• 열처리공학회지
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• 제32권2호
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• pp.57-60
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• 2019

The impact of two-step treatment on the mechanical properties of the 6061 Al alloy was investigated by testing the hardness and electrical conductance values. After two-step aging treatment, the hardness and electrical conductivity of the alloy was increased, and if the first aging treatment temperature was lower than the secondary aging treatment temperature, both the hardness and the electrical conductivity were not increased. The higher the temperature of the first aging treatment, the higher the hardness. The temperature of the first aging treatment is $175^{\circ}C$, $150^{\circ}C$, $120^{\circ}C$, and the second is $175^{\circ}C$ and $120^{\circ}C$.

• 열처리공학회지
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• 제7권4호
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• pp.270-276
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• 1994

The effects of thermomechanical and duplex aging treatment on precipitation behavior were investigated for the 8090 aluminium alloy by tensile test, hardness test, plane-strain fracture toughness test and electron microscope. Both pre-aging stretch and duplex aging with pre-aging stretch were effective to homogenize the distribution of S' phase in this alloys. The latter makes more homogeneous distribution of S' phase than that of the former, but the sizes of S' phase in both specimens are almost same. The size and distribution of 0' phase were not changed by thermomechanical or duplex aging treatment. The strength was increased by thermomechanical treatment, but the elongation was decreased. Duplex aging treatment couldn't change the strength and elongation. Pre-aging stretch and duplex aging with pre-aging stretch have same effect on the strength and elongation. The increase of strength by thermomechanical treatment in 8090 alumunium alloy was caused by homogeneously precipitated S' phase.

• 열처리공학회지
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• 제24권1호
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• pp.23-30
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• 2011

This study was carried out to investigate the effect of aging treatment on the mechanical properties and damping capacity of 12Cr heat resistant steel with ferrite phase. While hardness values in ferrite phase was not changed, that in martensite phase was dramatically dropped in early stage of aging treatment and then gradually decreased with increase of aging time. As aging treatment was carried out, the precipitation was not detected in ferrite phase, while carbides were precipitated in martensite phase. With increasing the aging time, tensile strength eventually decreased while impact toughness increased rapidly in the early stage of aging and then gradually increased. Besides, it was confirmed that damping capacity was not changed in the early stage of aging and then gradually increased with increase of aging time.

• 수산해양기술연구
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• 제20권1호
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• pp.23-29
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• 1984

고역알루미늄합금의 파괴특성에 미치는 시효열처리의 영향에 대하여 검토한 결과는 다음과 같다. 1. 현미경 조직의 관찰결과 $190^{\circ}C,$ 12hr로 시효열처리한 것이 시효강화된 양호한 조직과 미세한 석출분포를 나타내고 있음을 알 수 있었다. 2. 계단식시효열처리에 의하여 정상시효열처리보다 시효시간을 반정도로 단축시킬 수 있었고, 이들 조직도 유사하였다. 3. 인장파단면의 SEM 전자현미경 사진관찰결과는 $190^{\circ}C,$ 12hr으로 시효열처리한 것은 딤플형 입계 및 입내연성파괴를 나타내나, 이를 제외한 대부분은 시효열처리 시간과 온도에는 관계없이 입계연성파괴인 것이 관찰되었다.

• 한국작물학회지
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• 제48권1호
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• pp.13-16
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• 2003

Seeds of burcucumber were treated with accelerated aging, cold-stratification, and light quality illuminated during desiccation to enhance their germination and seedling emergence. The germination was increased by aging and cold-stratification although the latter treatment showed greater effectiveness than the former one. In the combined treatment of aging 6 days at $45^{\circ}C$ and cold-stratification, the germination was promoted under longer period of cold-stratification to reach nearly 100% in 3 week cold-stratification on the ninth day from sowing. In the sequentially combined treatment of aging, cold-stratification, and light quality during 24 hour desiccation at $35^{\circ}C$, no-stratified seeds showed the highest rate in red light treatment but the lowest in far-red light. This implies that the phytochrome action run during the desiccation of imbibed seeds. The red light exposure during drying for the cold-stratified seeds after aging accelerated the germination even more than the dark treatment and germinated 100% on the next day of sowing. It is concluded that the sequential treatment of aging, cold-stratification, and red light illumination during desiccation can highly promote percentage and speed of burcucumber seed germination.

• 열처리공학회지
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• 제33권5호
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• pp.226-231
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• 2020

The Cu-Co-Si alloy shows high strength by forming precipitates by aging precipitation heat treatment of supersaturated solid solution treated with solution treatment such as Cu-Ni-Si alloy, and the Co₂Si precipitated phase is dispersed in the copper matrix. The effect of aging treatment on the microstructure, mechanical and electrical properties of Cu-Co-Si alloys for electronic devices was investigated. As a results of SEM/EDS analysis, it was found that Co₂Si precipitates of 30~300 nm size were distributed in grains. By performing the double aging treatment, it was possible to improve the strength and electrical conductivity by dispersing the fine precipitate evenly.

• 한국산업융합학회 논문집
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• 제24권3호
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• pp.261-269
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• 2021

This study was evaluated the elastic wave properties according to tension of Incoloy 825 alloy with different solution treatment temperature and aging time. Solution treatment was carried out at 700, 800, 900, and 1000 ℃ for 1 hour, and aging was carried out at 700 ℃ for 1, 5, 10, and 30 hours. As the solution treatment temperature increased, the tensile strength decreased and the elongation increased. However, as the aging time increased, the tensile strength increased and the elongation decreased. The dominant frequency decreased as the solution treatment temperature increased, but increased as the aging time increased. The dominant frequency according to the solution treatment and aging time increased as the tensile strength increased, but increased despite the decrease in elongation.

• 열처리공학회지
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• 제15권1호
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• pp.21-24
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• 2002

The electrode materials for welding machine in automobile industry such as Cu-Cr, Cu-Zr and Cu-$Al_2O_3$ require the high electrical conductivity and the proper hardness. Therefore the effects of solution heat treatment and aging treatment on the electrical conductivity and hardness of Cu-0.8wt%Cr and Cu-1.2wt%Cr alloys have been investigated. Cu-0.8wt%Cr alloy showed the higher electrical conductivity and hardness than Cu-1.2wt%Cr alloy and both alloys showed the better electrical conductivity at $930^{\circ}C$ among 930, 980 and $1030^{\circ}C$ solution heat treatment temperatures. The electrical conductivity and hardness in both alloys were not affected by aging treatment but remarkably affected by solution heat treatment temperature. The final drawing process reduced electrical conductivity and increased hardness more in Cu-1.2wt%Cr alloy.

• 열처리공학회지
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• 제32권5호
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• pp.212-223
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• 2019

This study is to investigate the relationship between microstructural factors and tensile properties after aging heat treatment of the 15-5PH stainless steel at the temperature range of $450^{\circ}C$, $500^{\circ}C$ and $550^{\circ}C$ for various time. For the aging time of 2 hours, hardness showed maximum at $450^{\circ}C$ and then decreased with increasing aging temperature. While, hardness decreased gradually during aging $450^{\circ}C$, $500^{\circ}C$ and $550^{\circ}C$ from 1 hour to 5 hours but the hardness nearly unchanged until the 100 hours after 5 hours aging. When aging at $450^{\circ}C$, Cu atoms preferentially aggregated at the prior austenite grain boundaries and martensite lath boundaries, and Cu concentration at those boundaries was nearly unchanged even after aging for 100 hours. Therefore it was suggested that the coherency is still maintained after 100 hours aging at $450^{\circ}C$. Aging at $500^{\circ}C$ and $550^{\circ}C$ results in an increase in the concentration of Ni at the martensite lath boundaries and prior austenite grain boundaries, resulting in the formation of reversed austenite. Especially, when aged at $550^{\circ}C$ for 100 hours, the concentration of Ni remarkably increased at those boundaries, and thus the microstructure of herring bone shape was appeared. Considering the migration of Ni atom to the lath boundaries and prior austenite grain boundaries, Ni atoms contributed greatly to the formation of reversed austenite. On the other hand, it was found that Cu atoms hardly moving to those boundaries may not be contributed to the formation of reversed austenite. When aging at $450^{\circ}C$, the coarsening of the precipitated Cu atoms proceeded very slowly with increasing aging time, therefore the decrease in strengths were small but the reduction area was considerably increased due to the softening of the matrix. At the aging temperature of $500^{\circ}C$ and $550^{\circ}C$, the strengths decreased and the elongation and reduction area increased due to the appearance of the reversed austenite. Especially, the increase of reduction area was remarkable.

• Reproductive and Developmental Biology
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• 제37권4호
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• pp.281-287
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• 2013

In mammal, unfertilized oocytes remain in the oviduct or under in vitro culture, which is called "oocyte aging". This asynchrony negatively affects fertilization in pre- and post-implantation embryo development. Caffeine a phosphodiesterase inhibitor is known to rescue oocyte aging in several species. The objective of this study is to determine the cytoskeleton distribution in aged oocytes and the embryo developmental ability of aged oocytes in the present or absence of caffeine during maturation. Caffeine treatment increased the incidence of normal spindle assembly of aged oocytes (treatment, $67.57{\pm}4.11%$ aging, $44.61{\pm}6.4%$) and no significant differences compared to control group. Fluorescence values were compared using ROS (Reactive oxidation species) stain. Fluorescence values appear of control group intensity rate ($51.53.{\pm}3.80$), aging group ($68.10{\pm}5.54$) and treatment of caffeine ($45.04{\pm}2.98$). Aged oocytes that were derived from addition of caffeine to the IVM (in vitro maturation) medium had significantly increased 2-cell that developed to the blastocyst stage compared to the aging group. Blastocysts, derived from caffeine treatment group, significantly increased the total cell number compare aging ($90.44{\pm}10.18$ VS $67.88{\pm}7.72$). Apoptotic fragments of genomic DNA were measured in individual embryo using TUNEL assay. Blastocyst derived from caffeine treatment group decreased significantly the apoptotic index compared to blastocyst derived from aging group. In conclusion, we inferred that the caffeine treatment during oocyte aging can improve the developmental rate and quality in bovine embryos developing in vitro.