Influence of process parameters on the residual stress of cladding layers by laser additive manufacturing

In order to study influence rules of process parameters on residual stress distribution of cladding layers, the numerical simulation and experiments test were adopted.The residual stress distribution rules in depth direction of cladding layer section along the scanning path direction (y-direction) and the vertical scanning path direction (x-direction) were obtained.At the same time, the stress field was also analyzed under different process parameters.The results show that the residual stress of y-direction is tensile stress, which is first increasing and then decreasing, and the maximum tensile stress is 262MPa at 0.2mm position from the top of cladding layer.The residual stress of x-direction is from compressive stress converted gradually to tensile stress, which is less than the value of the y-direction stress with the depth of the cladding layer increasing.The x-direction residual stress gradually increases and the y-direction residual stress gradually decreases with the increasing of laser power.The x-direction residual stress gradually decreases and the y-direction residual stress gradually increases with the increasing of scanning speed.The x-direction residual stress and the y-direction residual stress decreases with the increasing of powder mass flow rate.Meanwhile it can provide a method for decreasing residual stress and optimizing process parameters.