The duplex stainless steel was currently an alternative to traditional austenitic stainless steel due to its high strength, acceptable plasticity and lower nickel concentration. The lower nickel concentration made it advantageous as a biomaterial in the human body. The mechanical properties of the duplex steels depended strongly on stresses partitioning between austenitic and ferritic grains as well as morphological and crystallographic textures in ferrite and austenitic phases.
The chemical composition of 2205 duplex stainless steel in weight percent was 0.05 C, 1.05 Mn, 0.022 P, 0.0008 S, 0.75 Si, 21.85 Cr, 5.36 Ni, 3.18 Mo, 0.18 Cu, 0.13 V, 0.054 W, 0.015 Ti, 0.155 N and Fe balance.
The present study investigated the effect of grain refinement of the 2205 duplex stainless steel on its tensile property and corrosion resistance in the chlorine ion environment. The main conclusions were as follows:
1) The ultrafine grained 2205 duplex stainless steel had higher strength and plasticity than coarse grained one.
2) The grain refinement of the 2205 duplex stainless steel inhibited the strain induced α′-martensite transformation and promoted to form more nanotwins.
3) Grain refinement improved corrosion resistance of ultrafine 2205 duplex stainless steel in sodium chloride solution.
4) The grain refinement facilitated the forming of more protective passive films for 2205 duplex stainless steel in the chlorine ion environment.