Corrosion fatigue crack propagation and chromate inhibition of duplex stainless steel

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Saudi Digital Library
The present study was aimed to investigate fatigue crack growth resistance of duplex stainless steel in a corrosive aqueous solution and to examine the effect of chromate inhibition thereof. Fatigue crack growth rates of Zeron 100 duplex stainless steel were measured at a stress ratio of 0.1 in three different environments: air, pure 3.5% NaCl, and chromate (Na2CrO 4) containing 3.5% NaCl solution at 1 Hz frequency under constant amplitude fatigue loading. Two specimen orientations were considered TL and LT. Fatigue crack growth rates in 3.5% NaCl were higher than those in air throughout the range of ΔK tested with greater environmental enhancement in TL orientation. Fracture surface examination revealed ductile fracture at low ΔK and ductile fatigue striations at high ΔK in air for both orientations. At low ΔK values in 3.5% NaCl, austenite exhibited ductile fracture while ferrite showed brittle features. At high ΔK values, however, brittle striations in ferrite and ductile striations in austenite were observed. The effect of inhibition on corrosion fatigue of duplex stainless steel was studied at 0.02M and 0.2M chromate concentrations. (Abstract shortened by UMI.)