Surface Modification of Co-Based Stellite 6 Hardfacings by Laser Surface Melting: Microstructural Evaluation and Reciprocating Wear Resistance
Ali Abdul Munim Alhattab Shaikh Asad Ali Dilawary Amir Motallebzadeh C. Fahir Arisoy Huseyin Cimenoglu
AbstractThis paper aims to investigate the effect of Laser surface melting (LSM) and Mo alloying on plasma transferred arc (PTA) deposited Co-Based Stellite 6 Hardfacings. LSM'ed and Mo alloyed samples were characterized using X-ray diffractometer and scanning electron microscopy. LSM’ed unalloyed Stellite 6 exhibited a microstructure similar to its PTA state in terms of constituent phases but at finer scale as a result of high cooling rate of the melt pool followed the LSM process. Whereas in the LSM’ed Mo-alloyed Stellite 6, only two distinct phases have been observed, whereby the complex carbides appear as interconnected network and the matrix phase appears in fine cellular dendritic morphology. The subsequent LSM process of the unalloyed and Mo-alloyed Stellite 6 led to an increment in the surface hardness as compared to the PTA version. Room temperature wear resistance was examined under testing loads of 1, 2, 3 and 4N and corresponding wear coefficient 'k' was determined. The k values showed that there was almost 25% reduction in wear loss upon the LSM process. This dual approach of Mo alloying and LSM led to a 75% reduction in wear loss than the PTA version.