scholarly journals Effects of natural aging on bake hardening behavior of Al–Mg–Si alloys with multi-step aging process

2015 ◽  
Vol 65 (3) ◽  
pp. 86-93 ◽  
Author(s):  
Yasuo Takaki ◽  
Tetsuya Masuda ◽  
Equo Kobayashi ◽  
Tatsuo Sato
Keyword(s):  
Aging Process ◽  
Natural Aging ◽  
Bake Hardening ◽  
Hardening Behavior

scholarly journals Effects of Natural Aging on Bake Hardening Behavior of Al–Mg–Si Alloys with Multi-Step Aging Process

2014 ◽  
Vol 55 (8) ◽  
pp. 1257-1265 ◽  
Author(s):  
Yasuo Takaki ◽  
Tetsuya Masuda ◽  
Equo Kobayashi ◽  
Tatsuo Sato
Keyword(s):  
Aging Process ◽  
Natural Aging ◽  
Bake Hardening ◽  
Hardening Behavior

scholarly journals Effects of natural aging after pre-aging on clustering and bake-hardening behavior in an Al–Mg–Si alloy

2016 ◽  
Vol 116 ◽  
pp. 82-86 ◽  
Author(s):  
Yasuhiro Aruga ◽  
Masaya Kozuka ◽  
Yasuo Takaki ◽  
Tatsuo Sato
Keyword(s):  
Natural Aging ◽  
Bake Hardening ◽  
Hardening Behavior

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.

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.

Effect of annealing time and phosphorus addition on bake hardening behavior of ultra-low carbon bake hardening steel

2018 ◽  
Vol 25 (12) ◽  
pp. 1287-1295
Author(s):  
Xi-liang Zhang ◽  
Hua-feng Hou ◽  
Tao Liu ◽  
Qian Zhou ◽  
Hong-ji Liu ◽  
...  
Keyword(s):  
Annealing Time ◽  
Low Carbon ◽  
Bake Hardening ◽  
Phosphorus Addition ◽  
Hardening Behavior ◽  
Bake Hardening Steel

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.

Pathogenesis, Pathology and Genetics of Osteoarthritis

2021 ◽  
Author(s):  
Ferhat Ege
Keyword(s):  
Aging Process ◽  
Symptomatic Relief ◽  
Natural Aging ◽  
The Other ◽  
Joint Tissue ◽  
Proinflammatory Mediators ◽  
High Prevalence ◽  
New Treatments ◽  
Biomechanical Factors ◽  
Shed Light

Osteoarthritis (OA) is a condition with high prevalence worldwide. OA affects not only the articular cartilage, but the entire joint, including the subchondral bone, ligaments, capsule, synovial membrane and the periarticular muscles. Despite the fact that the risks associated with OA increase with age, it is not a part of the natural aging process. It typically involves the knee, hip, spine, hand and foot joints. Several factors play an important role in the pathogenesis of OA, including biomechanical factors, proinflammatory mediators and proteases. On the other hand, it was mostly the results of the studies conducted on the genetic, genomic and epigenetic aspects of OA, from among many of its underlying etiological factors, which shed light on the molecular processes involved in the etiopathogenesis of OA. As the mechanisms that cause joint tissue damage in OA come to light, the treatment of OA will go beyond just providing symptomatic relief. Consequentially, new treatments will emerge that will either slow or completely stop the progression of OA.

Bake-hardening behavior of cold-rolled CMnSi and CMnSiCu TRIP-aided steel sheets

2004 ◽  
Vol 151 (1-3) ◽  
pp. 141-145 ◽  
Author(s):  
Z.C. Wang ◽  
S.J. Kim ◽  
C.G. Lee ◽  
T.H. Lee
Keyword(s):  
Bake Hardening ◽  
Steel Sheets ◽  
Hardening Behavior ◽  
Cold Rolled

Natural Aging Behavior of Double-Sided MIG Welded A7N01-T5 Aluminum Alloy

2018 ◽  
Vol 941 ◽  
pp. 1155-1160
Author(s):  
Ying Li ◽  
Zhi Qiang Zhang ◽  
Jian Liu ◽  
Hua Yin ◽  
Chang Shu He
Keyword(s):  
Aluminum Alloy ◽  
High Speed ◽  
Aging Process ◽  
Weld Zone ◽  
Natural Aging ◽  
Middle Layer ◽  
Age Hardening ◽  
Aging Behavior ◽  
Epma Analysis ◽  
Zn Content

A heat treatable A7N01 (Al-Zn-Mg) aluminum alloy mainly used to fabricate high-speed train body structures was double-sided welded by MIG welding. The natural aging behavior of the joint was systematically studied by local and global mechanical property testing method. Based on TEM observation and EPMA analysis, the key factors that lead to different natural aging behavior among various regions of the joint were discussed. The global tensile strength of the joints increased obviously after natural aging. All the joint samples fractured in the weld zone, which demonstrated the weld zone was the weakest zone of the joints. And the strength of the global welds were depended on the microstructure and natural aging ability of the weld zone. Moreover, the increase of the tensile property of the three local regions in the weld zone after post natural aging decreased as Middle>lower>upper. The above phenomenon was also further confirmed by microhardness measurement. The age hardening behavior is greatly influenced by the concentration of strengthening precipitates forming element Zn. The Zn content in the weld zone determined by EPMA showed that element Zn was dispersed unevenly, which is attributed to the double V-groove design used in this work and Zn vaporization in the molten pool during welding. The Zn content in the middle layer metals is higher than that of the upper and lower layers, resulting in the remarkable hardening response for the middle layer of the weld zone during natural aging process. Additionally, the solution zone containing the same Zn content as the base metal and undergoing sufficient solid solution during welding was found to possess the high hardening ability after natural aging process.

Sign in / Sign up

Export Citation Format

Share Document