Investigation on the columnar-to-equiaxed transition during laser cladding of IN718 alloy

Abstract

In the laser cladding process of IN718 alloy, the growth of microstructure has a great impact on the performance of the alloy material. The study on the columnar-to-equiaxed transition (CET) of IN718 can further understand the formation conditions of the microstructure and control the growth of the microstructure. In this work, the columnar-to-equiaxed transition in the laser cladding process of IN718 was calculated using the Macro-Micro-Coupled Model, establishing the finite element model(FEM) for the macroscopic temperature field of laser cladding and simulating the growth of IN718 alloy microstructure by the cellular automata (CA) method (CA-FEM). It shows that CET will be delayed by increasing laser power, reducing scanning speed, or reducing preheating temperature. Increasing the laser power, reducing the scanning speed, or increasing the preheating temperature will increase the primary dendrite spacing (PDS). Reducing the laser power, increasing the scanning speed, or reducing the preheating temperature will increase the volume fraction of columnar crystals. The height of columnar crystal growth can be determined to be about 220−300μm, the volume fraction of columnar crystals is about 17 %–23 %. The maximum error of simulation is 6.72 %, and the minimum error is 1.69 %.