the maximum elongation greater than 840% was obtained for an initial strain rate of 1.2×10-3 s-1. At 850℃, the best elongation 500% was achieved for an initial strain rate of 2.5×10-3 s-1. During the deformation in higher temperature region, coarse y grains formed during the prior treatments were broken into spherical particles, resulting in a homogeneous dispersion of y particles within the ?-ferrite matrix. However, at lower temperatures between 800 and 950℃, the o phase was formed through the eutectoid decomposition of ?-?+?, resulting finally in the stable equiaxed micro-duplex structures with δ/γ and γ/σ, respectively. The precipitation of the o phase played an important role in improving the superplasticity at 850℃.

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