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Title:	Analysis of stress corrosion cracking below yield loading using boundry element method and polarisation measurement
Authors:	Saber Rashid Ali Trabulsi (P69788)
Supervisor:	Ahmad Kamal Ariffin Mohd Ihsan, Prof. Ir. Dr.
Keywords:	Corrosion and anti-corrosives Universiti Kebangsaan Malaysia -- Dissertations Dissertations, Academic -- Malaysia
Issue Date:	8-Jan-2018
Description:	This study aims to investigate the corrosion phenomena under mechanical loading in 3.5 % Sodium Chloride (NaCl) below the yield stress point, for 304 austenitic stainless steel. A polarisation of corrosion represents the relationship between the corrosion behaviour and mechanical loading. The investigation was divided into three major parts. Firstly, instrumentation was developed to predict the polarisation behaviour, by using ASTM G-38 standard as a reference, which allowed the electrochemical measurements. These measurements were conducted by the potentiodynamic polarisation method. An extrapolation Tafel graph was used to plot the results which explained the reaction at the cathodic and anodic zone. The graph illustrates the behaviour of material based on the electrochemical concept. The displacement was applied to the C-ring specimens where the deflection loading generated the loading stress on the C-ring body. A compression test was conducted on the C-ring specimen to identify the maximum deflection without exceeding the yield point. The stress of C-ring surface was estimated using the finite-element analysis. The second part is the development of the code integrated into the boundary element method (BEM) for stress corrosion simulation. Laplace's equation modelled the potential in the domain. Laplace's equation is solved by the BEM, to obtain the potential and current density on the surface. A computer code is written in FORTRAN for solving Laplace type of problem. The Salome 7.2.0 program was used to process the pre and post calculations. Post-processor generates the information at the geometry is important to capture the details of corrosion problem behaviour. The cases study of stress corrosion using simulated data on the artificial seawater was presented to test the effectiveness of this method. Finally, the validation of the code was conducted by comparing the experimental with simulation results. The applied loads to C-ring specimen towards measure the electrochemical measurement are 0.3 mm, 0.5 mm and 0.7 mm deflections. The results of the finite-element analysis showed the stresses on the C-ring surface are 197.2 MPa, 328.7 MPa and 460.1 MPa, respectively. The highest active corrosion occurred at a 0.7 mm deflection and immersed for 720-hours. The Ecorr value measured was -889.958 mV and ICORR measurement were 232.615 µA, and corrosion rate reached 94.100 MPY. The corrosion rate using a control specimen where no immersion time was applied reached 21.279 MPY. The corrosion rate using the 0.3 mm deflection for the non-immersed specimen and the immersed specimen were 2.201 MPY and 20.453 MPY, respectively. Similarly, the sample with 0.5 mm and 0.7 mm deflection showed the corrosion rate was 68 % greater when immersed. These data demonstrate that the stress has a significant impact on the corrosion behaviour. The results of development the triangles element code showed that the BEM was able to detect the location of the stress corrosion of steel in a domain with precision. For the validation of the simulation results show that this simulation is useful stress corrosion simulation.,Ph.D.
Pages:	135
Call Number:	TA462.T734 2018 3 tesis
Publisher:	UKM, Bangi
Appears in Collections:	Faculty of Engineering and Built Environment / Fakulti Kejuruteraan dan Alam Bina

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