工艺参数对触变模锻6061 Al合金微观组织与力学性能的影响

摘要

A new processing technology, powder thixoforming, for preparation of particle reinforced metal matrix composites was proposed and 6061 aluminum alloy was prepared by powder thixoforging. 6061 ingots were first prepared by cold-pressing the atomized 6061 alloy powders, and then the ingots were partially remelted followed by thixoforging. The effects of reheating time, mould temperature and reheating temperature on microstructure and mechanical properties of the thixoforged alloys were investigated. The results indicate that all of the three parameters have large effects on the microstructure and mechanical properties. Owing to the microstructure changes, the fracture regime varies with the processing parameters. Furthermore, cracks always initiate from shrinkage porosities and inclusions, and then propagate either along the secondarily solidified structures or primary particles. The ultimate tensile strength, elongation and hardness of the resulting alloy are up to 196 MPa, 11.0% and HV 55.7 respectively.%提出一种制备颗粒增强金属基复合材料的新技术—粉末触变成形，并利用该技术对基体6061铝合金进行触变模锻。首先，将雾化的6061合金粉末冷压成块，压出的块体作为初始锭料，经部分重熔后再进行触变模锻。研究重熔时间、模具温度和重熔温度对触变模锻6061合金微观组织与力学性能的影响。结果表明，这3个加工工艺参数对微观组织与力学性能均有较大影响；合金的断裂机理是由不同加工工艺参数下的微观组织决定的；此外，裂纹往往起源于缩松和夹杂处，沿着二次凝固组织或者初生相颗粒扩展；经触变模锻得到的合金的抗拉强度、伸长率和硬度分别可达196 MPa、11.0%和HV 55.7。