After a propeller shaft was damaged from chloride in sea water it has been fixed by MAG welding process with flux cored wire. Its service life after welded depends on the corrosion resistance of the weld metal. This research aimed to compare the corrosion resistance of two different weld metals between X111-T5-K4 and E71T-1CH8/T/9M-D flux core wire. The test specimens were prepared according to the ASTM G1-103 standard and tested by salt spray test conforming to the ASTM B 117 standard. The result of the test showed that the corrosion rate of the weld metal using X111-T5-K4 flux cored wire is lower than the weld metal of E71T-1CH8/T/9M-D flux cored wire which was 0.21 and 0.32 mm2/hr. respectively. The mass loss at 24 hours of E71T-1CH8/T/9M-D X111-T5-K4 flux core wire were 0.32 and 0.48 grams respectively. Therefore enhancing the service life of propeller shaft from chloride corrosion should use X111-T5-K4 flux core as weld metal

The damaged propeller shafts caused by the fatigue failure will be repaired by shield metal arc welding process. The service life dependeds on fatigue endurance limit of welding surface. This study was aimed to compare the fatigue resistance of two types of hard facing electrodes using the same arc welding repair process. The investigation of fatigue stress at 517 MPa in failure criteria showed that the propeller shafts repair by Flux core arc welding Process using electrode grade E110T5-K4H4 provided the approximate same service life as that using electrode grade X111-T5-K4 but lowered the repair costs up to thirty-five bath per kilogram electrode. As a result the total maintenance cost decrease 68250 baht per year.