SiCp/AZ91复合材料大口径管材的热挤压成形研究

Hot Extrusion Process of Large Caliber SiCp/AZ91 Composite Pipe

目的解决镁基复合材料大口径管材成形加工困难的问题。方法通过搅拌铸造技术制备的SiC颗粒增强AZ91镁基复合材料百公斤级铸锭坯料,开展了大口径镁基复合材料管材的热挤压成形工艺优化,分析复合材料变形过程中组织与力学性能演变规律,并揭示了其微观机制。结果复合材料管材最佳热挤压工艺参数为:挤压温度为400℃,挤压速度为1 mm/s,在最佳的工艺下成功成形出外径260 mm和130 mm的SiC颗粒增强AZ91镁基复合材料挤压管材,复合材料挤压管材的弹性模量、屈服强度、抗拉强度、伸长率分别可以达到72 GPa,302 MPa,356 MPa,1.2%。结论对温度、挤压比、挤压速度等工艺参数的优化,以及利用SiC颗粒对再结晶行为的促进作用,是制备出大尺寸复合材料管材的关键。

The paper aims to solve the forming and processing problems of large-diameter magnesium matrix composite pipe.Ingot(>100 kg)of SiCp/AZ91 of composites was prepared by stirring casting technology.The hot extrusion process of large caliber magnesium matrix composite pipe was optimized to analyze the changes of microstructure and mechanical properties and reveal the micromechanism during deformation of the composites.The extruded pipes of SiCp/AZ91 composite with outer diameter of 260 mm and 130 mm were successfully formed under the best process(extrusion temperature of 400℃,extrusion speed of 1 mm/s).The elastic modulus,yield strength,tensile strength and elongation of composite extruded pipe can reach 72 GPa,302 MPa,356 MPa,1.2%respectively.Therefore,optimizing process parameters such as temperature,extrusion ratio and speed and making use of the promotion action of SiC particles on recrystallization are the keys to prepare large size composite pipes.