• Journal of Mechanical Science and Technology
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• v.20 no.1
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• pp.42-50
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• 2006

To evaluate the fatigue lifetime of structures, it is necessary to identify the values of parameters through tests. From the viewpoint of time and cost it is difficult for engineers to get the necessary data through tests. In this study, we surveyed literature and proposed a procedure to identify the fatigue parameters expressed with the Brinell hardness and elastic modulus. After obtaining stress concentration factors by finite element analysis, we calculated fatigue notch factors using Peterson's formula. Taking into account the welding residual stress, which was also obtained by finite element analysis, we evaluated the fatigue lifetime of four kinds of welded joints using the proposed approach. The estimated results are in a good agreement with the experimental results.

• Journal of the Korean Wood Science and Technology
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• v.49 no.4
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• pp.360-370
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• 2021

For the purpose of finding new uses for Miscanthus sinensis var. purpurascens, this study first constructed boards with the particles of the plant and impregnated them with phenolic resin at resin impregnation rates of 30 ± 2%, 40 ± 2%, 50 ± 2%, and 60 ± 2%. The impregnated boards were then carbonized at the carbonization temperature of 800℃, after which their density and mechanical properties were examined according to the different resin impregnation rates. The results showed that density, flexural strength performance, Brinell hardness, and compressive strength increased as the resin impregnation rate increased, thus affecting the physical and mechanical properties of the ceramics made of M. sinensis var. purpurascens particles.

• Journal of Korea Foundry Society
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• v.43 no.6
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• pp.279-285
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• 2023

In order to predict the mechanical properties of ductile cast iron heat treated in an intercritical temperature range, samples machined from cast iron with a tensile strength of 450 MPa were heat-treated at various intercritical temperatures and air-cooled, after which a microstructural analysis and Brinell hardness test were conducted. As the heat treatment temperature was increased in the intercritical temperature range, the ferrite fraction in the ductile cast iron decreased and the pearlite fraction increased, whereas the nodularity and nodule count did not change considerably from the corresponding values in the as-cast condition. The Brinell hardness values of the heat-treated ductile cast iron increased gradually as the heat treatment temperature was increased. Based on the measured alloy composition, the fraction of each stable phase and the hardness model from the literature, the hardness of the ductile cast iron heat treated in the intercritical temperature range was calculated, showing values very similar to the measured hardness data. In order to check whether it is possible to predict the hardness of heat-treated ductile cast iron by using the phase fraction obtained from thermodynamic calculations, the volumes of graphite, ferrite, and austenite in the alloy were calculated for each temperature condition. Those volume fractions were then converted into areas of each phase for hardness prediction of the heat-treated ductile cast iron. The hardness values of the cast iron samples based on thermodynamic calculations and on the hardness prediction model were similar within an error range up to 27 compared to the measured hardness data.

• Journal of agriculture & life science
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• v.44 no.4
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• pp.21-27
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• 2010

This study was carried out to investigate the properties of woodceramics made from woody part of Broussonetia Kazinoki at different carbonizing temperatures of $600^{\circ}C$, $800^{\circ}C$, $1000^{\circ}C$and $1200^{\circ}C$. The physical and mechanical properties increased with increasing carbonizing temperature. The highest mean values of density, bending strength, Brinell hardness and compressive strength were $0.62g/cm^3$, $79kgf/cm^2$, $203kgf/cm^2$ and $129kgf/cm^2$, respectively. There were close correlations between density and bending strength, Brinell hardness and compressive strength and MOE and MOR.

• Journal of the Korean Society for Heat Treatment
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• v.15 no.3
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• pp.127-135
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• 2002

Shore hardness test was developed in 1906 to overcome the limit of Brinell hardness test. However, the detailed requirements on the tester was not clearly specified except the scale, i.e., 100 HS for high carbon steel and 10 HS for soft brass. As a result, the shore hardness was used for quite long time without well established standards. For the establishment of hardness standards, standard tester, standard procedure, and standard hardness block must be provided. So far the standard of Shore hardness was maintained by correlating Shore hardness scale to Vickers hardness through converting equation. This is the so called converted Shore hardness and it is not the true Shore hardness standard strictly. In this paper, the possibility of establishing Shore hardness standard based on the Shore standard hardness tester is reported.

• Journal of the Korean Society for Precision Engineering
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• v.21 no.9
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• pp.142-148
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• 2004

It is already known that hardness number of cold-forged product is in close conjunction with its effective strain. This paper presents the method to predict the relation between effective strains and hardness by using FE-simulation of hardness test from the conception that hardness indicates resistance to plastic deformation. The results of FE-simulation for the materials are compared with those of experiments and also compared with those of experiments in reference to show the feasibility of the proposed method. In addition, the present method was applied to the cold-forged product to verify the relation between hardness and effective strain. As a result, the predicted hardness number by the present method is in good agreement with experimental values. Prediction of hardness fur a cold-forged product comes to be possible by estimating the relation between effective strain and hardness using the proposed method in this study.

• Journal of the Korean Society of Industry Convergence
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• v.2 no.2
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• pp.125-130
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• 1999

It is already known that hardness value of cold-forged product is in close conjunction with its effective strain. This paper presents the method to predict the relation between effective strains and hardness values by using FE-simulation of hardness test from the conception that hardness indicates resistance to plastic deformation. The results of FE-simulation for the material with pre-strain arc compared with those of experiments of the references to show the feasibility of the proposed method.

• Journal of Korea Foundry Society
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• v.13 no.4
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• pp.333-341
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• 1993

The effects of alloying elements on the structure and mechanical properties of compacted/vermicular graphite cast irons containing copper, tin and molubdenum for producing pearlite matrix, and also containing phosphorus and boron for increasing wear resistance, were investigated. The Brinell hardness and ultimate tensile strength of the specimens with the range of compositions, [1.5% Cu-0.05% Sn-(0.2-0.4)% Mo-(0.2-0.6)% P-(0.035-0.070)% B], was found to fall within in the following range, depending on their composition; Brinell hardness of BHN 250-315, ultimate tensile strength of $28.1-40.3kg/mm^2$. It was also found within this experiment that CV graphite cast irons possessing higher amount of phosphide eutectic exhibit better wear resistance, but the wear resistance became deteriorate when the area fraction of phosphide eutectics exceed more than 10%. From these experimental results, it could be concluded that the CV graphite cast iron containing 1.5% Cu, 0.05% Sn, 0.4% Mo, 0.2% P and 0.035% B showed good mechanical and wear resistance properties.

• Journal of Power System Engineering
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• v.17 no.4
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• pp.109-114
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• 2013

In this study, the microstructure, mechanical properties and high temperature oxidation characteristics of HiSiMo and HiSiMoM ductile iron for exhaust manifold were investigated. The HiSiMoM ductile iron was developed by optimization of alloying element addition and casting design. The exhaust manifold prototype was fabricated using the HiSiMoM iron and this resulted in the weight saving of 0.73kg. The microstructures of the HiSiMo and HiSiMoM irons were similar each other and graphite nodularity was 89% and 93% respectively. Tensile strengths of them were 663.5 and 674.4 MPa and Brinell hardness were 235.3 and 243.9 respectively. Both irons showed parabolic weight gain behavior in high temperature oxidation atmosphere. Oxidation layer was divided into external and internal layers. The weight gain of the HiSiMoM iron was lower than that of the HiSiMo iron after isothermal oxidation test at $900^{\circ}C$. This should be rationalized by higher Si enrichment at the interface of the matrix and internal layer of the HiSiMoM iron.

• Journal of the Korean Society for Heat Treatment
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• v.20 no.4
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• pp.175-180
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• 2007

The hardness of cold-forged products is in close relationship with its effective strain. This study presented the estimating method of hardness for cold-forged SKH9 products without hardness tests in view of resistance to plastic deformation using finite element code, DEFORM$^{TM}$. The flow stress equation obtained from the compression test was only used as a basic data to estimate the relationship between effective strain and hardness. In addition, this new estimating method was applied to the cold-forged product which was widely used in industrial field to show the feasibility. As a result, the predicted hardness numbers through FE simulation showed good agreement with the measured hardness numbers. It is possible to estimate the hardness not by hardness tests, but by only computer simulations for the deformed products. Also, effective strain values were possibly estimated by measuring hardness numbers, and vice versa.