Thermal and Flow Analysis of Friction Surface Cladding with Varying Clad Layer Thickness

Friction Surfacing Cladding (FSC) is a recently developed, solid-state process to deposit thin metallic clad layers on a substrate. The process employs a hollow rotating tool containing the clad material. The tool is moved along a predefined trajectory at a given distance above the substrate surface while the clad material is pressed out and deposited on the substrate surface beneath the tool. In this study the deposition of a thin layer of AA1050 on an AA2024-T351 substrate was investigated. The study concentrated on the effect of the clad layer thickness on the clad layer profile, the thermal distributions in the FSC tool and the substrate and the generated pressure below the tool. Four cladding experiments were carried out with the nominal layer thickness increasing from 0.2 mmmm to 0.8 mmmm with an increment of 0.2 mmmm. In each experiment the associated supply rate of the clad material and the tool rotation rate were adjusted to obtain a relatively low process temperature of approximately 330 °C that was high enough to manufacture defect free clad layers. The experimental results showed that the manufacturing of thicker clad layers required higher tool rotation rates: from 300 rrrrmm at 0.2 mmmm to 450 rrrrmm at 0.6 mmmm and 0.8 mmmm, but the resulting process induced normal pressure on the substrate decreased from 16.4 MMMMMM to 9.1 MMMMMM. The substrate hardness after the cladding process was hardly affected for all cases. The effect of the clad layer thickness and the tool rotation rate was studied numerically employing a 2D axisymmetric thermal and flow coupled finite element model. The simulation results confirmed the observed trends in the tool rotation rate and the process induced pressure as a function of the nominal layer thickness.