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本文研究了一种铁基合金GH_(132)在650℃和一种镍基GH_(33)A合金在750℃的纯蠕变及复杂应力条件下的蠕变及断裂。提出无论是低强度高塑性的GH_(132)合金还是高强度低塑性的GH_(33)A合金在蠕变——疲劳交互作用的复杂应力条件下都将会不同程度地导致材料的弱化而引起过早的断裂。而且这种弱化随应力的升高而加剧。在固定平均应力条件下叠加一个交变应力的动态蠕变与恒定应力的静态蠕变相比较将促使断裂寿命降低。此乃是叠加疲劳促进蠕变断裂的结果。交变应力振幅较小时,对稳态蠕变速率影响不大,控制蠕变第Ⅱ阶段的主要因素是平均应力,但交变应力的振幅较大时将使稳态蠕变速率大大增加。复合交变应力能促进蠕变第Ⅲ阶段的过早来临和试样的过早断裂。
In this paper, the creep and fracture of GH_ (132) iron-based alloy at 650 ℃ and a pure nickel-based GH_ (33) A alloy at 750 ℃ purely creep and complex stress were investigated. It is suggested that GH_ (132) alloy with low strength and high ductility and GH_ (33) A alloy with high ductility and low ductility will be caused by the weakening of materials to some extent under the complex stress conditions of creep-fatigue interaction Broken prematurely. And this weakening aggravates with increasing stress. The dynamic creep of superimposed one alternating stress under the condition of fixed average stress will promote the decrease of the fracture life compared with the static creep of constant stress. This is the result of superimposed fatigue-promoting creep rupture. When the amplitude of alternating stress is small, the steady-state creep rate has little effect. The main factor of the second stage of creep control is the average stress, but when the amplitude of alternating stress is large, the steady-state creep rate will increase greatly. Compound alternating stress can promote the premature creep phase Ⅲ and premature rupture of the sample.