添加Y对富铜纳米相强化铁素体钢拉伸性能的改善

针对富Cu纳米相强化铁素体钢空气时效后拉伸脆断的问题,选取含与不含Y的2种对比合金钢进行相关研究。采用光镜(OM)、扫描电镜(SEM)观测了钢的基体组织、断口及氧化层;高分辨透射电镜(HRTEM)和X射线能谱(EDS)分析了纳米析出相的形貌、尺寸、数量密度、化学成分和晶体结构。结果表明:含Y钢中的含Y富Cu纳米析出粒子平均尺寸变大但数量密度降低,铁素体晶粒变细,钢的拉伸强度、塑韧性改善;Y的拖曳效应使氧化层变薄且钢基体-氧化层、氧化层之间结合牢固。富Cu纳米相强化铁素体钢空气时效后拉伸性能的改善,来源于Y的细化晶粒、抗氧化和净化效果。

Improvement in tensile properties of Cu-rich nano-phase strengthened ferritic steel by addition of Y

Aiming at the problem of tensile brittle fracture for Cu-rich nano-phase strengthened ferritic steel after air aging ,two contrast alloys with and without Y were prepared .The microstructures ,tensile fractures and oxide layers of the alloys were observed by optical microscope (OM ) and scanning electron microscope (SEM ) .High resolution transmission electron microscopy (HRTEM ) and energy dispersive X-ray spectroscopy (EDS) were used to analyze the morphology ,size ,number density ,chemical compositions and crystal structure for nano-crys-talline precipitates .The results show that the average size of Y-containing precipitates in Y-containing steel is lar-ger but the number density is lower ,and the ferrite grain size becomes finer ,thus the tensile strength and plastici-ty as well as toughness are improved .The drag effect of Y makes the oxide layer become thin ,and the matrix-ox-ide layer and oxide layers are firmly combined . The improvement in tensile properties of Cu-rich nano-phase strengthened ferritic steel after air aging is due to the refined grains ,anti-oxidation and purification by the addition of Y .