【摘要】 通过扫描电子显微镜研究了保温时间和缺口半径对DZ951合金热疲劳性能的影响。结果表明,在相同上限温度下,随着保温时间的延长,合金裂纹萌生次数增加,热疲劳抗力提高。铸态合金热疲劳裂纹在碳化物处萌生。热处理合金通过氧化萌生裂纹。裂纹萌生后,主要通过氧化产生孔洞并通过孔洞相互连接使裂纹扩展。热疲劳裂纹沿着与枝晶生长方向呈45°角扩展。热处理合金具有优异的热疲劳性能。随着缺口半径的增加,应力集中减小,合金热疲劳性能提高。更多还原

【Abstract】 Influence of holding time and notched radius of thermal fatigue specimen on thermal fatigue property of DZ951 alloy was investigated by scanning electron microscopy.The results show that the numbers of thermal cycle for crack initiation and resistance of thermal fatigue crack growth increase with the rise of holding time at the same upper temperature.The thermal fatigue crack is initiated at carbide in the as-cast DZ951 alloy and the thermal fatigue crack in heat treated alloy is mainly initiated by oxidized cavities.The connection of oxidized cavities is responsible for thermal fatigue crack propagation.The thermal fatigue crack propagates in direction at an angle of 45° to the orientation of crystal growth.Heat treated alloy exhibits excellent thermal fatigue property.The thermal fatigue property of DZ951 alloy improves with the increase of notched radius of the specimens.更多还原