scholarly journals The mechanical properties of high strength Al alloy sheet under quasi-static-dynamic loading

Author(s):  
L L Xia ◽  
Y Xu ◽  
S H Zhang ◽  
H W Song ◽  
D Y Chen
2009 ◽  
Vol 23 (06n07) ◽  
pp. 843-848 ◽  
Author(s):  
BONG-JAE CHOI ◽  
KYUNG-EUI HONG ◽  
YOUNG-JIG KIM

The aim of this research is to develop the high strength Al alloy sheet for the automotive body. For the fabrication Al - Mg alloy sheet, the composition of alloying elements was designed by the properties database and CALPHAD (Calculation Phase Diagram) approach which can predict the phases during solidification using thermodynamic database. Al - Mg alloys were designed using CALPHAD approach according to the high content of Mg with minor alloying elements. After phase predictions by CALPHAD, designed Al - Mg alloys were manufactured. Addition of Mg in Al melts were protected by dry air/Sulphur hexafluoride (SF6) mixture gas which can control the severe Mg ignition and oxidation. After rolling procedure of manufactured Al - Mg alloys, mechanical properties were examined with the variation of the heat treatment conditions.


2018 ◽  
Vol 2018 ◽  
pp. 1-12 ◽  
Author(s):  
Hui Chen ◽  
Jinjin Zhang ◽  
Jin Yang ◽  
Feilong Ye

The tensile behaviors of corroded steel bars are important in the capacity evaluation of corroded reinforced concrete structures. The present paper studies the mechanical behavior of the corroded high strength reinforcing steel bars under static and dynamic loading. High strength reinforcing steel bars were corroded by using accelerated corrosion methods and the tensile tests were carried out under different strain rates. The results showed that the mechanical properties of corroded high strength steel bars were strain rate dependent, and the strain rate effect decreased with the increase of corrosion degree. The decreased nominal yield and ultimate strengths were mainly caused by the reduction of cross-sectional areas, and the decreased ultimate deformation and the shortened yield plateau resulted from the intensified stress concentration at the nonuniform reduction. Based on the test results, reduction factors were proposed to relate the tensile behaviors with the corrosion degree and strain rate for corroded bars. A modified Johnson-Cook strength model of corroded high strength steel bars under dynamic loading was proposed by taking into account the influence of corrosion degree. Comparison between the model and test results showed that proposed model properly describes the dynamic response of the corroded high strength rebars.


2017 ◽  
Vol 898 ◽  
pp. 179-190 ◽  
Author(s):  
Jin Rong Zuo ◽  
Long Gang Hou ◽  
Jin Tao Shi ◽  
Hua Cui ◽  
Lin Zhong Zhuang ◽  
...  

A final thermomechanical treatment (FTMT) including peak aging and subsequent dynamic aging was proposed to prepare 7055 Al alloy sheets. The optimization was based on nine well-planned orthogonal experiments. Three main processing conditions in the thermomechanical treatment for obtaining the optimum synthetic properties of 7055 (i.e. preheating temperature, final rolling temperature and deformation degree) were investigated. It was shown that the final rolling temperature is the most important factor among the three parameters, and the optimum properties (yield strength: 651 MPa, ultimate tensile strength: 660 MPa) of 7055 Al alloy sheet can be gained with preheating at 140oC and 40% deformation at 170oC. With dynamic aging, grain boundary precipitates became discontinuous without much coarsening of matrix precipitates, while they were continuously distributed after T6 aging. The present optimal FTMT process can improve the intergranular / exfoliation corrosion resistance without sacrificing the strength compared to T6 tempering. The present FTMT process as a good alternative can produce high-strength Al alloy sheets with high strength and good corrosion resistance efficiently and economically.


2007 ◽  
Vol 124-126 ◽  
pp. 1397-1400 ◽  
Author(s):  
Byoung Soo Lee ◽  
Hoon Cho

The microstructures and mechanical properties of unidirectional deformation structured Al alloy during ECAP with various deformation routes were investigated. In order to fabricate unidirectional deformation structure for Al alloy, hot extrusion was carried out. It was found that the deformation route A in ECAP routes is the dominant route for the grain refinement and strengthening. In deformation route A, the high strength ultra-fine grained Al alloy with a grain size of ~ 200 nm was obtained due to the accumulation of consecutive strain process. In contrast, the strength of ECAP’ed Al alloy produced via deformation route C was greatly increased after one pass because the grains were strained and cancelled each pass. By contrast, the equiaxed grains were obtained in deformation route BC because the sample was rotated 90 O in the same sense in each pass. The deformation route BC was superior to the deformation route C because the deformation route BC was more favorable than the deformation route C in the accumulation of consecutive strain. It is also found that unidirectional deformation structured Al alloy via hot extrusion shows similar grain refinement tendency with equiaxed structured Al alloy during ECAP processing.


2012 ◽  
Vol 452-453 ◽  
pp. 81-85 ◽  
Author(s):  
Ming He Chen ◽  
Y.Y. Cao ◽  
W. Chen ◽  
Guo Liang Chen

In order to improve formability of high strength Al-alloy sheet metal, in this paper, it come up with the synchronized cooling hot forming process. Taking the aluminum alloy of 6016 H18 aluminum alloy, which carried out its technology test by Gleeble3500 hot-mechanical simulator. The process parameters such as deformation temperature T, holding time t and cooling rate v is investigated by the orthogonal test and the microstructure is analyzed simultaneously. The results show that the synchronized cooling hot forming process can be applied to 6016 H18 aluminum alloy, it both improves the formability of 6016 H18 aluminum alloy significantly and obtains the high strength after forming, it can meet the purpose of implementing deformation and enhanced in one process step, the proper combination of process parameters are T=450 °C, t=210 s, v=60 °C/s. Strengthening mechanism is which there is a large number of strengthening phase precipitated from matrix in technology process, the strengthening phases are coarser and the dispersed uniformity is a bit worse compared with that of T4 state.


2008 ◽  
Vol 22 (31n32) ◽  
pp. 5895-5900 ◽  
Author(s):  
INSOO KIM ◽  
SAIDMUROD AKRAMOV ◽  
HAE BONG JEONG

The physical, mechanical properties and formability of sheet metal depend on preferred crystallographic orientations (texture). In this research work, we investigated texture development and formability of AA 3003 aluminum alloy sheets after asymmetry rolling and subsequent heat treatment. After asymmetry rolling, the specimens showed fine grain size. We also investigated the change of the plastic strain ratios after asymmetry rolling and subsequent heat-treating condition. The plastic strain ratios of asymmetrically rolled and subsequent heat treated samples are 1.5 times higher than the initial AA 3003 Al alloy sheets. These could be attributed to the formation of ND//<111> texture component through asymmetry rolling in Al sheet.


2006 ◽  
Vol 15-17 ◽  
pp. 345-350 ◽  
Author(s):  
Chang Yong Lee ◽  
Won Bae Lee ◽  
Yun Mo Yeon ◽  
Keun Song ◽  
Jeong Hoon Moon ◽  
...  

The microstructure and mechanical properties of spot friction stir welded A 5052 alloy were investigated with insertion depth of welding tool. As the insertion depth of welding tool increased, the size of stirring zone increased and the thickness of upper sheet decreased. The value of shear load was the lowest at the shallowest insertion depth and increased to the highest value of 3.35 kN at a 1.6mm of insertion depth. An increase in the pin insertion depth beyond 1.6mm did not result in further increase in the lap shear load. Spot friction stir welded joints showed shear fracture mode at shallower insertion depths and fracture mode changed to plug fracture mode as the insertion depth was deeper.


2009 ◽  
Vol 67 ◽  
pp. 53-58
Author(s):  
V. Anil Kumar ◽  
M.K. Karthikeyan ◽  
Rohit Kumar Gupta ◽  
P. Ramkumar ◽  
P.P. Sinha

Severe plastic deformation processes (SPD) are gaining importance as advanced materials processing techniques and hold immense potential in obtaining ultra fine-grained high strength materials. Among the SPD techniques, Equal channel angular pressing (ECAP) has its own merits to produce materials with ultra fine grains in bulk with better mechanical properties. The material deforms with high level of plastic strain inside the channel resulting in grain refinement of the output material with improvement in mechanical properties. A very viable die configuration was conceptualized and die was made with 1200 channel angle. Processing of 25 mm dia. of Al alloy AA2219 at room temperature was successfully carried out and grain refinement was observed. The mechanism of grain refinement has been studied using optical and transmission electron microscopy (TEM). It was observed that low energy dislocation structure (LEDS) forms concurrently with sub-grain structure due to dislocation rearrangements, which provide stability to the evolving sub-grain structure. Dislocation mobility is hindered by the presence of precipitates and / or intermetallic dispersoids present in the matrix and results in presence of dislocations in grain interiors. The pile up of dislocations at intermetallic dispersoids was confirmed from the dark field TEM micrographs. Present paper describes the experimental procedure and followed to attain severe plastic deformation through ECAP. Increase in hardness as well as refinement in the grain size after 5-passes have been discussed in light of extensive optical and TEM. The mechanisms of grain refinement to achieve nano-grained structure and strengthening accrued from the grain refinement through ECAP has been discussed.


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