Investigation on the Microporosity Formation of IN718 Alloy during Laser Cladding Based on Cellular Automaton.

Hao Lv,Xudong Li,Hualong Xie,Fei Li,Kun Yang,Zhijie Li

doi:10.3390/ma14040837

Abstract

Porosity is one of the most common defects in the laser cladding of Inconel 718 (IN718) alloy, which can reduce the strength and fatigue performance of the components. However, the dynamic formation of microporosity is challenging to observe through experiments directly. In order to explore the formation mechanism of porosities and dynamically reproduce the competitive growth between porosities and dendrite, a multi-scale numerical model was adopted, combined with a cellular automaton (CA) and finite element method (FEM). The decentered square algorithm was adopted to eliminate crystallographic anisotropy and simulate dendrite growth in different orientations. Afterward, based on the formation mechanism of microporosity during solidification, equiaxed and columnar dendrites with porosities were simulated, respectively. Dendrite morphology, porosity morphology, and distribution of solute concentration were obtained during the solidification process. The simulation results were reasonably compared with experimental data. The simulation results of the equiaxed crystal region are close to the experimental data, but the columnar crystal region has a relative error. Finally, the interaction effects of porosities and dendrites under different environmental conditions were discussed. The results suggested that with the increase in the cooling rate, the quantity of porosity nucleation increased and the porosity decreased.

Highlights

IntroductionLaser cladding (Figure 1) is a kind of additive manufacturing technology, which uses a laser beam to rapidly heat and melt the alloy powder and the surface of the substrate
The competitive growth of columnar crystals was simufor different preferred orientation angles of angles dendrites, as shown in. It can be demonlated for different preferred orientation of dendrites, asFigure shown6.in
A multi-scale numerical model is adopted to simulate the dynamic formation of dendrites during the laser cladding process and porosities, which includes porosity nucleation, dendrite growth, solute redistribution, and diffusion of hydrogen

Summary

Introduction

Laser cladding (Figure 1) is a kind of additive manufacturing technology, which uses a laser beam to rapidly heat and melt the alloy powder and the surface of the substrate. Laser cladding can directly fabricate parts with dense structure, uniform composition, excellent performance [2,3]. It can be applied in the field of repair components [4,5,6]. It has been involved in many industrial areas

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Conclusion