IMECH-IR  > 力学所知识产出(1956-2008)
Thesis Advisor洪友士
Degree Grantor中国科学院研究生院
Place of Conferral北京
Keyword疲劳短裂纹 珠光体含量 疲劳寿命 裂纹数密度 等应力试样 Short Fatigue Cracks Volume Fraction Of Pearlite Fatigue Life Crack Numerical Density Iso-stress Specimen
Other Abstract研究短裂纹群体行为是材料疲劳研究的一个重要组成部分。本文研究的是不同珠光体含量的合金结构钢的疲劳短裂纹行为。首先选定实验材料为含碳量为0.1 ~ 0.5%的一个系列的低合金结构钢,并通过相应的热处理工艺,得到铁素体晶粒尺度相近的珠光体-铁素体两相组织。对热处理后的实验材料进行单向拉伸实验,获得其基本力学参数。确定疲劳实验的试样为三角形等应力试样,并采用相应的夹具。然后通过疲劳实验探讨实验材料的疲劳短裂纹数密度演化规律以及珠光体含量对其的影响。通过应力水平不同的疲劳实验研究珠光体含量对材料的疲劳寿命以及疲劳短裂纹阶段占材料疲劳寿命的比例的影响。实验结果表明,这几种实验材料的疲劳短裂纹数密度演化存在着类似的规律,珠光体含量未呈现影响;另一方面,随着珠光体含量的增加,疲劳短裂纹阶段占材料疲劳寿命的比例越来越大,但材料的疲劳寿命却未受其明显影响。最后,对疲劳短裂纹群体行为的随机性进行实验方面的分析,所得结果与理论上数值模拟所得结果在趋势上一致。; The study of the collective damage behavior of short fatigue cracks is very important in the field of fatigue research for materials. This thesis investigates the short fatigue crack behavior of structural steel with different volume fractions of pearlite. First, we choose a series of low-alloy structural steels as experimental materials whose microstructure is composed of ferrite and pearlite. Adopting correspondent heat treatments, we make their ferrite sizes similar. Subsequently, we obtain their basic mechanical parameters through conventional tensile testing. We use the triangular-shaped iso-stress specimen as the specimen of our fatigue test and design the relevant holder. Then we study the evolution of crack numerical density and the effect of the volume fraction of pearlite on it through fatigue test. Through fatigue tests with different stress levels, we study the effect of the volume fraction of pearlite on the fatigue life and the proportion of the short fatigue crack period in the fatigue life. The experimental results show that the evolution of crack numerical density of these experimental materials is similar, whereas the volume fraction of pearlite does not have the effect on it. The results also show that with the increase of the volume fraction of pearlite, the proportion of the short fatigue crack period in the fatigue life increases, but the fatigue life does not increase. At last, we experimentally analyze the randomicity of the collective behavior of the short fatigue cracks. The tendency of the result is consistent with the theoretical one.
Document Type学位论文
Recommended Citation
GB/T 7714
郑亮. 不同珠光体含量的结构钢中的疲劳短裂纹行为研究[D]. 北京. 中国科学院研究生院,1999.
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