Laser cladding and alloying for refurbishing worn machine parts and improving their surface properties

Refurbishing worn machine parts by applying a new material to the eroded surfaces can be used with the aim not only to replace the worn out material but to obtain surface layers having better service characteristics than those of the original part. Infrared continuous CO2 laser with a maximum power 9 kW was used in the investigation. The laser was equipped with an optical system and a computerized table that allows rotation of the specimen as well as its movement in three directions with a wide range of travel velocities. A direct injection of an alloying powder in the laser beam melted zone at the specimen surface was explored as a way of surface cladding. The powder used for this purpose was a cobalt-base alloy, `Stellite.' The thickness and composition of the clad layers vary significantly with irradiation conditions. A low content of iron (1%) in a clad layer indicates that a significant amount of Stellite powder can be homogeneously introduced. The absence of porosity or cavities in the clad layer as well as at the interface with the substrate was also shown.