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本文研究了第二相对GH33A合金在700℃下,疲劳和蠕变交互作用行为的影响。结果表明,晶界第二相的大小及粒子间距对晶界损伤方式有着很大影响。细小紧密链状分布的晶界第二相,将导致晶界损伤为W型蠕变裂纹。从而使疲劳主裂纹与其前沿的W型裂纹连接扩展成为疲劳蠕变交互作用的主要方式。反之,粗大稀疏的晶界第二相,将使R型蠕变空洞成为其主要晶界损伤方式,也就决定了其疲劳和蠕变交互作用机制主要是主裂纹与其前沿空洞连接扩展。并给出了疲劳裂纹与其前沿R型空洞连接扩展的临界条件:K_L~I≥4αEσ_s(λ-p)。
This paper studies the effect of the second relative fatigue and creep behavior on GH33A alloy at 700 ℃. The results show that the size and intergranular spacing of the second phase in the grain boundary have a great influence on the grain boundary damage mode. The fine and dense chain-like grain boundary second phase will lead to grain boundary damage as W-type creep crack. So that the connection between the main fatigue crack and its W-shaped crack at the leading edge expands into the main mode of fatigue-creep interaction. On the contrary, the coarse and sparse second phase in the grain boundary will cause the R-type creep voids to become the main grain boundary damage mode, which also determines that the interaction mechanism of fatigue and creep is mainly the extension of the main crack and its frontal voids. The critical condition for the extension of the fatigue crack to the frontal R-type cavity is given: K_L ~ I≥4αEσ_s (λ-p).