The influence of aging time,measuring frequency and strain amplitude on the internal friction of TiNi51/TiNi50.2 sandwich composite was investigated.The DSC and internal friction measurements were employed to characte...The influence of aging time,measuring frequency and strain amplitude on the internal friction of TiNi51/TiNi50.2 sandwich composite was investigated.The DSC and internal friction measurements were employed to characterize the sample.The two internal friction peaks of the specimen were confirmed corresponding to the reverse transformation of TiNi51 and TiNi50.2 component, respectively.The internal friction as a function of the temperature at different measuring frequencies was presented and it was found that the height of both internal friction peaks increased with decreasing frequency;however,the increase corresponding to TiNi50.2 component was larger than that of TiNi51 component.Furthermore,the internal friction of the TiNi/TiNi composite alloy decreased with increasing the measuring strain amplitude.The height of internal friction peak of TiNi51 component increased with increasing the aging time,whereas that of the TiNi50.2 component did not change significantly.The increase in internal friction of TiNi51 appeared to be associated with the formation and growth of precipitate during the aging process.展开更多
To solve the difficulty in the explosive welding of corrosion-resistant aluminum and stainless steel tubes, three technologies were proposed after investigating the forming mechanism through experiments. Then, a 3D fi...To solve the difficulty in the explosive welding of corrosion-resistant aluminum and stainless steel tubes, three technologies were proposed after investigating the forming mechanism through experiments. Then, a 3D finite element model was established for systematic simulations in the parameter determination. The results show that the transition-layer approach, the coaxial initial assembly of tubes with the top-center-point the detonation, and the systematic study by numerical modeling are the key technologies to make the explosive welding of LF6 aluminum alloy and 1Cr18Ni9Ti stainless steel tubes feasible. Numerical simulation shows that radial contraction and slope collision through continuous local plastic deformation are necessary for the good bonding of tubes. Stand-off distances between tubes （D1 and D2） and explosives amount （R） have effect on the plastic deformation, moving velocity, and bonding of tubes. D1 of 1 mm, D2 of 2 mm, and R of 2/3 are suitable for the explosive welding of LF6-L2-1Cr18Ni9Ti three-layer tubes. The plastic strain and moving velocity of the flyer tubes in-crease with the increase of stand-off distance. More explosives （R2/3） result in the asymmetrical distribution of plastic strain and non-bonding at the end of detonation on the tubes.展开更多
Interfacial structure greatly affects the mechanical properties of laminated plates.However,the critical material properties that impact the interfacial morphology,appearance,and associated bonding mechanism of explos...Interfacial structure greatly affects the mechanical properties of laminated plates.However,the critical material properties that impact the interfacial morphology,appearance,and associated bonding mechanism of explosive welded plates are still unknown.In this paper,the same base plate(AZ31B alloy)and different flyer metals(aluminum alloy,copper,and stainless steel)were used to investigate interfacial morphology and structure.SEM and TEM results showed that typical sine wave,wave-like,and half-wave-like interfaces were found at the bonding interfaces of Al/Mg,Cu/Mg and SS/Mg clad plates,respectively.The different interfacial morphologies were mainly due to the differences in hardness and yield strength between the flyer and base metals.The results of the microstructural distribution at the bonding interface indicated metallurgical bonding,instead of the commonly believed solid-state bonding,in the explosive welded clad plate.In addition,the shear strength of the bonding interface of the explosive welded Al/Mg,Cu/Mg and SS/Mg clad plates can reach up to 201.2 MPa,147.8 MPa,and 128.4 MPa,respectively.The proposed research provides the design basis for laminated composite metal plates fabrication by explosive welding technology.展开更多
The study is a first attempt to prepare bulk NiTi/NiTi shape memory alloy （SMA） laminates with a macroscopic heterogeneous composition by explosive welding and investigate their microstructures and martensitic trans...The study is a first attempt to prepare bulk NiTi/NiTi shape memory alloy （SMA） laminates with a macroscopic heterogeneous composition by explosive welding and investigate their microstructures and martensitic transformation behaviors. After explosive weld- ing, a perfect interfacial bonding between the two components and a reversible martensitic transformation are realized in the tandem. Results show achievement of a fine granular structure and the maximum value of microhardness near the welding interface because of the excessive cold plastic deformation and the high impact velocity during the explosive welding. Meanwhile, the effects of aging on the transformation of the welded tandem are investigated by differential scanning calorimeter （DSC） and subject to discussion. The trans- formation temperatures of NiTi/NiTi SMAs increase with the rise of the aging temperature. The experimental results indicate the shape memory properties of NiTi/NiTi SMA fabricated by explosive welding can be improved by optimizing the aging technology.展开更多
基金Projects(5087112150671120)supported by the National Natural Science Foundation of China
文摘The influence of aging time,measuring frequency and strain amplitude on the internal friction of TiNi51/TiNi50.2 sandwich composite was investigated.The DSC and internal friction measurements were employed to characterize the sample.The two internal friction peaks of the specimen were confirmed corresponding to the reverse transformation of TiNi51 and TiNi50.2 component, respectively.The internal friction as a function of the temperature at different measuring frequencies was presented and it was found that the height of both internal friction peaks increased with decreasing frequency;however,the increase corresponding to TiNi50.2 component was larger than that of TiNi51 component.Furthermore,the internal friction of the TiNi/TiNi composite alloy decreased with increasing the measuring strain amplitude.The height of internal friction peak of TiNi51 component increased with increasing the aging time,whereas that of the TiNi50.2 component did not change significantly.The increase in internal friction of TiNi51 appeared to be associated with the formation and growth of precipitate during the aging process.
文摘To solve the difficulty in the explosive welding of corrosion-resistant aluminum and stainless steel tubes, three technologies were proposed after investigating the forming mechanism through experiments. Then, a 3D finite element model was established for systematic simulations in the parameter determination. The results show that the transition-layer approach, the coaxial initial assembly of tubes with the top-center-point the detonation, and the systematic study by numerical modeling are the key technologies to make the explosive welding of LF6 aluminum alloy and 1Cr18Ni9Ti stainless steel tubes feasible. Numerical simulation shows that radial contraction and slope collision through continuous local plastic deformation are necessary for the good bonding of tubes. Stand-off distances between tubes （D1 and D2） and explosives amount （R） have effect on the plastic deformation, moving velocity, and bonding of tubes. D1 of 1 mm, D2 of 2 mm, and R of 2/3 are suitable for the explosive welding of LF6-L2-1Cr18Ni9Ti three-layer tubes. The plastic strain and moving velocity of the flyer tubes in-crease with the increase of stand-off distance. More explosives （R2/3） result in the asymmetrical distribution of plastic strain and non-bonding at the end of detonation on the tubes.
基金Supported by National Natural Science Foundation of China(Grant Nos.51805359,51904206,51375328)Major program of national natural science foundation of China(U1710254),China Postdoctoral Science Foundation(Grant No.2018M631772)+2 种基金Shanxi Provincial Natural Science Foundation of China(Grant No.201901D211015)Scientific and Technological Innovation Programs of Higher Education Institutions in Shanxi Province(STIP)(Grant No.2019L0333)Central Special Fund for Guiding Local Science and Technology Development(YDZX20191400002149).
文摘Interfacial structure greatly affects the mechanical properties of laminated plates.However,the critical material properties that impact the interfacial morphology,appearance,and associated bonding mechanism of explosive welded plates are still unknown.In this paper,the same base plate(AZ31B alloy)and different flyer metals(aluminum alloy,copper,and stainless steel)were used to investigate interfacial morphology and structure.SEM and TEM results showed that typical sine wave,wave-like,and half-wave-like interfaces were found at the bonding interfaces of Al/Mg,Cu/Mg and SS/Mg clad plates,respectively.The different interfacial morphologies were mainly due to the differences in hardness and yield strength between the flyer and base metals.The results of the microstructural distribution at the bonding interface indicated metallurgical bonding,instead of the commonly believed solid-state bonding,in the explosive welded clad plate.In addition,the shear strength of the bonding interface of the explosive welded Al/Mg,Cu/Mg and SS/Mg clad plates can reach up to 201.2 MPa,147.8 MPa,and 128.4 MPa,respectively.The proposed research provides the design basis for laminated composite metal plates fabrication by explosive welding technology.
基金National Natural Science Foundation of China (50471021)
文摘The study is a first attempt to prepare bulk NiTi/NiTi shape memory alloy （SMA） laminates with a macroscopic heterogeneous composition by explosive welding and investigate their microstructures and martensitic transformation behaviors. After explosive weld- ing, a perfect interfacial bonding between the two components and a reversible martensitic transformation are realized in the tandem. Results show achievement of a fine granular structure and the maximum value of microhardness near the welding interface because of the excessive cold plastic deformation and the high impact velocity during the explosive welding. Meanwhile, the effects of aging on the transformation of the welded tandem are investigated by differential scanning calorimeter （DSC） and subject to discussion. The trans- formation temperatures of NiTi/NiTi SMAs increase with the rise of the aging temperature. The experimental results indicate the shape memory properties of NiTi/NiTi SMA fabricated by explosive welding can be improved by optimizing the aging technology.
