CAJ | 학술논문

在拉-压疲劳试验机上对室温大气环境下欠时效态、峰时效态、过时效态和自然时效态2A12合金的疲劳行为进行研究,并采用扫描电镜(SEM)分析室温大气环境下不同时效态对疲劳断口形貌的影响.结果表明:在室温大气环境下,四种时效态2A12合金的疲劳断裂循环次数均随着循环应力的减小而明显增加.循环应力水平越低,疲劳寿命提高越明显;各时效态的疲劳断口均为穿晶断口.断口中均出现疲劳条纹、台阶和韧窝,并在较低循环应力下,疲劳条纹出现的区域较多;欠时效态和峰时效态断口上还可观察到轮胎花样.自然时效态表现出最好的疲劳裂纹扩展阻力,其次是欠时效态、峰时效态,过时效态的疲劳裂纹扩展阻力最低.对室温大气环境下各时效态2A12合金疲劳行为进行了讨论.
재랍-압피로시험궤상대실온대기배경하흠시효태、봉시효태、과시효태화자연시효태2A12합금적피로행위진행연구,병채용소묘전경(SEM)분석실온대기배경하불동시효태대피로단구형모적영향.결과표명:재실온대기배경하,사충시효태2A12합금적피로단렬순배차수균수착순배응력적감소이명현증가.순배응력수평월저,피로수명제고월명현;각시효태적피로단구균위천정단구.단구중균출현피로조문、태계화인와,병재교저순배응력하,피로조문출현적구역교다;흠시효태화봉시효태단구상환가관찰도륜태화양.자연시효태표현출최호적피로렬문확전조력,기차시흠시효태、봉시효태,과시효태적피로렬문확전조력최저.대실온대기배경하각시효태2A12합금피로행위진행료토론.
The fatigue behavior of under-aged,peak-aged,over-aged and nature-aged 2A12 alloy in air at room temperature was investigated using a tension-compression fatigue testing machine. The effect of air on the fatigue fractures was studied by means of scanning electron microscopy (SEM). The results showed that the cycle number of fatigue breakdown increased obviously with the cyclic stress decreasing for each aged 2A12 alloy, the lower the cyclic stress level , the more obvious increased the fatigue lifetime, in atmospheric environment with a room temperature. The fractures of every-aged state in air at room temperature are transgranulars, in which fatigue striations,steps and dimples are observed, and more areas with fatigue striations exist under lower cyclic stresses. Tyre-like patterns are observed on fatigue fractures in air for the under-aged and peak-aged. The best fatigue crack growth resistance is revealed at the natural aging state, then it is decreasing in order of the under-aged ,peak-aged state and the over-aged state. The reason for the effect of air on the fatigue behavior of every-aged 2A12 alloy was discussed.