Abstract:The mechanical properties of extruded bar are dominated by its surface morphology and microstructure. In this study, field extrusion and finite element simulations were combined to study the surface wear behavior and microstructure evolution mechanism of extruded workpieces. The results showed that the extrusion temperature greatly influenced the surface morphology and microstructure. As the extrusion temperature increased, the wear mechanism changed from abrasive wear (brittle damage) to adhesive wear (plastic damage), and the surface roughness gradually increased. During the extrusion, the temperature and stress of the billet presented a gradient distribution, and the dislocation walls in the deformed grains easily moved on the activated slip system, which made the layered structure deformed. With increasing the gradient distribution of the billet and the interface friction, the layered structure became narrower. The orientation gradient of geometrically necessary dislocations in the deformed grain also dominated the five strong ideal textures. These findings provide theoretical support for the precise extrusion of pure nickel and nickel alloys.

Key words: pure nickel; warm extrusion; wear mechanism; layered structure