The cleavage rupture behaviour of the Ti alloy TC11 with various microstructures,i.e., equiaxed,duplex and interweaving,has been studied under fatigue-creep interaction at 520℃.It was found to be not only related to ...The cleavage rupture behaviour of the Ti alloy TC11 with various microstructures,i.e., equiaxed,duplex and interweaving,has been studied under fatigue-creep interaction at 520℃.It was found to be not only related to the rate of creep void initiating,but also control- led by the creep strain accumulation on holding under tension test and stress state at crack-tip.This seem to be combinably offected by both value of critic void initiating strain and parameter,V_(GC),of critic void growth.展开更多
In Situ observation of deformation and fracture for superalloy GH169 under combined fatigue-creep action is made by using high temperature metalloscope,it is shown that under the test conditions the deformution takes ...In Situ observation of deformation and fracture for superalloy GH169 under combined fatigue-creep action is made by using high temperature metalloscope,it is shown that under the test conditions the deformution takes place by merely of slipping,twinning and grain houndary sliding,and the mode of failure depends on the microstructure of specimen. lntergranular cracks arise.from W-type voids produced by the stress concentration at triple point which could not be relaxed by the interior deformation of grains and the local deformathm region along grain bounaries.And the crack propagation mechanism is the nucleation,growth and linkage of carities at the grain boundaries.Transgranular cracks form from deformatiom damages within the grain,and its propagation mechanism is shear rupture along the slip phme.展开更多
AISI H13 （4Cr5MoSiV1） is one of the commonly used materials for extrusion tool, and it suffers from fatigue-creep damage during the hot extrusion process. Stress-controlled fatigue and creep-fatigue interaction test...AISI H13 （4Cr5MoSiV1） is one of the commonly used materials for extrusion tool, and it suffers from fatigue-creep damage during the hot extrusion process. Stress-controlled fatigue and creep-fatigue interaction tests were carried out at 500℃ to investigate its damage evolution. The accumulated plastic strain was selected to define the damage variable due to its clear physical meaning. A new fatigue-creep interaction damage model was proposed on the basis of continuum damage mechanics. A new equivalent impulse density for fatigue-creep tests was proposed to incorporate the holding time effect by transforming creep impulse density into fatigue impulse density. The experimental results indicated that the damage model is able to describe the damage evolution under these working conditions.展开更多
By using dropped stress creep method a new testing technique for measurement of the fa-tigue-creep interaction resistance is developed. At varied adjusted mean stresses the creep testingwas performed repeatedly When a...By using dropped stress creep method a new testing technique for measurement of the fa-tigue-creep interaction resistance is developed. At varied adjusted mean stresses the creep testingwas performed repeatedly When an unlimited extensive incubation period with zero creep rate oc-curred. the stress cavsing zero creep rate is defined as fatigue-creep resistance. The developped test-ing technique was used to measure the fatigue-creep resistance in F anc C regions. The dynamic ef-fective stress could yield a better descrption of fatigue and creep interaction. The fatigue-creep rateequations with varied exponents inF of C region are established. The different deformation mecha-nisms in F or C regions are indicated展开更多
文摘The cleavage rupture behaviour of the Ti alloy TC11 with various microstructures,i.e., equiaxed,duplex and interweaving,has been studied under fatigue-creep interaction at 520℃.It was found to be not only related to the rate of creep void initiating,but also control- led by the creep strain accumulation on holding under tension test and stress state at crack-tip.This seem to be combinably offected by both value of critic void initiating strain and parameter,V_(GC),of critic void growth.
文摘In Situ observation of deformation and fracture for superalloy GH169 under combined fatigue-creep action is made by using high temperature metalloscope,it is shown that under the test conditions the deformution takes place by merely of slipping,twinning and grain houndary sliding,and the mode of failure depends on the microstructure of specimen. lntergranular cracks arise.from W-type voids produced by the stress concentration at triple point which could not be relaxed by the interior deformation of grains and the local deformathm region along grain bounaries.And the crack propagation mechanism is the nucleation,growth and linkage of carities at the grain boundaries.Transgranular cracks form from deformatiom damages within the grain,and its propagation mechanism is shear rupture along the slip phme.
文摘AISI H13 （4Cr5MoSiV1） is one of the commonly used materials for extrusion tool, and it suffers from fatigue-creep damage during the hot extrusion process. Stress-controlled fatigue and creep-fatigue interaction tests were carried out at 500℃ to investigate its damage evolution. The accumulated plastic strain was selected to define the damage variable due to its clear physical meaning. A new fatigue-creep interaction damage model was proposed on the basis of continuum damage mechanics. A new equivalent impulse density for fatigue-creep tests was proposed to incorporate the holding time effect by transforming creep impulse density into fatigue impulse density. The experimental results indicated that the damage model is able to describe the damage evolution under these working conditions.
文摘By using dropped stress creep method a new testing technique for measurement of the fa-tigue-creep interaction resistance is developed. At varied adjusted mean stresses the creep testingwas performed repeatedly When an unlimited extensive incubation period with zero creep rate oc-curred. the stress cavsing zero creep rate is defined as fatigue-creep resistance. The developped test-ing technique was used to measure the fatigue-creep resistance in F anc C regions. The dynamic ef-fective stress could yield a better descrption of fatigue and creep interaction. The fatigue-creep rateequations with varied exponents inF of C region are established. The different deformation mecha-nisms in F or C regions are indicated
