Effect of Aging Precipitates on the Bendability of an Al-Mg-Si Alloy

2014 ◽  
Vol 794-796 ◽  
pp. 572-577 ◽  
Author(s):  
Hidetaka Nakanishi ◽  
Mineo Asano ◽  
Hideo Yoshida
Keyword(s):  
Shear Bands ◽  
Natural Aging ◽  
Bending Test ◽  
Heat Radiation ◽  
Plate Material ◽  
Bake Hardening ◽  
Β Phase ◽  
Phase Precipitate ◽  
Aging Conditions ◽  
Better Than

Al-Mg-Si alloys are usually applied a T4 temper as the plate material for automobile bodies due to the necessity of a high bake hardening property. Many reports about the improvement in the bendability of Al-Mg-Si alloys applied a T4 temper have been published, because they easily crack during the hemming process. On the other hand, Al-Mg-Si alloys applied T6 and T7 tempers are used as the material of wiring plates and heat radiation devices. A high electrical conductivity and good bendability are necessary for these devices. In this study, the effect of the aging conditions on the bendability was investigated. As a result, the bendability at the T6 temper significantly decreased. The bendability under the aging temper, and over the aging temper was better than that at the T6 temper. Samples treated by natural-aging at high temperature before the T6 temper easily cracked during the bending test. It was postulated that the formation of shear bands was significant and the bendability decreased during the bending test under the high density and fine β phase precipitate conditions.

Effects of Isothermal Aging on Clustering and Paint-Bake Hardening Behavior in an Al-Mg-Si Alloy

2014 ◽  
Vol 794-796 ◽  
pp. 897-902 ◽  
Author(s):  
Yasuhiro Aruga ◽  
Masaya Kozuka ◽  
Yasuo Takaki ◽  
Tatsuo Sato
Keyword(s):  
Early Stage ◽  
Natural Aging ◽  
Atom Probe ◽  
Bake Hardening ◽  
Subsequent Aging ◽  
Significant Drop ◽  
Β Phase ◽  
Long Time ◽  
Hardness Increase ◽  
Small Clusters

The relationship between the cluster morphology formed during natural or artificial aging and the paint-bake hardening response in an Al-0.62Mg-0.93Si (mass%) alloy have been investigated using atom probe tomography (APT). Increasing the subsequent aging time at 170 °C causes a gradual increase in hardness in the artificially aged materials, while the retardation period of the hardness increase appears in the naturally aged materials at the early stage of aging. The statistically-proved records in the APT analysis have shown that the artificially aged materials have some large clusters. It is revealed that the hardening at the early stage of the subsequent aging at 170 °C is not promoted in the long-time naturally aged material although the number density of small clusters increases approximately 1.3 times by prolonged natural aging.Hence, we believe that the small clusters are hard to transform continuously into the β'' phase during aging at 170 °C. As for the naturally aged materials, the long-time aging leads to a significant drop in hardness at the early stage of aging at 170 °C. It is speculated that the Mg-Si mixed clusters formed after long-time natural aging can be reversed during the subsequent heat treatment.

Effects of Pre-Aging and Natural Aging on Bake Hardening Behavior in Al-Mg-Si Alloys

2014 ◽  
Vol 794-796 ◽  
pp. 1026-1031 ◽  
Author(s):  
Yasuo Takaki ◽  
Yasuhiro Aruga ◽  
Masaya Kozuka ◽  
Tatsuo Sato
Keyword(s):  
Aging Time ◽  
Early Stage ◽  
Natural Aging ◽  
Hardness Test ◽  
Age Hardening ◽  
Bake Hardening ◽  
Scanning Calorimetry ◽  
Hardening Behavior ◽  
Β Phase ◽  
Cluster 2

The effects of pre-aging and natural aging on the bake hardening behavior of Al-0.62Mg-0.93Si (mass%) alloy with multi-step aging process were investigated by means of Vickers hardness test, tensile test, differential scanning calorimetry analysis (DSC) and transmission electron microscopy (TEM). The characteristics of nanoclusters (nano scale solute atom clusters) formed during pre-aging and natural aging were also investigated using the three dimensional atom probe (3DAP) analysis. The results revealed the occurrence of natural age hardening and that the bake hardening response was decreased after the extended natural aging even though the pre-aging was conducted before natural aging. Since the 3DAP results exhibited the Si-rich clusters were newly formed during extended natural aging, it was assumed that the Si-rich clusters caused the natural age hardening and the reduced bake hardening response corresponding to Cluster(1). The decrease of the bake hardening response was markedly higher in the later stage of bake hardening than in the early stage. The size of the β’’ precipitates were reduced with increasing the natural aging time. Exothermic peaks of Peak 2 and Peak 2’ were observed in the DSC curves for the alloys pre-aged at 363K. Peak 2’ became larger with the natural aging time. This is well understood by the following model. The transition from Cluster(2) to the β’’ phase occurs preferentially at the early stage of the bake hardening. Then the growth of the β’’ phase is inhibited by the presence of Cluster(1) at the later stage of bake hardening. The combined formation of Cluster(1) and Cluster(2) by the multi-step aging essentially affects the bake hardening response and the β’’ precipitates in the Al-Mg-Si alloys.

scholarly journals Effect of High Strain Rate on Adiabatic Shearing of α+β Dual-Phase Ti Alloy

Materials ◽  
2021 ◽  
Vol 14 (8) ◽  
pp. 2044
Author(s):  
Fang Hao ◽  
Yuxuan Du ◽  
Peixuan Li ◽  
Youchuan Mao ◽  
Deye Lin ◽  
...  
Keyword(s):  
Strain Rate ◽  
Split Hopkinson Pressure Bar ◽  
Damage Tolerance ◽  
Shear Bands ◽  
Dual Phase ◽  
Ti Alloy ◽  
Hopkinson Pressure Bar ◽  
Β Phase ◽  
Schmid Factor ◽  
Pressure Bar

In the present work, the localized features of adiabatic shear bands (ASBs) of our recently designed damage tolerance α+β dual-phase Ti alloy are investigated by the integration of electron backscattering diffraction and experimental and theoretical Schmid factor analysis. At the strain rate of 1.8 × 104 s−1 induced by a split Hopkinson pressure bar, the shear stress reaches a maximum of 1951 MPa with the shear strain of 1.27. It is found that the α+β dual-phase colony structures mediate the extensive plastic deformations along α/β phase boundaries, contributing to the formations of ASBs, microvoids, and cracks, and resulting in stable and unstable softening behaviors. Moreover, the dynamic recrystallization yields the dispersion of a great amount of fine α grains along the shearing paths and in the ASBs, promoting the softening and shear localization. On the contrary, low-angle grain boundaries present good resistance to the formation of cracks and the thermal softening, while the non-basal slipping dramatically contributes to the strain hardening, supporting the promising approaches to fabricate the advanced damage tolerance dual-phase Ti alloy.

scholarly journals Experimental investigation of bending characteristics of hybrid composites fabricated by hand layup method

2021 ◽  
Vol 2089 (1) ◽  
pp. 012033
Author(s):  
M Sadashiva ◽  
S Praveen Kumar ◽  
M K Yathish ◽  
V T Satish ◽  
MR Srinivasa ◽  
...  
Keyword(s):  
Composite Materials ◽  
Hybrid Composite ◽  
Polyester Resin ◽  
Hybrid Composites ◽  
Bending Test ◽  
Environment Friendly ◽  
Longitudinal Fiber ◽  
Develop Environment ◽  
The One ◽  
Better Than

Abstract The extensive applications of hybrid composite materials in the field of transportation and structural domine provide prominent advantages in the order of stiffness, strength even cost. However extend the advantages of hybrid campsites in several field such as aviation and marine even more additional properties should be inculcate in them. During production of such profitable composites poses some problems at time at decompose and processing. It’s better to develop environment friendly and reusable composites, bio hybrid composite materials such of the one. In this paper, focused on development of Eco-friendly hybrid bio composites with the ingredients of drumstick fibers, glass fiber along with polyester resin. This hybrid bio composites subjected to bending test and evaluate the characteristics of bending properties, this research evident that bending characteristics of hybrid composites with longitudinal fiber orientation better than transverse.

scholarly journals Effect of Dissolution of η′ Precipitates on Mechanical Properties of A7075-T6 Alloy

2022 ◽  
Vol 60 (1) ◽  
pp. 83-93
Author(s):  
Young-We Kim ◽  
Yong-Hee Jo ◽  
Yun-Soo Lee ◽  
Hyoung-Wook Kim ◽  
Je-In Lee
Keyword(s):  
Mechanical Properties ◽  
Yield Strength ◽  
Solution Treatment ◽  
Aluminum Matrix ◽  
Natural Aging ◽  
Aging Treatment ◽  
Nucleation Site ◽  
Treatment Temperature ◽  
Solution Treatment Temperature ◽  
Bake Hardening

The effects of dissolution of the η′ phase by solution treatment on the mechanical properties of A7075-T6 alloy were investigated. Immediately after solution treatment of the T6 sheet at 450 oC or higher, elongation significantly increased and dissolution of the η′ phase occurred. η′ is the main hardening phase. After natural-aging, GPI, which is coherent with the aluminum matrix, was formed and strength increased. When bake hardening after natural-aging was performed, the yield strength slightly increased due to partial dissolution of the GPI and re-precipitation of the η′ phase. In contrast, after solution treatment at 400 oC, there was less elongation increase due to the precipitation of the coarse η phase at grain boundaries and low dissolution of the η′ phase. In addition, when bake hardening after natural-aging was performed, the yield strength decreased due to insufficient GPI, which is the nucleation site of the η′ phase. To promote reprecipitation of the η′ phase, the solution treatment temperature was set to a level that would increase solubility. As a result, the yield strength was significantly increased through re-precipitation of a large number of fine and uniform η′ phase. In addition, to increase the effect of dissolution, a pre-aging treatment was introduced and the bake hardenability can be improved after dissolution.

The Metastable Phase Responsible for Hardenig in an Al-Mg Alloy Aged at 473K

2013 ◽  
Vol 748 ◽  
pp. 123-127 ◽  
Author(s):  
Koichiro Fukui ◽  
Ayaka Mori ◽  
Masanori Mitome ◽  
Mahoto Takeda
Keyword(s):  
Precipitation Hardening ◽  
Vickers Microhardness ◽  
Layer Structure ◽  
Metastable Phase ◽  
Mg Alloy ◽  
Stable Phase ◽  
Precipitation Behavior ◽  
Dsc Measurements ◽  
Β Phase ◽  
Phase Precipitate

The present work investigated precipitation behavior in an Al-17at%Mg alloy isothermally aged at 473K, by means of Vickers microhardness tests, DSC measurements and TEM observations. A quantitative analysis of DSC measurements revealed that the metastable β-phase precipitates mainly contribute to precipitation hardening of this alloy aged at 473K. The present STEM-EDX observations confirmed that the metastable β-phase precipitate has a layer structure with a composition similar to the stable phase (Al3Mg2).

Hot Workability Map for Near-α Titanium Alloy Ti-5.6Al-4.8Sn-2Zr-1Mo-0.35Si-0.7Nd

2012 ◽  
Vol 482-484 ◽  
pp. 1453-1456
Author(s):  
Ming Man Li ◽  
Qui Jian Xun ◽  
Shang Zhou Zhang
Keyword(s):  
Titanium Alloy ◽  
Dynamic Recrystallization ◽  
Power Dissipation ◽  
Processing Map ◽  
Flow Instability ◽  
Shear Bands ◽  
Hot Workability ◽  
Adiabatic Shear Bands ◽  
Β Phase ◽  
Power Dissipation Efficiency

The characterizations of hot working behavior of a near-α titanium alloy using the approach of processing maps are described. Processing map in the α+β region exhibit a domain of the globularization process of lamellar structure and α dynamic recrystallization with a power dissipation efficiency of 0.6-0.9. In the β region the map exhibited a domain centered around 1060°C and 0.1 s-1with a power dissipation efficiency of 0.76 where the β phase undergoes dynamic recrystallization. At higher strain rate flow instability occurs in the α+β region due to adiabatic shear bands formation as well as in the β region due to flow inhomogeneity of β phase.

Influences of Aging History on Low Temperature Performance of Asphalt Concrete

2008 ◽  
Vol 385-387 ◽  
pp. 493-496 ◽  
Author(s):  
Shao Peng Wu ◽  
Guo Jun Zhu ◽  
Ling Pang ◽  
Cong Hui Liu
Keyword(s):  
Low Temperature ◽  
Flexural Strength ◽  
Asphalt Concrete ◽  
Tensile Strain ◽  
Natural Aging ◽  
Bending Stiffness ◽  
Bending Test ◽  
Stiffness Modulus ◽  
Stone Mastic Asphalt ◽  
High And Low Temperatures

According to three-point bending test, this paper explores the influence of low temperature on the flexural strength, the tensile strain and bending stiffness modulus of the aged Stone Mastic Asphalt (SMA-13) concrete. The asphalt mixtures are aged according to the short-term aging (at 135°C, 4 hours), and long-term aging (asphalt concrete at 85°C, 120 hours) and natural aging (3 months, 6 months and 9 months). The result shows that, with the same loading rate, the tensile strain of specimens at -30°C are smaller than those at -10°C; but when temperature is certain, the tensile strain of specimens lager than those of aged specimens. The longer the aging time lasts, the more flexural strength differences between high and low temperatures can be found. A pretty well index variation can be found between the tensile strain and temperature. The same trend also appears between the bending stiffness modulus and temperature of SMA-13 asphalt concrete.

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