Abstract
In this paper it is mainly presented on corrosion fatigue behavior of the tar epoxy resin coated KA 32 (TMCP) steel for ballast tank based on the corrosion fatigue test results for the notched plate specimen and ultrasonic corrosion fatigue test results for the plane round bar specimen with different tar epoxy resin coating thickness of 50 to 300 μm in an artificial sea water. In higher nominal stress range an effect of tar epoxy resin coating for improvement of corrosion fatigue life was not observed. The lower the stress level, an improving effect for corrosion fatigue life increased. An increase of corrosion fatigue life by tar epoxy resin coating with 200 μm thickness was 2.8 times for that of uncoated specimen at nominal stress range of 199.8 MPa. The thicker the tar epoxy resin coating thickness the longer the fatigue life is.
Electric impedance and capacitance were measured for plate specimen during exposure test and for fatigue test specimen during corrosion fatigue test in an artificial sea water. The degradation of tar epoxy resin coating occurrs at the notched area or the weld toe where the coating absorbed water.
It can be concluded that the improvement of corrosion fatigue strength is not effective when an interception effect disappear due to the breakage or the degradation of the tar epoxy resin coating.
