• KOREAN JOURNAL OF CROP SCIENCE
• /
• v.48 no.1
• /
• pp.13-16
• /
• 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.

• The Korean Journal of Food And Nutrition
• /
• v.11 no.4
• /
• pp.369-374
• /
• 1998

This study was conducted to investiagte influences of cold aged dough on the quality of bagutte. After 2 hours fementing, the dough was divided 2 parts and they were stored in the refrigirated adjusted 1∼-1$^{\circ}C$. The cold aging time was 24, 48 hours respectivley. After 2 hourse fermentation, the dough's pH was 5.45 and 24, 48 hours cold aged dough were 4.99, 4.81. During cold aging, the difference of pH was not significant. The main organic acids in the baguette were lactic acid, acetic acid and malic acid, Among these organic acids, the acetic acid was the largest quantity regardlessly in different fermentation and the cold aging acids, time. Right after baking, the enthalphy of all samples were almost same even thought in different cold aging time, but during different storage periods they showed the difference of retrogradation by the increase of the enthalphy. 24 hours cold aging baguette had the best taste, aroma and texture in bread's score sheet.

• Proceedings of the Korean Society for Technology of Plasticity Conference
• /
• 2008.10a
• /
• pp.203-206
• /
• 2008

Transformation of austenite to martensite during cold rolling has been widely used to strengthen metastable austenitic stainless steel grades. Aging treatment of cold worked metastable austenitic stainless steels, including ${\alpha}'$-martensite phase, results in the further increase of strength, when aging is performed in $200^{\circ}C$ to $450^{\circ}C$ temperature range. The purpose of the present study was to evaluate the effect of time and temperature on the stress-strain behavior of cold worked austenitic stainless steels. The amount of ${\alpha}'$-martensite during cold working and aging was examined by ferrite scope and X-ray diffraction (XRD). During aging at $450^{\circ}C$ for 1hr, tensile strength dramatically increased by 150MPa. Deformed metastable austenitic steels containing the "body-centered" ${\alpha}'$-martensite are strengthened by the diffusion of interstitial solute atoms during aging at low temperature.

• Nuclear Engineering and Technology
• /
• v.53 no.6
• /
• pp.1909-1923
• /
• 2021

We experimentally investigated the effects of thermal aging and cold work on the microstructure, mechanical properties, and primary water stress corrosion cracking (PWSCC) initiation time for Alloy 182 welds. The effects of thermal aging and cold work on the PWSCC initiation time of Alloy 182 were modeled based on the plastic energy concept and the PWSCC initiation data of this study and previous reports by considering censored data. Based on the results, it is estimated that the PWSCC resistance of the Alloy 182 weld firstly increases and then decreases with thermal aging time when the applied stress is kept constant.

• Textile Coloration and Finishing
• /
• v.29 no.3
• /
• pp.155-161
• /
• 2017

In CPB(Cold-Pad-Batch) dyeing, the rubber of the padder roll is influenced by the heat, chemical and mechanical influences and thus aging of the padder roll rubber occurs. This study presents an accelerated thermal aging test of the CPB padder roll rubber with strong alkali conditions. Using Arrhenius formula of the various property values for the various aging temperatures($80^{\circ}C$, $90^{\circ}C$, $100^{\circ}C$) of the padder roll, the accelerated life predictions could be calculated. The threshold value of the property was set at different values. The hardness was set at the point where 5% degradation occurs based on the actual use conditions, and the tensile strength was set at the point where 50% degradation occurs based on the general life prediction standards. From the results of the different physical properties at differing temperatures, the Arrhenius plot could be obtained. Through the usage of the Arrhenius Equation, significant duration expectation could be predicted, and the chemical aging behavior of the CPB padder roll could be found at the arbitrary and actual temperatures.

• Korean Journal of Materials Research
• /
• v.8 no.4
• /
• pp.354-358
• /
• 1998

Effect of cold drawing ratio and aging time on the hardness of lnconel 718 wire aged at 11l6K were investi¬gated by hardness measurement and scanning & transmission electron microscopy. Hardness which was 245Hv in as¬solution treated condition increased very rapidly to 450Hv as cold drawing ratio increased to 50%. The hardness in the early stage of aging was increased by the precipitation of $\gamma^{'}$ and $\gamma^{'}$ phases and after the peak hardness, the hardness was decreased by the transformation of $\gamma^{'}$ phase to $\delta$ phase. The time to reach peak hardness during aging appeared to be reduced with the increase of cold drawing ratio, and those times were 30, 10, and 5 minutes for 0, 30 and 50% cold drawn materials, respectively. For the 50% cold drawn material. $\gamma^{'}$ and $\gamma^{'}$ were precipitated by aging for 5 minutes at 1116K. The hardness in the same material was largely decreased under the initial hardness by the recrystallization.

• Korean Journal of Materials Research
• /
• v.29 no.6
• /
• pp.392-397
• /
• 2019

A cold roll-bonding process is applied to fabricate an AA6061/AA5052/AA6061 three-layer clad sheet. Two AA6061 and one AA5052 sheets of 2 mm thickness, 40 mm width, and 300 mm length are stacked, with the AA5052 sheet located in the center. After surface treatment such as degreasing and wire brushing, sample is reduced to a thickness of 1.5 mm by multi-pass cold rolling. The rolling is performed at ambient temperature without lubricant using a 2-high mill with a roll diameter of 400 mm at rolling speed of 6.0 m/sec. The roll bonded AA6061/AA5052/AA6061 complex sheet is then hardened by natural aging(T4) and artificial aging(T6) treatments. The microstructures of the as-roll bonded and age-hardened Al complex sheets are revealed by optical microscopy; the mechanical properties are investigated by tensile testing and hardness testing. After rolling, the roll-bonded AA6061/AA5052/AA6061 sheets show a typical deformation structure in which grains are elongated in the rolling direction. However, after T4 and T6 aging treatment, there is a recrystallization structure consisting of coarse equiaxed grains in both AA5052 and AA6061 sheets. The as roll-bonded specimen shows a sandwich structure in which an AA5052 sheet is inserted into two AA6061 sheets with higher hardness. However, after T4 and T6 aging treatment, there is a different sandwich structure in which the hardness of the upper and lower layers of the AA6061 sheets is higher than that of the center of the AA5052 sheet. The strength values of the T4 and T6 age-treated specimens are found to increase by 1.3 and 1.4 times, respectively, compared to that value of the starting material.

• Korean Journal of Materials Research
• /
• v.32 no.3
• /
• pp.161-167
• /
• 2022

A cold roll-bonding process is applied to fabricate an AA6061/AA5052/AA6061/AA5052 layered sheet. Two AA6061 and one AA5052 sheets of 2mm thickness, 40mm width and 300mm length are alternately stacked, then reduced to a thickness of 2.0 mm by multi-pass cold rolling after surface treatment such as degreasing and wire brushing. The rolling is performed at ambient temperature without lubricant using a 2-high mill with a roll diameter of 400 mm at a rolling speed of 6.0 m/sec. The roll-bonded AA6061/AA5052/AA6061/AA5052 layered sheet is then hardened by natural aging (T4) and artificial aging (T6) treatments. The microstructure of the as-roll bonded and the age-hardened Al sheets was revealed by SEM observation; the mechanical properties were investigated by tensile testing and hardness testing. After T4 and T6 aging treatment, the specimens had a recrystallization structure consisting of coarse equiaxed grains in both AA5052 and AA6061 regions. The as-roll-bonded specimen showed a clad structure in which the hardness of AA5052 regions was higher than that of AA6061 regions. However, after T4 and T6 aging treatment, specimens exhibited different structures, with hardness of AA6061 regions higher than that of AA5052 regions. Strengths of T6 and T4 age-treated specimens were found to increase by 1.55 and 1.36 times, respectively, compared to the value of the starting material.

• Korean Journal of Materials Research
• /
• v.33 no.12
• /
• pp.565-571
• /
• 2023

AA1050/AA6061/AA1050 layered sheet was fabricated by cold roll-bonding process and subsequently T4 and T6 aging-treated. Two commercial AA1050 sheets of 1 mm thickness and one AA6061 sheet of 2 mm thickness were stacked up so that an AA6061 sheet was located between two AA1050 sheets. After surface treatments such as degreasing and wire brushing, they were then roll-bonded to a thickness of 2 mm by cold rolling. The roll-bonded Al sheets were then processed by natural aging (T4) and artificial aging (T6) treatments. The as roll-bonded Al sheets showed a typical deformation structure, where the grains are elongated in the rolling direction. However, after the T4 and T6 aging treatments, the Al sheets had a recrystallized structure consisting of coarse grains in both the AA5052 and AA6061 regions with different grain sizes in each. In addition, the sheets showed an inhomogeneous hardness distribution in the thickness direction, with higher hardness in AA6061 than in AA1050 after the T4 and T6 age treatments. The tensile strength of the T6-treated specimen was higher than that of the T4-treated one. However, the strength-ductility balance was much better in the T4-treated specimen than the T6-treated one. The tensile properties of the Al sheets fabricated in the present study were compared with those in a previous study.

• Journal of Powder Materials
• /
• v.19 no.4
• /
• pp.317-321
• /
• 2012

In this study, Cu-5Ni-10Sn(wt%) spinodal alloy was manufactured by gas atomization spray forming, and the microstructural features and mechanical properties of Cu-5Ni-10Sn alloy have been investigated during homogenization, cold working and age-hardening. The spray formed Cu-5Ni-10Sn alloy consisted of an equiaxed microstructure with a mixture of solid solution ${\alpha}$-(CuNiSn) grains and lamellar-structure grains. Homogenization at $800^{\circ}C$ and subsequent rapid quenching formed a uniform solid solution ${\alpha}$-(CuNiSn) phase. Direct aging at $350^{\circ}C$ from the homogenized Cu-5Ni-10Sn alloy promoted the precipitation of finely distributed ${\gamma}$' or ${\gamma}-(Cu,Ni)_3Sn$ phase throughout the matrix, resulting in a significant increase in microhardness and tensile strength. Cold working prior to aging was effective in strengthening Cu-5Ni-10Sn alloy, which gave rise to a maximum tensile strength of 1165 MPa. Subsequent aging treatment slightly reduced the tensile strength to 1000-1100 MPa due to annealing effects.