Stress Corrosion Cracking of AISI 304 and AISI 316 Austenitic Stainless Steels in HCl and H2SO4Solutions — Prediction of Time-to-Failure and Criterion for Assessment of SCC Susceptibility

The stress corrosion cracking (SCC) and hydrogen embrittlement (HE) behaviors for types 304, 310, and 316 austenitic stainless steels were investigated in boiling saturated magnesium chloride solutions using a constant load method under different conditions including test temperature, applied stress, and sensitization. Both of type 304 and type 316 stainless steels showed quite similar behavior characteristics, whereas type 310 stainless steel showed a different behavior. The time to failure (tf) parameter was used among other parameters to characterize the materials behavior in the test solution and to develop a mathematical model for predicting the time to failure in the chloride solution. The combination of corrosion curve parameters and fracture surface micrographs gave some explanation for the cracking modes as well as an indication for the cracking mechanisms. On the basis of the results obtained, it was estimated that intergranular cracking was resulted from hydrogen embrittlement due to strain-induced formation of martensite along the grain boundaries, while transgranular cracking took place by propagating cracks nucleated at slip steps by dissolution.

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Investigation of Chloride-Induced Stress Corrosion Cracking for AISI 304/304L Stainless Steel Using Notched Bar Specimens

Volume 6: Materials and Fabrication ◽

10.1115/pvp2020-21399 ◽

2020 ◽

Author(s):

Jae-Yoon Jeong ◽

Yun-Jae Kim ◽

Poh-Sang Lam ◽

Andrew Duncan ◽

Myeong-Woo Lee

Keyword(s):

Finite Element Analysis ◽

Finite Element ◽

Stress Corrosion ◽

Stress Corrosion Cracking ◽

Stainless Steels ◽

Austenitic Stainless Steels ◽

Corrosion Cracking ◽

Element Analysis ◽

Aisi 304 ◽

Induced Stress

Abstract Spent nuclear fuels are stored in dry storage canisters made of austenitic stainless steels. Canisters have a sensitivity to chloride-induced stress corrosion cracking since some storage facilities are located in coastal regions, and this environment could have a higher risk for pits and cracks to form on the surface of canisters. Hence, this paper suggests an experimental method of evaluating crack initiation for austenitic stainless steels. Notched bar specimens fabricated using AISI 304 and 304L stainless steels are designed to simulate loads corresponding to welding residual stresses on the surface of canisters. For testing to be conducted in chloride environments, the developed tester for evaluating CISCC is designed such that the notched bar specimens are immersed into the brine of 5% salinity and are loaded by tightening a spring to provide a constant load condition at 50 °C temperature. Also, initial load applied to each notched specimen is verified using finite element analysis as in the same experimental condition. As a result, the areas by pitting corrosion on notches are 1measured using the Image Analyzer program and the stress parameters obtained from the finite element analysis are used to correlate the effect of the pit formation.

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