锻态粉末冶金铁基合金的显微组织和力学性能

Microstructure and mechanical properties of hot-forged powder metallurgy Fe-based alloys

采用金相观察、能谱分析、X线衍射和洛氏硬度测定等研究锻态粉末冶金铁基合金显微组织和力学性能演变的规律。研究结果表明：锻造态铁基合金已经开始发生再结晶，但再结晶晶核较少，再结晶不完全，晶界处有第二相析出，析出相成分主要为Ti，Y和O;经1300～1450℃热处理后发生了再结晶，在1300℃再结晶完全，晶粒细小，第二相弥散分布于晶粒内部，样品最高洛氏硬度达54．8；随着热处理温度的提高，晶粒长大明显，强化相颗粒长大，导致洛氏硬度下降；经700℃退火后，铁基合金材料晶粒尺寸变化不明显，X线衍射峰向右发生偏移，Cr的固溶度降低，洛氏硬度下降明显。

The evolution regularity of microstructures and mechanical properties of a forged Fe-based alloy were investigated by optical microstructure, energy spectrum analysis, X-ray diffractrometry and Rockwell hardness testing. The results show that few nucleus of crystal is formed on the forged Fe-based alloy, the grains occur recrystallization and the second phase is composed ofTi, Y and O precipitated at grain boundary. The forged samples occur recrystallization at 1 300-1 450 ℃ through high temperature treatment. The HRC hardness is 54.8 at 1 300 ℃, because there occurs full recrystallization, and the grain size becomes fine, the secondary phase is dispersively distributed within grains. The hardness decreases with the increase of temperature of heat treatment, because the grain size of recrystallization is unchanged but softening occurs. After annealing at 700 ℃, crystal size of the forged Fe-based alloy changes unobviously, and the hardness decreases because of the dextral deviation of X-ray diffraction peak and the decrease of solid solubility of Cr.