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Stress corrosion cracking of weldments of AISI Type 316 stainless steel
Author(s) -
Shaikh H.,
Khatak H. S.,
Gnanamoorthy J. B.
Publication year - 1987
Publication title -
materials and corrosion
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.487
H-Index - 55
eISSN - 1521-4176
pISSN - 0947-5117
DOI - 10.1002/maco.19870380405
Subject(s) - metallurgy , materials science , intergranular corrosion , gas tungsten arc welding , stress corrosion cracking , austenite , ferrite (magnet) , welding , tungsten , austenitic stainless steel , cathodic protection , corrosion , dissolution , open circuit voltage , cracking , anode , arc welding , composite material , microstructure , electrode , voltage , chemistry , physics , quantum mechanics
The weldments of AISI Type 316 stainless steel prepared by the tungsten inert gas (TIG) and manual metal arc (MMA) welding processes, were tested in a boiling solution of 5 M NaCl + 0.15 M Na 2 SO 4 (pH = 1.3) at an initial stress level of 200 MPa under the open circuit potential (OCP) and the impressed potential (IP) conditions using the constant load technique. Anodic polarisation above the critical cracking potential (CCP) which was determined by the OCP test, accelerated the stress corrosion cracking of both the weldments whereas slight cathodic polarisation below the CCP prevented it. The cracks initiated through pits in both the types of weldments under open circuit as well as impressed potential conditions. The TIG weldments cracked in the heat affected zone whereas the MMA weldments failed in the fusion zone at all potentials. At open circuit potential, the MMA weldments failed by the stress assisted dissolution of delta ferrite, while the TIG weldments failed by the TGSCC of austenite. On anodic polarisation, the MMA weldment failed by the dissolution of delta ferrite and intergranular SCC of austenite, while in the TIG weldments the cracks initiated and propagated in the intergranular mode in the austenite.