Effect of increment and single-track geometry on the formation of multi-track laser cladding

The variation of track geometry during multi-track laser cladding of stellite 6 on mild steel starting with different geometry profiles and levels of dilution in the single-track clad was examined. In transverse cross-section of the multi-track clad, the total area in each track includes the areas of melted powder (clad area), remelted previous track (remelted area) and melted substrate. Both clad area and total area increase with track number and finally reach constant values, but the increase of total area is much greater than that of clad area. The remelted area of previous track increases with the level of dilution of the single-track clad and reaches its maximum value when the dilution of single-track clad is over 20%. The percentage of the maximum remelted area of the previous track equals the percentage of the track overlap. The inter-track porosity will appear when the difference of the total area and the remelted area of the previous track is closer to or smaller than the clad area because there is not enough laser energy to melt the powder captured by the melt pool.