Mechanical Properties and Corrosion Behavior of Low Carbon Steel Weldments

This research involves studying the mechanical properties and corrosion behavior of low carbon steel (0.077wt% C) before and after welding using Arc, MIG and TIG welding. The mechanical properties include testing of microhardness, tensile strength, the results indicate that microhardness of TIG, MIG welding is more than arc welding, while tensile strength in arc welding more than TIG and MIG.The corrosion behavior of low carbon weldments was performed by potentiostat at scan rate 3mV.sec-1 in 3.5% NaCl to show the polarization resistance and calculate the corrosion rate from data of linear polarization by Tafel extrapolation method. The results indicate that the TIG welding increase the corrosion current density and anodic Tafel slop, while decrease the polarization resistance compared with unwelded low carbon steel. Cyclic polarization were measured to show resistance of specimens to pitting corrosion and to calculate the forward and reveres potentials. The results show shifting the forward, reverse and pitting potentials toward active direction for weldments samples compared with unwelded sample

Experimental and Numerical Study of CO2 Corrosion in Carbon Steel

This research involves study corrosion of low carbon steel under static and flow conditions at 200L/h in the absence and presence of CO2 at two rates 9 and 30 ml/min at four temperatures by electrochemical method using potentiostat. Numerical model was achieved to compare between the experimental and theoretical results to estimate corrosion rate. The results show that the presence of CO2 under static conditions shifts the Ecorr toward noble direction, while under flow condition the presence of CO2 shift Ecorr toward active or noble direction at two rates of gas. The data of corrosion rate in mm/y indicate that the presence of CO2 with two flow rate increased the rate compared with the case of absence of CO2 under static conditions except one case, while under flow conditions, the presence of 9 ml/min. CO2 increases the corrosion rate, while the presence of 30 ml/min. CO2 decreases the rate because of formation FeCO3 scale except at 298K. A Mathematical model was done which show the volumetric flow rate of CO2 and finally the corrosion rate of CO2 correlated with dimensionless groups and independent parameters