Abstract:In the process of laser micro cladding deposition manufacturing of TC4, the influence of the laser power and scanning speed on the microstructure and micro-hardness were analyzed. The results indicate that the prior β columnar grains dominate the entire cladding layer or the columnar are epitaxial growth with a thin layer of fine dendritic microstructure in the top. There are two regions of bright region and dark region in the macrostructure. When P/V is less than 40 W?s?mm-1, the bright region is in the top and the dark region is below it. The microstructure of the two regions is acicular martensite and it is finer in bright region than in dark region. The micro-hardness of the bright region is higher than the dark region and at the same time, when the laser power increased or the scanning speed reduced, the height of the bright region increased and the micro-hardness of the bright and dark region all decreased. Otherwise, the bright region is under the dark region. In this case the microstructure of the bright region is still acicular martensite, and the microstructure of the dark region is coarsened from acicular martensite by a solution and aging treatment of the repeated heating，at the same time the micro-hardness of the dark region is higher than the bright region .