纯镍挤压制造过程中的磨损行为和显微组织演变

Wear behavior and microstructure evolution in pure nickel extrusion manufacturing

挤压棒材表面形貌和显微组织是决定其力学性能的主要因素。本文作者采用现场挤压和有限元模拟相结合的方法,研究挤压工件的表面磨损行为及显微组织演化机制。结果表明,挤压温度对合金的表面形貌和显微组织有很大的影响。随着挤压温度的升高,磨损机制由磨粒磨损(脆性损伤)转变为粘着磨损(塑性损伤),并且表面粗糙度逐渐增大。挤压过程中坯料的温度和应力呈梯度分布,变形晶粒中的位错墙在激活的滑移系上运动,这导致层状结构产生变形。随着坯料梯度分布幅度和界面摩擦力的增大,层状结构变窄。此外,变形晶粒内几何必要位错的取向梯度也主导5种强理想织构。这些结果为纯镍及镍合金的精确挤压提供了理论依据。

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.