At present the Cut-stern Kolek Boats of local fishermen at Kaoseng Community on the Coast of Songkhla Lake have a high rate of shaft failure. Consequently, the fishermen have spent lots of money on maintenance program of repairing shafts for a few years. Besides, the repairing cost, each time of the failure also causes water pollution from the leakage of grease. The incomplete transmission of power leads to engine overloading and fuel wasting. The investigation of the high failure rate of propeller shafts which were major machine component in power transmission illustrated the failure in normal fracture caused by the mechanisms of metal fatigue. Using the welding repair by shield metal arc welding process did not give the satisfied outcome because it created the short service life of reused propeller shafts after repairing. This research was aimed to study the metal fatigue behavior of long tail shafts in the Cut-stern Kolek boats and introduce the new method of welding repair process to prolong their service life. The experiment revealed that specimens resulted from the new welding repair process and the conventional one possessed different service life. The new process used the flux core which arc welding can prolong the service life of the shafts of boats more than 1.6 times of using the conventional method which is the electric welding by flux core arc welding. The research result will be extended to fishermen, in order to encourage them to become a part of sustainable inshore fisheries.
This research aimed to investigate the microstructure and hardness properties of hardfacing surface on SCM440 alloy steel by using metal active gas and flux cored arc welding processes. Due to the difficulty of welding the high strength steel, the changes in base metals’ microstructures were found after welding. Preheating the specimens at 350°C and post weld heat treatment the specimens at 550°C were performed for 1 hour, to reduce the residual stresses and avoid the undesired formation of microstructures. The weld metals’ microstructures that were found from both welding processes are acicular ferrite, polygonal ferrite and side plate ferrite. The hardness value of weld metal resulted from flux cored arc welding process is higher than that of the metal active gas welding process. Each welding process produced different quantities of weld metals’ microstructures, causing the difference in hardness values. The data will be used for investigating and improving parameters of shaft repairing, in order to use it more effectively.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.