Crack Growth Rates and Corrosion Fatigue of Austenitic Stainless Steels in High Chloride Solutions

Abstract

Purpose: Applications for highly corrosive environments and cyclic loading are often made out of austenitic stainless steels. Corrosion fatigue and crack propagation behaviour has been studied to determine failure processes and damage mechanisms. Approach: CrNiMo stabilized austenitic stainless steel and CrMnN austenitic stainless steel in solution annealed and cold worked condition are compared. S/N curves and crack propagation rate curves are recorded in 43 wt% CaCl2solution at 120 °C, which resembles most severe potential service conditions. For comparison these experiments are also performed in inert glycerine. Additionally, the electrochemical behaviour of these materials has been studied. Findings: The CrMnN steels have excellent mechanical properties but are very susceptible to stress corrosion cracking in the test solution. The fatigue limit as well as the threshold for long crack growth are significantly reduced in corrosive environment. Moreover these steels exhibit a remarkable increase in the propagation rate, which is extremely pronounced in the near threshold region. This effect is enhanced by cold working. CrNiMo steels also show a reduction in the fatigue limit, but it is less pronounced compared to CrMnN steels. The threshold is significantly reduced in corrosive environment, but propagation rate is lower in corrosive environment compared to inert glycerine. Possible explanations of this surprising behaviour are discussed.

Cyclic Crack Growth in Chemically Tailored Isotropic Austenitic Steel Processed by Electron Beam Powder Bed Fusion

“…In the studies of McEvily et al [ 37 , 38 ], the detrimental effect stemming from atmosphere seemed to dominate. Other authors also reported a decreased threshold value for austenitic stainless steels in environments like hydrogen, moist air, or chloride solutions [ 44 , 45 ]. As mentioned above, the data obtained in the present work cannot finally pinpoint the most dominant mechanism responsible for the observed kink in the d a /d N curves.…”

Effect of Polishing on Electrochemical Behavior and Passive Layer Composition of Different Stainless Steels

“…The second, less widely spread group of austenitic stainless steels are the CrMnN austenites, where manganese is the alloying element that stabilizes the fcc lattice. CrMnN has been widely investigated by Speidel and Uggowitzer [ 20 , 21 ] and later by Mori and his group [ 22 , 23 ]. Manganese in contradiction to nickel is less noble than iron and behaves similarly to chromium with its electrochemical potential.…”