Fatigue crack growth tests on type 321 austenitic stainless steel in corrosive environment and at elevated temperature

Abstract

There are different documents and standards containing fatigue crack propagation limit or design curves and rules for the prediction of crack growth. The background of the curves and the calculations consist of two basic parts: statistical analysis of numerous fatigue crack propagation experiments and fatigue crack propagation law. The research work aimed to measure basic data for limit curves on austenitic stainless steel (type 321), in corrosive environment and at elevated temperatures; and to determine the design curves based on statistical analysis of measured data and the Paris-Erdogan law. Fatigue crack growth tests were performed on modified CT specimens in water solution (30 g CuSO4∗5H2O+10 g NaCl+3 g NaOH in 1000 ml water), at nominally 100 °C and 300 °C testing temperatures. The examinations were executed by constant load amplitude method, the stress ratio was R=0,1, and f=20 Hz frequency was used during the whole tests. In order to study the hold time effect, fatigue crack growth tests were terminated and 3 hours hold time period was applied. The constants of the Paris-Erdogan law were calculated and these values were compared with data can be found in the literature.