Conditions for stress corrosion cracking to occur from crevice corrosion sites and related electrochemical features

Abstract

The occurrence of stress corrosion cracking (SCC) from crevice corrosion sites was studied using a kind of occluded U-bend specimen of Type 316L (UNS S31603) stainless steel. It was done in 0.5 M NaCl solution at room temperature and 50 8C. The galvanostatic and potentiostatic polarization methods were adopted. It was found that a tight crevice and high polarization current were the necessary conditions for SCC to occur relative rapidly from crevice corrosion sites. Meanwhile, if there was obvious SCC developing from a crevice corrosion site, the IR drop (or solution resistance) in the crevice path would increase. The increase of IR was attributed to the corrosion product deposition and/or hydrogen bubbles evolved from the cracks. On the other hand, the usually high aspect ratio of stress corrosion cracks, i.e. the inhibited dissolution on the crack walls, might be explained as due to the existence of high IR drops in them.

Theoretical description of the practical possibility of stress corrosion cracking from crevice corrosion sites

“…The crevice in the occluded U-bend specimen used in the experimental work (potentiostatic polarization part) [1] was formed by a contacting method, i.e. placing a silicone rubber crevice former on the end surface of the Araldite resin mounted U-bend specimen.…”

“…In an experimental work [1], stress corrosion cracking (SCC) from crevice corrosion sites was observed at a potentiostatic polarization potential. In that work, a kind of occluded U-bend specimen of Type 316L (UNS S31603) stainless steel was used.…”

“…Based on the experimental work at polarization potential of þ 200 mV SCE [1], the possibility of SCC from a crevice corrosion site in practice can be described as two parts: a. the possibility of sustaining a critical (i.e. above threshold) crevice solution in the crevice corrosion site at the practical corrosion potential (or even lower potential considering the possible drop of corrosion potential when there is crevice corrosion); b. the time for the emergence of a detectable crack at the same potential.…”

Susceptibility of 316L stainless steel to crevice corrosion in submersible solenoid valve

“…In recent years, various electrochemical techniques, such as cyclic potentiodynamic polarization [4][5][6][7][8][9], potentiostatic polarization [4][5][6][7], galvanostatic polarization [10], tsujikawa-hisamatsu method [11], electrochemical noise method [12,13] and dynamic electrochemical impedance spectroscopy [14], are being used to asses the crevice corrosion process. The effects of variables, such as crevice former materials, applied torque on crevice formers, chemical elements and crevice geometries on crevice corrosion behavior, have been studied [4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19][20][21].…”

“…The effects of variables, such as crevice former materials, applied torque on crevice formers, chemical elements and crevice geometries on crevice corrosion behavior, have been studied [4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19][20][21].…”