• Advances in nano research
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• v.14 no.2
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• pp.155-164
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• 2023

Grain size in sheet metals in one of the main parameters in determining formability. Grain size control in industry requires delicate process control and equipment. In the present study, effects of grain size on the formability of steel sheets is investigated. Experimental investigation of effect of grain size is a cumbersome method which due to existence of many other effective parameters are not conclusive in some cases. On the other hand, since the average grain size of a crystalline material is a statistical parameter, using traditional methods are not sufficient for find the optimum grain size to maximize formability. Therefore, design of experiment (DoE) and artificial intelligence (AI) methods are coupled together in this study to find the optimum conditions for formability in terms of grain size and to predict forming limits of sheet metals under bi-stretch loading conditions. In this regard, a set of experiment is conducted to provide initial data for training and testing DoE and AI. Afterwards, the using response surface method (RSM) optimum grain size is calculated. Moreover, trained neural network is used to predict formability in the calculated optimum condition and the results compared to the experimental results. The findings of the present study show that DoE and AI could be a great aid in the design, determination and prediction of optimum grain size for maximizing sheet formability.

• Journal of Welding and Joining
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• v.1 no.2
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• pp.61-68
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• 1983

Austenitic stainless steel has been investigated widely for creep strength of heat resistant material and effects of grain sizes due to various solution treatment time under constant temperature. It was studied that effects of grain sizes subject to solution treatment temperature 1100.deg. C, 1125.deg. C, 1175.deg. C, 1250.deg C, and 1300.deg. C respectively on the creep strength, fracture behaviour and fractography of SUS 316 stainless steel. The experimental results obtained were as follows. 1. The optimum grain size for the maximum creep strength did not vary with creep testing temperatures and stress levels. 2. Among various grain sizes due to different solution treatment temperature, the optimum grain size for the creep strength was found 0.044mm. Also the size showed the minimum initial strain regardless creep temperature. 3. Garofalo's equation of creep rupture life was applied well to SUS 316 stainless steel. 4. The fractography of optimum size was ductile intergranular fracture of dimple type and showed along with the increase of grain size intergranular fracture of w type.

• Magazine of the Korean Society of Agricultural Engineers
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• v.22 no.3
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• pp.46-59
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• 1980

This study was conducted to obtain the most effective distribution of grain size and the optimum lime content for lime-soil stabilization. To achieve the aim, the change of consistency, the characteristics of compaction and unconfined compressive strength were tested by adding of 0, 4, 6, 8, 10 and 12 percent lime by weight for all soils adjusted by given ratios of sand to clay. The results obtained were as follows; 1. There was a tendency that the plasticity index of lime-soil mixture was decreased by increasing the amount of lime, whereas the liquid limit was varied irregularly and the plastic limit was increased. 2. With the addition of more lime, the optimum moisture content of lime-soil mixture was increased, and the maximum dry density was decreased. 3. The optimum lime content of lime-soil mixture was varied from soil to soil, and the less amount of small grain size, the less value of optimum lime content. 4. The optimum distribution of grain size for lime-soil mixture was in the soil, having the ratio of about 60 percent of cohesive clay and about 40 percent of sand by weight. 5. In the soil having fine grain size, the effect of curing appeared for long periods of time, whereas the increasing rate of unconfined compressive strength was great on the soil of coarse grain size in the earlier stage of curing period.

• 한국기계연구소 소보
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• s.20
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• pp.71-78
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• 1990

This investigation was undertaken to establish the technologies of grain refinement and modification, and to characterize material properties, essential for high quality aluminum alloy castings. Grain refinement seldom changed DAS and eutectic Si size, but largely decrease grain size. The variations of grain size induced by grain refinement had a great influence on the elongation without changes in the tensile strength or yield strength. The optimum Ti level lies between 0.1% and 0.16% to achieve the best possible mechanical properties. DAS and grain size were little affected, but eutectic Si size was greatly refined by modification. The variation of eutectic Si size had a great effect on the elongation, impact value, fracture toughness and fatigue crack propagation rate without changes in the tensile strength or yield strength. The Sr content of 0.015% is optimum to modification.

• Magazine of the Korean Society of Agricultural Engineers
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• v.11 no.4
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• pp.1783-1790
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• 1969

It is one of the most economical method of soil stabilization works to compact soil, which increases soil density artificially. Compaction effort is to lessen void of soils, and consequently its aim is to enlarge friction and cohesion force, and reduce permeability of soil. Factors in compaction effort are moisture content, grain size, grain size distribution, physical properties, compaction method and temperature of soils etc. The results obtained in this study on the effects that grain size, gradation and physical properties influence upon compaction effort for 20 samples under the constant compaction method, are summarized as follows: 1. The bigger the maximum dry density is, the smaller the optimum moisture content is, on the other hand, the smaller the maximum dry densityis, the bigger the optimum moisture content is, ingeneral. 2. The coarser the grain size is, the bigger the maximum dry density is, and the optimum moisture content becomes small, and dry density-moisture content curve has the sharp peak, generally. Also, the finer the grain size is the smaller the maximum dry density is, and the optimum moisture content shows the big value, and dry density-moisture content curve has the dull peak. 3. The maximum dry density shows the biggest value on the sample to be about 15% of particles finer than No. 200 sieve. The more the percent passing of No. 10 sieve increase, the smaller the maximum dry density is. Soils which have uniformity coefficient less than 5 in particles larger than 0.074mm hardly show dry density-moisture content curve. 4. There is a relation which is ramax＝2.3948-0.0376 Wopt between the maximum dry density and the optimum moisture content, namely, the maximum dry density is increased in proportion to decrease of the optimum moisture content. 5. There are relations to be the straight lines which the maximum dry density decrease, on the other hand, the optimum moisture content increase in accordance with enlargement of Atterberg Limit(LL, PL, PL) in compacted soils.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.14 no.10
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• pp.815-820
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• 2001

The piezoelectric properties of the PT-PZ-PNN system ceramics were investigated depending on the variati on of the grain size. The grain size was varied by sintering temperature, and additive. The effect of the grain size on the electrical, dielectric, and piezoelectric properties was studied with respect to the feasibility of the application for the piezoelectric transformer. Grain size increased as the PMW contents increased. The smaller the particle size used, the smaller the grain size obtained. Specimens are densily sintered. Dielectric and piezoelectric properties are not always improved in proportion to the grain sizes. When he particle size are fine and the grain size are increased properly with the optimum additives, the piezoelectric preperties have good values. the specimen sintered at 1200$\^{C}$ with PMW 2 mol% and MnO$\_$2/ 0.5wt% contents exhibited good piezoelectric properties for a piezoelectric transformer.

• Magazine of the Korean Society of Agricultural Engineers
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• v.45 no.3
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• pp.50-58
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• 2003

Due to the economic growth and the improvement of life standards in the country, the quantities of waste glasses have been yearly increased. About 65% of them are recycled and the rest are reclaimed. The reclaimed waste glasses can cause some problems such as the environmental pollution as well as the processing cost of them. Thus, the purpose of this experimental research is to investigate the properties of mortar using powdered waste glasses(PWG) as a cementitious materials in mortar to recycle the reclaimed waste glasses For this purpose, the workability and strength of mortar specimens using PWG have been tested and analyzed in various grain size of them by changing the replacement ratio. As a result, considering the workability and strength of mortar specimens using PWG, it is concluded that the optimum grain size and replacement ratio of them will be existing.

• Journal of the Korean Society for Heat Treatment
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• v.4 no.1
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• pp.37-41
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• 1991

In this study, the effect of solution treatment temperature on the tensile property in intermediate thermo-mechanical treated Al-Li alloys are investigated. After the intermediate thermo-mechanical treated Al-Li, Al-Li-Mg and Al-Li-Mg-Zr alloys were solution treated at various temperatures (500, 520 and $540^{\circ}C$), these were aged at $190^{\circ}C$, $240^{\circ}C$ and tested tensile properties. The results obtained from the experiment are as follows ; 1) The optimum solution heat-treatment temperature is $540^{\circ}C$ for a Al-Li alloy, and the recrystallized grain size is about $70{\mu}m$. 2) The optimum solution heat-treatment temperature is $500^{\circ}C$ for a Al-Li-Mg alloy, and the recrystallized grain size is the most coarse in all alloys. 3) The tensile property is independent of the solution treatment temperature in a Al-Li-Mg-Zr alloy, and the recrystallized grain size is the finest owing to addition of Zr.

• Proceedings of the Korea Concrete Institute Conference
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• 1998.10c
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• pp.36-41
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• 1998

Recently, it has been reported that recycling of wasted glasses should be a hot issue in related business field. Thus, the purpose of this experimental research is to recycle wasted glasses by substituting for the cement in mortar and concrete. As a pilot test, workability and the strength of mortar with recycled glass have been tested and analyzed according to replacement ratio of recycled glass with grain size of them. As a result, considering the workability and the strength of mortar containing recycled glass, the existence of the optimum replacement ratio and grain size of them have been obtained.

• Applied Microscopy
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• v.1 no.1
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• pp.3-10
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• 1969

By the use of electron microscope, the study has beek made on the grain size in photo graphic emulsions, which are made at different temperature. It is found that ,the optimum temperature is $60^{\circ}C$, at which the average grain size obtained is the biggest. Also electron micrographs show NaCl-type crystal structure of AgBr and AgCl, as we expected.