Research on variation and stress status of graphite in laser cladding process of grey cast iron

Abstract

Grey cast iron codenamed HT250 was processed by laser cladding with Fe based alloy to investigate the graphite variation in laser cladding process. To study the phenomenon that microcracks appeared at some graphite tips in the bonding zone, the macro laser cladding model and micro graphite model were established. Thermal–mechanical characteristics of the area around graphite were investigated using the models. The results showed that graphite in the bonding zone had complicated variation and microcracks appeared on a portion of graphite tips. Tensile stress concentration emerged at graphite tips in the cooling period which was a hazardous area of microcracks initiation. Microcracks were caused by coactions of microstructure characteristics of graphite area and stress concentration at graphite tips. The tensile stress was closely related to graphite dimensions. Graphite with large radius and length caused larger tensile stress which resulted in microcracks more easily.

Keywords

Laser cladding Graphite Microcrack Stress concentration

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