Underwater friction stir welding has attained a wide popularity nowadays. This innovative process is a variant of the friction stir welding process in which the specimen and the specimen-tool interface are submerged completely inside the water. Even though the heat dissipated in a friction stir welding process is proved to be comparatively less than arc welding process, the prime intention to investigate underwater friction stir welding process by the research community is to reduce the heat generated and thereby anticipated to have enhanced mechanical characteristic weld joint. Two major drawbacks of commercializing the underwater friction stir welding process are complexity as a result of weld path and fixture design. Therefore, in this research, underwater friction stir welding and traditional friction stir welding are performed on AA 6063 pipe joints with unique developed fixtures. The fixtures are designed and fabricated for holding the two pipes firmly. Welding parameters are established initially by conducting several trials for obtaining quality welds. A very rare literature on underwater friction stir welding of pipes is the motivation to investigate its adaptability and mechanical characteristics. The results prove that there is an evident depreciation in the tensile strength and hardness in the joints welded using both processes compared to the base material. However, underwater friction stir welding has exhibited a high tensile strength of 218 MPa and nugget zone hardness of 83 VHN compared to the traditional process that has 201 MPa and 65 VHN respectively. Quality flawless welds produced indicate their suitability of underwater friction stir process for welding pipes. |
