枝晶间一次相对熔铸GH136合金低周疲劳性能的影响

本文对熔铸GH136合金的研究结果表明:存在于枝晶间的大的未溶一次相粒子能降低材料的低周疲劳性能。粒子的作用机构有两个,其一是激发主裂纹的早期萌生,其二是自身形成内疲劳源,通过内源的生长及与主裂纹的联结加速材料的破坏。 这两种作用机构均与裂纹扩展速率有关。在高裂纹扩展速率下(或高应力幅值),粒子的有害作用被减弱,反之,其有害作用加强。采用提高固溶温度的方法可以有效地去除这些一次相粒子,使材料在低交变应力范围的性能得以改善。

The Influence of Primary Particles on the Property of Low Cycle Fatigue in Kl36 ECD

This investigation indicates that the primary dendritic particles lower significantly the property of low cycle fatigue in K136 ECD (Est-Cast-to-Shape Disc). The possible reason for this phenomenon is as following.(1) Arousing the main crack to early form;( 2 ) Acting as internal source of fatigue cracks. These both effects depend on the fatigue stress and fatigue crack growth rate. Under the condition of high fatigue stress or higher crack growth rate this detrimental effect can be reduced. However, if the fatigue stress is lower, the primary dendritic larger particles decrease the fracture life significantly. Increasing solid solution temperature can decrease the number of primary particles resulting in the improvement of fatigue porperty.