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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。
The effect of holding time and notch radius on the thermal fatigue properties of DZ951 alloy was studied by scanning electron microscopy. The results show that under the same upper limit temperature, with the increase of holding time, the number of crack initiation increases and the thermal fatigue resistance increases. Thermal fatigue cracks in as-cast alloys initiate at carbides. Heat treatment of the alloy through the initiation of oxidation cracks. Crack initiation, the main hole by oxidation and interconnection through holes to crack propagation. Thermal fatigue cracks propagate at an angle of 45 ° to the direction of dendrite growth. Heat-treated alloys have excellent thermal fatigue properties. As the notch radius increases, the stress concentration decreases and the thermal fatigue properties of the alloy increase.