Abstract
The microstructure of cobalt-base hardfacing alloys deposited by manual metal arc welding (MMA), tungsten inert gas (TIG) welding, and laser cladding has been investigated as part of a study attempting to establish the relationship between microstructure and abrasive wear properties.
For typical deposition conditions, the differences in freezing rates associated with the three processes are found to give rise to large differences in microstructure. The MMA process gives the largest degree of dilution of the hardfacing deposit; the TIG and laser deposits exhibited much lower levels of mixing with the base plate.
The scale of the microstructure decreases in the order MMA, TIG, and laser cladding, with an associated increase in hardness. It is found that with alumina (Al2O3) as an abrasive, the wear rate persistently is higher with the MMA deposits, the weight loss being approximately linear with time. The laser and TIG deposits, which have more refined microstructures and slightly higher carbon concentrations, both are found to give lower wear rates. Experiments with silicon carbide (SiC) abrasive are also discussed.
The study investigates how different welding techniques influence the abrasive wear resistance of Stellite 6 cobalt-based alloys. Researchers compared samples created through manual metal arc welding, TIG welding, and laser cladding, finding that the cooling rates and resulting microstructures significantly dictate performance.
Using pin-on-disc tests with various abrasives, the authors observed that laser-clad deposits improved their resistance during use due to work hardening, while TIG samples offered the best initial durability. Further analysis via scanning electron microscopy revealed that the coarser structure of arc-welded samples led to the highest rates of material loss.
Metallurgical Transactions A, Vol. 20A, 1989, pp. 1037-1054.
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