School of Engineering Sciences and Technology

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Browsing School of Engineering Sciences and Technology by Author "Acharyya, S. G."
  • Item
    Controlling chloride induced stress corrosion cracking of AISI 316L stainless steel by application of buffing
    ( 2019-01-01) Kumar, P. Sunil ; Acharyya, S. G.
    This paper presents the effect of buffing on the stress corrosion cracking (SCC) resistance of machined surfaces of AISI 316L stainless steel (SS). Surface finishing operations are known to lower the SCC resistance of austenitic stainless steels and yet are unavoidable. AISI 316L SS samples were given for different surface finishing operations like turning, milling and grinding. The surface roughness in each case was determined using stylus profiler (contact mode). Lattice strain and phase changes were detected by X-ray diffractometry (XRD) studies. SCC susceptibility has been studied before and after surface buffing operation by exposing to magnesium chloride hexahydrate solution (MgCl2.6H2o) as per ASTM standard procedure G36 for 3h. Microstructural characterization before and after SCC tests were characterize by using field emission SEM (FESEM). Results highlights that AISI 316L SS in turned, milled, and ground condition were highly prone to Cl induced SCC. But on the application of buffing, the SCC resistance of the samples was enhanced and no cracking was observed. Crack enhancement was due to a) reduced surface roughness b) minimum plastic strain and c) high compressive residual stresses generated during buffing operation.
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    Surface working of 304L stainless steel: Impact on microstructure, electrochemical behavior and SCC resistance
    ( 2012-10-01) Acharyya, S. G. ; Khandelwal, A. ; Kain, V. ; Kumar, A. ; Samajdar, I.
    The effect of surface working operations on the microstructure, electrochemical behavior and stress corrosion cracking resistance of 304L stainless steel (SS) was investigated in this study. The material was subjected to (a) solution annealing (b) machining and (c) grinding operations. Microstructural characterization was done using stereo microscopy and electron back scattered diffraction (EBSD) technique. The electrochemical nature of the surfaces in machined, ground and solution annealed condition were studied using potentiodynamic polarization and scanning electrochemical microscopy (SECM) in borate buffer solution. The stress corrosion cracking resistance of 304L SS in different conditions was studied by exposing the samples to boiling MgCl 2 environment. Results revealed that the heavy plastic deformation and residual stresses present near the surface due to machining and grinding operations make 304L SS electrochemically more active and susceptible to stress corrosion cracking. Ground sample showed highest magnitude of current density in the passive potential range followed by machined and solution annealed 304L SS. Micro-electrochemical studies established that surface working promotes localized corrosion along the surface asperities which could lead to crack initiation. © 2012 Elsevier Inc.