ZH Tu
,
Z Zhang
,
L.Z. Zhaoand T.X. Mao (Cryogenic Laboratory
,
Chinese Academy of Sciences
,
Beijing 100080
,
China) (Institute of Mechanics
,
Chinese Academy of Sciences
,
Beijing 100080
,
China )
金属学报(英文版)
The mechanical properties of a type of Al-alloy weld including strength, fracture tough-ness and ductility were comprehensively studied at different temperatures. The frac-ture behavior and weld micro features were also characterized. The surface crack test method was adopted to study the fracture toughness and a multiple specimen test ap-paratus was designed to perform the cryogenic experiments. The relationship between the mechanical properties and temperature was obtained together with the fracture toughness distribution in the weld.
关键词:
Al-alloy weld
,
null
,
null
,
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Z Zhang
,
ZH Tu
,
L.F. Li
,
L.Z. Zhaoand D. Jin (Cryogenic Laboratory Chinese Acaderw of Sciences
,
Beijing 100080
,
China )H.J Lu (Beijing Institute of Aerospace Materials and Technology
,
Beijing 100076
,
China)
金属学报(英文版)
Low temperature may greatly affect the mechanical properties of materials. Some in-teresting mechanical phenomena were detected at very low temperature. In this study,a multi-sample tensile installation was designed to study the plastic deformation be-havior for Ti-5Al-2.5Sn extra-low-interstitial (ELI) alloy at liquid helium temperature.The special geometrical instability phenomena in low temperature, serrated deforma-tion and multi necking, was studied in detail in this project. Slip and twinning were determined in the process of plastic fiow by SEM/TEM analysis. Efficts of temper-ature and sequential straining on load drops in tensile stress-strain curves were also studied. Optical measurement method was used to gauge the geometrical characteristic of multi-necking specimens. The sensitivity of partial thermoplastic deformation and the equivalency of low tempemture with high velocity of this material were studied by using micro-mechanics analysis.The criterion of geometrical instability has been discussed. A computer simulation of the low temperature instability of plastic fiow in Ti-5Al-2.5Sn ELI alloy has been carried out. A computer model has been established which links the hot dtffusion and the plastic fiow of hcp alloys under assumption that the tempemture is homogeneous within the specimen and that the heat exchange with the thermal bath is the control-ling step in the heat release. The computer simulation of the deformation curves as a function of several mechanincal, geometrical and thermal parameters provides a re-alistic description of the experiments. The experimental data available are discnssed in the light of the computer simulation model.
关键词:
mechanical property
,
null
,
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