Effects of scanning speed on microstructure in laser surface-melted single crystal superalloy and theoretical analysis

Guowei Wang^1,2，Jingjing Liang¹，Yanhong Yang¹，Yu Shi³，Yizhou Zhou¹，Tao Jin¹，Xiaofeng Sun¹

1. Institute of Metal Research,Chinese Academy of Sciences2. School of Materials Science and Engineering,University of Science and Technology of China3. State Key Laboratory of Advanced Processing and Recycling of Nonferrous Metals,Lanzhou University of Technology

摘 要：Scanning speed is a critical parameter for laser process,which can play a key role in the microstructure evolution of laser melting.In the laser melting of single crystal superalloy,the effects of scanning speed were investigated by experimental analysis and computational simulation.The laser was scanning along710 direction on（001） surface in different speeds.Solidification microstructures of dendrites growth direction and the primary dendritic spacing were analyzed by metallograph.Besides,a planar interface during solidification was taken into attention.Experiment results indicated that the primary dendritic spacing and thickness of planar interface decrease with the increase of speed.Through simulation,distribution of dendrites growth velocity and thermal gradient along dendrite growth direction were calculated,and the simulation of dendrites growth direction agreed with the experiment results.Additionally,a constant value was acquired which can be used to predict the primary dendritic spacing.Moreover,according to curve-fitting method and inequality relation,a model was proposed to predict the thickness of planar interface.

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