The distributions of temperature and residual stresses in thin plates of BT20titanium alloy are numerically analyzed by three-dimensional finite element software duringelectron beam welding and electron beam local pos...The distributions of temperature and residual stresses in thin plates of BT20titanium alloy are numerically analyzed by three-dimensional finite element software duringelectron beam welding and electron beam local post-weld heat treatment (EBLPWHT). Combined withnumerical calculating results, the effects of different EBLPWHT mode and parameters, including heattreating position, heating width and heating time, on the distribution of welding residual stressesare analyzed. The results show that, the residual tensile stresses in weld center can be largelydecreased when the weld is heat treated at back preface of the plate. The numerical results alsoindicated that the magnitude of the residual longitudinal stresses of the weld and the zone vicinityof the weld is decreased, and the range of the residual longitudinal stresses is increased alongwith the increase of heating width and heating time.展开更多
The potential applications of some high tenologies in refractories,such as,nanotechnology,in-situ synthesis,self-propagating high-temperature synthesis,functional gradient materials,computer assisted design and some n...The potential applications of some high tenologies in refractories,such as,nanotechnology,in-situ synthesis,self-propagating high-temperature synthesis,functional gradient materials,computer assisted design and some new advanced refactories in Si-Al-O-N system are briefly described.The characteristics and preparation processes of these new refractories areintroduced,and the remaining problems awaiting effective solutions are pointed out .Some suggesions on future diection of research and development are fitly made.展开更多
People have many beliefs about the accuracy of language.But in fact, language is more often than not deceptive. In human language, many words with apparently precise meaning or definition often express uncertain conce...People have many beliefs about the accuracy of language.But in fact, language is more often than not deceptive. In human language, many words with apparently precise meaning or definition often express uncertain concept which suggests an inherent linguistic characteristic of language -- fuzziness.展开更多
基金This project is supported by Foundation of National Defense Technology Key Laboratory, China (No.99JS50.3.2JW1402).
文摘The distributions of temperature and residual stresses in thin plates of BT20titanium alloy are numerically analyzed by three-dimensional finite element software duringelectron beam welding and electron beam local post-weld heat treatment (EBLPWHT). Combined withnumerical calculating results, the effects of different EBLPWHT mode and parameters, including heattreating position, heating width and heating time, on the distribution of welding residual stressesare analyzed. The results show that, the residual tensile stresses in weld center can be largelydecreased when the weld is heat treated at back preface of the plate. The numerical results alsoindicated that the magnitude of the residual longitudinal stresses of the weld and the zone vicinityof the weld is decreased, and the range of the residual longitudinal stresses is increased alongwith the increase of heating width and heating time.
文摘The potential applications of some high tenologies in refractories,such as,nanotechnology,in-situ synthesis,self-propagating high-temperature synthesis,functional gradient materials,computer assisted design and some new advanced refactories in Si-Al-O-N system are briefly described.The characteristics and preparation processes of these new refractories areintroduced,and the remaining problems awaiting effective solutions are pointed out .Some suggesions on future diection of research and development are fitly made.
文摘People have many beliefs about the accuracy of language.But in fact, language is more often than not deceptive. In human language, many words with apparently precise meaning or definition often express uncertain concept which suggests an inherent linguistic characteristic of language -- fuzziness.
