采用温度场-流场耦合仿真的多道激光熔覆层显微组织调控OA

2205 duplex stainless steel is a commonly used material for valve sealing components,and the density of the laser cladding layer and the balance of the ferrite/austenite phase ratio are key factors affecting the performance after repair.Taking the repair of the internal components of a valve as an example,a three-dimensional transient thermal-flow coupled finite element model for single and multi-pass laser cladding was established to systematically analyze the evolution laws of the molten pool temperature field and flow field,as well as the spatial distribution of solidification characteristic parameters.Multi-pass cladding experiments were conducted using a weaving welding trajectory on a circular ring surface for verification.The results indicate that:the temperature field of single-pass cladding shows a typical umbrella distribution,while the flow field exhibits a symmetrical vortex structure;during multi-pass cladding,the preheating effect of the preceding weld beads leads to a more uniform temperature distribution and a gentler thermal gradient,resulting in an asymmetric complex flow pattern.The cladding experimental results show that the grain growth direction is generally consistent with the heat flow direction,and under the comprehensive consideration of solidification parameters and thermal cycling effects,the microstructure of the cladding layer exhibits small grains,presenting a mixed morphology of cellular and dendritic grains.The research results validate the predictive accuracy of the numerical model,confirming that the cladding layer exhibits typical duplex microstructural characteristics with a balanced phase ratio.