In this paper,the interrupted and ruptured creep tests were carried out in a novel second generation single crystal superalloy named DD11 at 1100℃/130 MPa.The alloy exhibited typical creep curve including primary,ste...In this paper,the interrupted and ruptured creep tests were carried out in a novel second generation single crystal superalloy named DD11 at 1100℃/130 MPa.The alloy exhibited typical creep curve including primary,steady,and tertiary three creep stages.The microstructural evolution at different stages of the creep were analyzed by scanning electron microscopy(SEM)and transmission electron microscopy(TEM).The results show that theγ′phases transform into rafted structure at the early stage of the steady creep and keep stable during the steady creep stage.As the creep goes on,the rafted structure further coarsens and the topological inversion occurs.In addition,at the primary creep,the dislocations mainly move in theγmatrix and pile up in theγ/γ′interface since the matrix channels widen slightly.The formation of the regular interfacial dislocation networks occurs at the early stage of the steady creep.Under the low stress,the dominated deformation mechanism during steady creep stage is the climbing of the〈010〉type edge dislocation.Furthermore,the effect of the deformation mechanism on creep property was discussed in detail.展开更多
In order to clarify the recrystallization mechanism of low-densityδ-ferrite steel Fe-4AI-2Ni,interrupted and single-pass compression tests were carried out.In this regard,five deformation temperatures(750-950 at an i...In order to clarify the recrystallization mechanism of low-densityδ-ferrite steel Fe-4AI-2Ni,interrupted and single-pass compression tests were carried out.In this regard,five deformation temperatures(750-950 at an interval of 50°C)and different hold time were selected.It was observed that the softening and recrystallization fraction was enhaneed with increased deformation temperature and hold time.The original grain bounclaries were the preferred nucleation sites for recrystallized grains,and recrystallization had an impact on obtaining homogeneous and fine-grained structure.Recrystallization in the ferritic alloy commenced after a significant degree of softening,and the softening associated with recovery was appreciably less.The optimum rolling deformation temperature was identified to be greater than 900°C.展开更多
The static softening behavior of aluminum alloy A6082 was investigated by interrupted hot tests conducted on Gleeble-1500 simulator at deformation temperatures from 573 to 773 K and strain rates from 0.1 to 10 s-1,wit...The static softening behavior of aluminum alloy A6082 was investigated by interrupted hot tests conducted on Gleeble-1500 simulator at deformation temperatures from 573 to 773 K and strain rates from 0.1 to 10 s-1,with a pre-strain from 0.3 to 0.7 and variable inter-pass delay times.The offset method was applied to convert the changes in flow stress between two passes to static softening fraction.The microstructural changes were characterized by the quantitative metallography of quenched specimens.The results showed both static softening and static recrystallization curves exhibited a simple sigmoidal shape;the static softening is related to the static recrystallization in a nonlinear manner with 50% static recrystallized volume fraction corresponding to 80% static softening fraction;an increase in temperature,strain rate or pre-strain yields a decrease in the time for 50% static recrysallized volume fraction,on which the temperature has the most remarkable influence;Si and Mn additions accelerate the process of static recrystallization.Finally,the equations of static recrystallization kinetics of this alloy were developed with a good agreement between the predicted and experimental results.展开更多
目的比较腹腔镜下T管缝合时预置缝线法与传统缝合方法的效果差异。方法回顾性分析2020年6月至2023年9月间空军特色医学中心行腹腔镜T管缝合的患者的临床资料,对照组采用传统的T管缝合方法,研究组采用预置缝线的T管缝合方法:间断缝合,进...目的比较腹腔镜下T管缝合时预置缝线法与传统缝合方法的效果差异。方法回顾性分析2020年6月至2023年9月间空军特色医学中心行腹腔镜T管缝合的患者的临床资料,对照组采用传统的T管缝合方法,研究组采用预置缝线的T管缝合方法:间断缝合,进针和出针时前一针的缝线不打紧,每组24例。比较两组患者T管缝合时间和注水试验阳性率。结果研究组术中T管缝合时间少于对照组[(12.61±0.88)min vs(17.62±0.58)min,t=-23.34,P<0.001],注水试验阳性率低于对照组[0 vs 25%(6/24),P=0.029],差异均有统计学意义。结论应用预置缝线的间断缝合法可提高腹腔镜下T管缝合速度,使缝合更确切,较传统方法有明显优势。展开更多
The physics phenomena of copper and stainless steel in the process of forming friction welding joint are recorded and observed by the interrupted test method.The test shows that the butt friction welding process of co...The physics phenomena of copper and stainless steel in the process of forming friction welding joint are recorded and observed by the interrupted test method.The test shows that the butt friction welding process of copper and stainless steel bar can be divided into three stages approximately: the adhesion at the beginning friction stage, the friction inside the copper and the plastic ring expansion, and the friction on the bound surface of copper-stainless steel and in stainless steel. During the process,the friction surface was transformed twice.展开更多
基金This study was financially supported by the National Natural Science Foundation of China(No.51471014).
文摘In this paper,the interrupted and ruptured creep tests were carried out in a novel second generation single crystal superalloy named DD11 at 1100℃/130 MPa.The alloy exhibited typical creep curve including primary,steady,and tertiary three creep stages.The microstructural evolution at different stages of the creep were analyzed by scanning electron microscopy(SEM)and transmission electron microscopy(TEM).The results show that theγ′phases transform into rafted structure at the early stage of the steady creep and keep stable during the steady creep stage.As the creep goes on,the rafted structure further coarsens and the topological inversion occurs.In addition,at the primary creep,the dislocations mainly move in theγmatrix and pile up in theγ/γ′interface since the matrix channels widen slightly.The formation of the regular interfacial dislocation networks occurs at the early stage of the steady creep.Under the low stress,the dominated deformation mechanism during steady creep stage is the climbing of the〈010〉type edge dislocation.Furthermore,the effect of the deformation mechanism on creep property was discussed in detail.
文摘In order to clarify the recrystallization mechanism of low-densityδ-ferrite steel Fe-4AI-2Ni,interrupted and single-pass compression tests were carried out.In this regard,five deformation temperatures(750-950 at an interval of 50°C)and different hold time were selected.It was observed that the softening and recrystallization fraction was enhaneed with increased deformation temperature and hold time.The original grain bounclaries were the preferred nucleation sites for recrystallized grains,and recrystallization had an impact on obtaining homogeneous and fine-grained structure.Recrystallization in the ferritic alloy commenced after a significant degree of softening,and the softening associated with recovery was appreciably less.The optimum rolling deformation temperature was identified to be greater than 900°C.
基金the National Natural Science Foundation of China (No. 50675133)the National Basic Research Program (973) of China (No. 2006CB705401)
文摘The static softening behavior of aluminum alloy A6082 was investigated by interrupted hot tests conducted on Gleeble-1500 simulator at deformation temperatures from 573 to 773 K and strain rates from 0.1 to 10 s-1,with a pre-strain from 0.3 to 0.7 and variable inter-pass delay times.The offset method was applied to convert the changes in flow stress between two passes to static softening fraction.The microstructural changes were characterized by the quantitative metallography of quenched specimens.The results showed both static softening and static recrystallization curves exhibited a simple sigmoidal shape;the static softening is related to the static recrystallization in a nonlinear manner with 50% static recrystallized volume fraction corresponding to 80% static softening fraction;an increase in temperature,strain rate or pre-strain yields a decrease in the time for 50% static recrysallized volume fraction,on which the temperature has the most remarkable influence;Si and Mn additions accelerate the process of static recrystallization.Finally,the equations of static recrystallization kinetics of this alloy were developed with a good agreement between the predicted and experimental results.
文摘目的比较腹腔镜下T管缝合时预置缝线法与传统缝合方法的效果差异。方法回顾性分析2020年6月至2023年9月间空军特色医学中心行腹腔镜T管缝合的患者的临床资料,对照组采用传统的T管缝合方法,研究组采用预置缝线的T管缝合方法:间断缝合,进针和出针时前一针的缝线不打紧,每组24例。比较两组患者T管缝合时间和注水试验阳性率。结果研究组术中T管缝合时间少于对照组[(12.61±0.88)min vs(17.62±0.58)min,t=-23.34,P<0.001],注水试验阳性率低于对照组[0 vs 25%(6/24),P=0.029],差异均有统计学意义。结论应用预置缝线的间断缝合法可提高腹腔镜下T管缝合速度,使缝合更确切,较传统方法有明显优势。
文摘The physics phenomena of copper and stainless steel in the process of forming friction welding joint are recorded and observed by the interrupted test method.The test shows that the butt friction welding process of copper and stainless steel bar can be divided into three stages approximately: the adhesion at the beginning friction stage, the friction inside the copper and the plastic ring expansion, and the friction on the bound surface of copper-stainless steel and in stainless steel. During the process,the friction surface was transformed twice.
