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Graphite Environment Phase Modelling and Microthermodynamic Response Analysis During the Laser Cladding of Grey Cast Iron
P. Yi, Y-C. Liu, X-H. Zhan, C-F. Fan, T. Liu and P-Y. Xu

The thermodynamic coupling response during the CO2 laser cladding of grey cast iron surface with Fe313 alloy powder is analysed through experiment and numerical simulation. Micromodels and micromodels are established through numerical methods to more effectively acquire the thermal response characteristics of graphite phase and graphite environmental phase. These models enable quantitative analysis on the thermal response of graphite environment phases and establish the relationship of thermal response with local microcracks. Results showed that during the cooling stage of laser cladding, tensile stress is gradually generated around the flake graphite in the bonding zone (BZ). Obvious tensile stress concentration is observed at the graphite tips because of the large temperature gradient, high cooling speed, and different thermophysical parameters among local composition phases. The effects of the main CO2 laser cladding parameters on microcrack extension at the graphite tip are evaluated using an orthogonal test. Scanning speed was found to influence residual tensile stress at the graphite tip more significantly than local preheating and laser power.

Keywords: CO2 laser, HT250 grey cast iron, Fe313 alloy powder, laser cladding, micromodel, graphite environment phase, thermodynamic response, process optimization

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