Microstructure and mechanical properties of pulsed laser cladded IN718 alloy coating

摘要

The pulsed laser cladded IN718 coatings were fabricated with different scanning speeds of laser cladding, the microstructure and Nb segregation in Laves phase were analysed, the microhardness and the wear resistance of the cladded coatings were investigated. The results showed that the microstructure in the pulsed laser cladded IN718 coating consisted of austenite and interdendritic Laves with Nb concentration over 27 wt-%. The microstructure was refined and Nb concentration in Laves phase was decreased by increasing scanning speed. The microhardness of the as-deposited and the heat-treated coatings was increased with increasing scanning speed due to more Nb dissolving in the austenite during the solidification and increasing main strengthening phase Y ''-Ni3Nb precipitation amount during the heat treatment, respectively. The wear resistance of the pulsed laser cladded IN718 coating was improved by heat treatment and increasing scanning speed, and the wear mechanism was mainly the fatigue wear associated with the abrasive wear.