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991.
采用镶嵌异种材料作为标识材料的方法,用不同搅拌针形状的搅拌头,进行了搅拌摩擦焊试验.结果表明,搅拌针形状影响焊缝塑化金属流动的行为,导致焊缝截面形貌发生变化.搅拌针表面的反螺纹使搅拌针周围塑化金属向下流动,迫使搅拌针端部周边金属向上运动,焊核中心处于焊缝横截面下部;正螺纹使搅拌针周围塑化金属向上流动,迫使轴肩下方及周边金属向下运动,焊核中心处于焊缝横截面上部.改变搅拌针形状及长度,可以改变搅拌针下方及附近区域塑化金属的流动形态,从而改变焊缝底部的成形及包铝层进入焊缝的深度. 相似文献
992.
利用x射线衍射(XRD)和差示扫描量热法(DSC)研究了轧制对Zr65Al7.5Ni10Cu12.5Ag5非晶合金中二十面体准晶相析出的影响.实验发现,经轧制塑性变形合金在随后的加热过程中二十面体准晶相的析出量增加,在变形量ε=70%时达到最大.另外,析出的二十面体准晶相的稳定性随着变形量增大而提高,在ε=70%时达到最大,随后又开始降低.这是由于合金在塑性变形过程中的原子组态发生变化所致. 相似文献
993.
Hualong Li Emilie Hsu Jerzy Szpunar Ravi Verma Jon. T. Carter 《Journal of Materials Engineering and Performance》2007,16(3):321-326
In order to determine the deformation modes in AZ31 magnesium alloy at room temperature, computer simulations of deformation
texture development and calculation of formability have been carried out. The simulation results were compared with the measured
texture results. Based on agreement between the experiments and simulations the active deformation modes were determined.
A Visco Plastic Self Consistent model was employed for the simulation of plastic deformation. Simulations and experiments
were performed for different initial textures. The goal of the study was to develop the understanding of deformation texture
evolution and its effects on mechanical properties of magnesium, with an ultimate goal of improving room temperature formability
of magnesium alloys.
This article was presented at Materials Science & Technology 2006, Innovations in Metal Forming symposium held in Cincinnati,
OH, October 15-19, 2006. 相似文献
994.
J.S. Huo J.T. Gou L.Z. Zhou X.Z. Qin G.S. Li 《Journal of Materials Engineering and Performance》2007,16(1):55-62
Creep properties of the experimental superalloy were investigated in the temperature range 1073–1223 K and stress range 110–550 MPa.
The observations of dislocation structures during different creep conditions reveal that in the high stress region, particle-shearing
mechanisms including stacking fault formation and antiphase boundary creation are operative and in the low stress region,
the dislocation climb mechanism is dominant. From the plot of minimum creep rate versus applied stress, a very low stress
region with exponent n < 2, which is related to diffusional creep, is found. Based on the experimental results, a stress–temperature creep deformation
mechanism map for the alloy is constructed. On the basis of particle hardening theories and various dislocation-creep theories,
the dislocation-creep transitions in terms of internal stress are discussed and calculated threshold stresses of various creep
deformation mechanisms indicates that the particle shearing is easier to operate than Orowan looping at high stresses, and
general climb is easy to happen at low stresses. 相似文献
995.
996.
997.
1.Illtroduct!onWhilst the metallurgy of*theurgy warm rolling ofIF steel In the ferrlte region has beenextensively studied 11,2],that ofcold rolling has not received the same amouM ofattentlon.This is probably because there has been less cold rolling tec… 相似文献
998.
Laser additive manufacturing technology with powder feeding was employed to repair wrought Ti17 titanium alloy with small surface defects. The microstructure, micro-hardness and room temperature tensile properties of laser additive repaired (LARed) specimen were investigated. The results show that, cellular substructures are observed in the laser deposited zone (LDZ), rather than the typical α laths morphology due to lack of enough subsequent thermal cycles. The cellular substructures lead to lower micro-hardness in the LDZ compared with the wrought substrate zone which consists of duplex microstructure. The tensile test results indicate that the tensile deformation process of the LARed specimen exhibits a characteristic of dramatic plastic strain heterogeneity and fracture in the laser repaired zone with a mixed dimple and cleavage mode. The tensile strength of the LARed specimen is slightly higher than that of the wrought specimen and the elongation of 11.7% is lower. 相似文献
999.
The hot deformation behavior of Fe–26 Mn–6.2 Al–0.05 C steel was studied by experimental hot compression tests in the temperature range of 800–1050 °C and strain rate range of 0.01–30 s21 on a Gleeble-3500 thermal simulation machine. The microstructural evolution during the corresponding thermal process was observed in situ by confocal laser scanning microscopy. Electron backscattered diffraction and transmission electron microscopy analyses were carried out to observe the microstructural morphology before and after the hot deformation. Furthermore, interrupted compression tests were conducted to correlate the microstructural characteristics and softening mechanisms at different deformation stages.The results showed that hot compression tests of this steel were all carried out on a duplex matrix composed of austenite and d-ferrite. As the deformation temperature increased from 800 to 1050 °C, the volume fraction of austenite decreased from 70.9% to 44.0%, while that of d-ferrite increased from 29.1% to 56.0%. Due to the different stress exponents(n) and apparent activation energies(Q), the generated strain was mostly accommodated by d-ferrite at the commencement of deformation, and then both dynamic recovery and dynamic recrystallization occurred earlier in d-ferrite than in austenite.This interaction of strain partitioning and unsynchronized softening behavior caused an abnormal hot deformation behavior profile in the Fe–Mn–Al duplex steel, such as yield-like behavior, peculiar work-hardening behavior, and dynamic softening behavior, which are influenced by not only temperature and strain rate but also by microstructural evolution. 相似文献
1000.