29.5.2012 Surface coating

Cladding of Submerged Propeller Shafts: A Comparison Between Conventional and High End Techniques and Materials

The performance of conventional cladding techniques, on the coating of submerged propeller shafts, is analysed and compared against high end techniques. A variety of criteria are used such as mechanical, metallographic and economic in order to obtain a more complete picture. The conventional technique under investigation is Gas Metal Arc Welding (GMAW/MIG) being one of the most established in the field, while the high end counterpart is an emerging technique referred to as Laser Cladding. The mechanical performance is judged in regard to tensile testing with classification society rules in mind. Furthermore, the economic aspects of the operation are examined considering capital investment, labour, welding consumable as well as post welding operations costs. A cladding material often used in suc applications is compared, an austenitic stainles steel AISI 316L. In the case of the conventinal technique, the filler material is in wire form while in the case of the laser technique, metal powder is used. Results indicate that the laser technique presents significant advantages in all respects as faster turnaround can be achieved with less material consumed and lower labour cost. While equivalent if not better mechanical and corrosion properties can be realised.