scholarly journals Effects of Mg, Si contents and natural aging conditions on the bake hardenability of Al-Mg-Si alloys

2004 ◽  
Vol 54 (10) ◽  
pp. 412-417 ◽  
Author(s):  
Hidenori HATTA ◽  
Hiroki TANAKA ◽  
Shinichi MATSUDA ◽  
Hideo YOSHIDA
Keyword(s):  
Natural Aging ◽  
Aging Conditions ◽  
Bake Hardenability

Effects of Cu or Li Addition and Multi-Step Aging Conditions on the Bake-Hardenability of an Al-Mg-Si Alloy

2014 ◽  
Vol 794-796 ◽  
pp. 1152-1156 ◽  
Author(s):  
Yuki Koshino ◽  
Shoichi Hirosawa ◽  
Yasuhiro Aruga ◽  
Hisao Shishido ◽  
Katsushi Matsumoto
Keyword(s):  
Fuel Consumption ◽  
Volume Fraction ◽  
Natural Aging ◽  
Aging Treatment ◽  
Hardness Test ◽  
Specific Strength ◽  
Alternative Material ◽  
Aging Conditions ◽  
Microalloying Elements ◽  
Bake Hardenability

In recent years, automobiles with lower fuel consumption are required because the exhaust fume is severely regulated. The weight-saving is quite effective to realize such low fuel consumption, and therefore aluminum alloy becomes attractive as an alternative material of steels due to its high specific strength. 6XXX series Al-Mg-Si alloys exhibit good bake-hardenability during paint-bake treatment in the automobile manufacturing process, but to reduce further environmental impact, the paint-baking temperature is supposed to be lowered than the present temperature of about 443K. In this study, it was aimed to investigate the attained hardness after paint-bake treatment at various temperatures of 408-443K for an Al-0.55wt%Mg-0.90wt%Si alloy with/without microalloying elements of Cu and Li. The effects of multi-step aging conditions; e.g. pre-aging, natural aging and paint-bake treatments, were also investigated through Vickers hardness test, TEM observation and DSC analysis. From the obtained experimental results, it was clarified that the addition of Cu or Li to the Al-Mg-Si alloy increases the attained hardness even at a paint-baking temperature of 408K due to the increased volume fraction of precipitates. Furthermore, pre-aging treatment at 373K for 18ks was also effective in suppressing the increase in hardness during natural aging, resulting in the highest attained hardness among the investigated multi-step aging conditions; i.e. HV100 in the Li-added alloy paint-baked at 408K.

Accelerated Aging of Vulcanized Rubber. Factors Determining the Relation between Oven and Bomb Aging

1947 ◽  
Vol 20 (3) ◽  
pp. 760-768 ◽  
Author(s):  
R. G. Newton ◽  
J. R. Scott
Keyword(s):  
Accelerated Aging ◽  
Natural Aging ◽  
Relative Importance ◽  
Temperature Coefficients ◽  
Vulcanized Rubber ◽  
Relative Response ◽  
Aging Conditions ◽  
Moderate Range ◽  
Natural Rubber Vulcanizates ◽  
Theoretical Considerations

Abstract A study has been made of the influence of the following factors on the relative rates of tensile deterioration of natural rubber vulcanizates in the Geer oven and oxygen bomb, both at 70° C : period of vulcanization, sulfur ratio, nature of accelerator. Expressing this relation as the oven/bomb ratio, i.e., the ratio between oven and bomb aging periods that give the same deterioration, the following conclusions are drawn. (1) Varying the period of vulcanization of a given mix over a moderate range (2:3) around the optimum does not noticeably alter the oven/bomb ratio, except in unaccelerated mixes, where overvulcanization gave an abnormally low ratio, owing to the rubber perishing very rapidly in the oven. (2) The effect of varying the sulfur ratio within the usual limits for soft rubbers is small, and appears to result from the quicker vulcanization of the mixes richer in sulfur. (3) The nature of the accelerator profoundly affects the ratio, values ranging from 3 to 27 being found among the present mixes ; this effect is believed to be exerted through the influence of the accelerator both on rate of vulcanization and on the oxidizability of the vulcanizate. Theoretical considerations indicate that a rubber which vulcanizes quickly and (or) oxidizes slowly should give a low oven/bomb ratio, whereas one that vulcanizes slowly and(or) oxidizes quickly should give a higher ratio. The experimental data are generally in accord with this, and there is evidence that both rate of vulcanization and oxidizability can have an important effect, but the data do not enable the separate effect of each to be assessed exactly. The bearing of the results on the use of the oven and bomb tests is briefly discussed. It is shown that they demonstrate the fallacy of using a single factor for converting oven to bomb aging periods or vice versa, and that the relative natural aging resistances of widely different vulcanizates cannot be reliably assessed by either test, a limitation arising from the fact that the relative importance of oxidative decay and aftervulcanization varies from one type of mix to another, and that the temperature coefficients of these processes are not necessarily the same. These facts are very important in relation to the choice and application of accelerated aging tests for specification purposes, since these usually have to be applied to rubbers of unknown compositions, which are likely to vary widely in their relative response to different aging conditions.

scholarly journals Quantitative Trait Locus Mapping of Seed Vigor in Soybean under −20 °C Storage and Accelerated Aging Conditions via RAD Sequencing

2021 ◽  
Vol 43 (3) ◽  
pp. 1977-1996
Author(s):  
Rongfan Wang ◽  
Fengqi Wu ◽  
Xianrong Xie ◽  
Cunyi Yang
Keyword(s):  
Quantitative Trait ◽  
Accelerated Aging ◽  
Natural Aging ◽  
Storage Conditions ◽  
Seed Vigor ◽  
C Storage ◽  
Poor Seed ◽  
Aging Conditions ◽  
Trait Locus ◽  
Locus Mapping

Due to its fast deterioration, soybean (Glycine max L.) has an inherently poor seed vigor. Vigor loss occurring during storage is one of the main obstacles to soybean production in the tropics. To analyze the genetic background of seed vigor, soybean seeds of a recombinant inbred line (RIL) population derived from the cross between Zhonghuang24 (ZH24, low vigor cultivar) and Huaxia3hao (HX3, vigorous cultivar) were utilized to identify the quantitative trait loci (QTLs) underlying the seed vigor under −20 °C conservation and accelerated aging conditions. According to the linkage analysis, multiple seed vigor-related QTLs were identified under both −20 °C and accelerated aging storage. Two major QTLs and eight QTL hotspots localized on chromosomes 3, 6, 9, 11, 15, 16, 17, and 19 were detected that were associated with seed vigor across two storage conditions. The indicators of seed vigor did not correlate well between the two aging treatments, and no common QTLs were detected in RIL populations stored in two conditions. These results indicated that deterioration under accelerated aging conditions was not reflective of natural aging at −20 °C. Additionally, we suggest 15 promising candidate genes that could possibly determine the seed vigor in soybeans, which would help explore the mechanisms responsible for maintaining high seed vigor.

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.

Some Results Obtained in a Study of the Development of Stickiness by Vulcanized Rubber

1953 ◽  
Vol 26 (1) ◽  
pp. 136-142
Author(s):  
Lucien Toullec
Keyword(s):  
Natural Aging ◽  
Advanced Stage ◽  
Agent System ◽  
Experimental Conditions ◽  
Oxygen Bomb ◽  
Vulcanized Rubber ◽  
Aging Conditions ◽  
Small Capacity ◽  
Extreme State

Abstract The experiments described in the present paper show the possibility of reproducing artificially the stickiness which appears during natural aging, and the results show the experimental conditions which are most favorable to a study of the phenomenon. The indications are that it is best to use an oxygen bomb of small capacity, at a temperature of 60–70° C, and with a pressure of 1–4 kg. per sq. cm. of oxygen. The factor which under no conditions must be disregarded if almost certain failure is to be avoided is unquestionably the problem of ventilation. The Geer oven does not seem to be of any service in such experimentation. The appearance of stickiness during aging is not indicative of an advanced stage of deterioration, but is a manifestation of one form or type of aging rather than the consequence of an extreme state of deterioration. Finally, the influence of certain factors has been established. As far as factors inherent to the rubber mixtures themselves are concerned, the accelerator-vulcanizing agent system plays a determinant part. The character of the phenomenon depends on the aging conditions, particularly on the rate of oxidation. The tendency of a vulcanizate to become sticky on aging is particularly great when the temperature is relatively low and the pressure of oxygen is likewise low.

Thermochemical characterization of Zr/Fe2O3 pyrotechnic mixture under natural aging conditions

2019 ◽  
Vol 126 (10) ◽  
pp. 105113 ◽  
Author(s):  
Byung Heon Han ◽  
Yoocheon Kim ◽  
Seung-gyo Jang ◽  
Jeayong Yoo ◽  
Jack J. Yoh
Keyword(s):  
Natural Aging ◽  
Pyrotechnic Mixture ◽  
Aging Conditions

scholarly journals Effects of pre-aging at elevated temperature and natural aging on the bake hardenability of Al–Mg–Si alloy

2009 ◽  
Vol 59 (5) ◽  
pp. 248-253 ◽  
Author(s):  
Hidenori Hatta ◽  
Shinichi Matsuda ◽  
Hiroki Tanaka ◽  
Hideo Yoshida
Keyword(s):  
Elevated Temperature ◽  
Natural Aging ◽  
Bake Hardenability
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