在扫描速度低于2mm/s时，熔覆层表面粘接着大量未熔粉末颗粒，降低扫描速度意味着单位路径内增加了粉末总量，而光斑的能量密度恒定，只能熔化有限的粉末量，未熔粉末将通过熔池余热粘接在熔覆层表面。随着扫描速度的增加，熔覆层的熔高、熔宽和熔深均有所减小。

At the scanning speed below 2 mm/s, a large amount of unmelted powder particles are adhered to the surface of the clad layer. Decreasing the scanning speed means that the total amount of powder is increased per unit path, while the energy density of the spot is constant and only a limited amount of powder can be melted, and the unmelted powder will be bonded to the surface of the clad layer by the residual heat of the melt pool. With the increase of scanning speed, the melt height, melt width and melt depth of the clad layer are reduced.