• Journal of Power System Engineering
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• v.21 no.3
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• pp.37-44
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• 2017

In this study, failure analysis of the angular pin for molding machines to aluminum component molding was carried out. SM45C steel was used for the angular pin, it was surface hardened by the induction surface hardening heat treatment. The cross section of damaged angular pin was observed, and micro Vickers hardness value from the fractured part was measured. Brittle fracture was occurred from the fracture surface of angular pin, therefore, impact toughness value was evaluated by V-notch Charpy impact test. It was confirmed that the impact absorption energy was high when was tempered at a high temperature for a long time, and the toughness was slightly increased. Also, 2-parameter Weibull statistical analysis was investigated in order to evaluate the reliability of the measured micro Vickers hardness values and absorbed energy. The micro Vickers hardness and absorbed energy well followed a two-parameter Weibull probability distribution, respectively. The reverse design against angular pin was proposed as possible by using test results.

• Composites Research
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• v.17 no.4
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• pp.53-60
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• 2004

This paper describes a method for a falling weight impact test to estimate the impact energy absorbing characteristics and impact strength of CFRP laminate plates based on considerations of stress wave propagation theory. The absorbed energy of T300 orthotropic composites is higher than that of quasi-isotropic specimen over impact energy 6.8J, but in case of using T700 fiber, much difference does not show. Also, absorbed energy of T300 orthotropic composites, which are composed of the same stacking number and orientation became more than that of T700 fiber specimen; however there was no big difference in case of quasi-isotropic specimens. The delamination areas of the impacted specimen were measured with the ultrasonic C-scanner to find correlation between impact energy and delamination area. The fracture surfaces were observed by using the SEM (scanning electron microscope) through a low-velocity impact test in order to confirm the fracture mechanism.

• Transactions of the Korean Society of Mechanical Engineers
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• v.7 no.4
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• pp.372-378
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• 1983

Use of dual phase steel are growing for its high strength and light weight in automobiles. The effect of the martensite volume fraction with various impact velocities on the strength, ductility and absorbed energy of dual phase (ferrite-martensite) steels were investigated in low carbon 1.5% Mn steels which were soaked at 700.deg. C, 730.deg. C, 780.deg. C, and brine quenched. Both the yield load and the maximum impact load increased when the martensite volume fraction increased, the loading time and the absorbed energy of the specimen decreased when the martensite volume fraction increased.

• Korean Journal of Materials Research
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• v.29 no.3
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• pp.189-195
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• 2019

The effect of C, Mn, and Al additions on the tensile and Charpy impact properties of austenitic high-manganese steels for cryogenic applications is investigated in terms of the deformation mechanism dependent on stacking fault energy and austenite stability. The addition of the alloying elements usually increases the stacking fault energy, which is calculated using a modified thermodynamic model. Although the yield strength of austenitic high-manganese steels is increased by the addition of the alloying elements, the tensile strength is significantly affected by the deformation mechanism associated with stacking fault energy because of grain size refinement caused by deformation twinning and mobile dislocations generated during deformation-induced martensite transformation. None of the austenitic high-manganese steels exhibit clear ductile-brittle transition behavior, but their absorbed energy gradually decreases with lowering test temperature, regardless of the alloying elements. However, the combined addition of Mn and Al to the austenitic high-manganese steels suppresses the decrease in absorbed energy with a decreasing temperature by enhancing austenite stability.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2013.05a
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• pp.1307-1308
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• 2013

• Proceedings of the KSME Conference
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• 2001.06a
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• pp.517-522
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• 2001

The purpose of this study is to investigate the thermal embrittlement and the mechanical properties of 2.25Cr-1Mo steel aged at high temperature and stress for 250 hours. Original, aged artificially material were tested to obtain the hardness and impact absorbed energy. Hardness and impact absorbed energy decreased with the increasing aging time. The carbide morphology with the thermal embrittlement was found to contribute to the mechanical property change by X-Ray diffraction method.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.24 no.7 s.178
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• pp.1771-1778
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• 2000

The purpose of this study is to investigate the thermal embrittlement and the mechanical properties of 2.25Cr-1Mo steel aged at high temperature for the extended periods. Original, aged artificiall y and used material were tested to obtain the tensile strength, hardness and impact absorbed energy. Tensile strength, hardness and impact absorbed energy decreased with the increasing aging time. The carbide morphology with the thermal embrittlement was found to contribute to the mechanical property change by X-Ray diffraction method.

• Journal of Welding and Joining
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• v.32 no.4
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• pp.63-68
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• 2014

This paper has an aim to study the effect of PWHT and its conditions(peak temperature and holding time) on the tensile properties and impact toughness of FCAW weld metal in relation to microstructure. Impact toughness was evaluated to apply the cargo tank of liquified gas carriers under the various PWHT condition of each class societies. On the basis of these study, it was found that PWHT conditions within all class societies affect charpy absorbed energy of weld metal little or no, all PWHT weld metals kept similar level of charpy absorbed energy as as-weld weld metal down-to $-60^{\circ}C$ and finally indicated lower energy value than that of as-weld weld metal at $-75^{\circ}C$. It is because the precipitation of 2nd phase was controlled from welding consumable and the grain size was grown by PWHT.

• Journal of Korea Foundry Society
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• v.26 no.6
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• pp.258-266
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• 2006

The purpose of this study was to investigate the effects of silicon and nickel additions that influenced the impact and tensile properties of heavy section as-cast ductile irons for wind mill. Based on the results of the metallographic analysis and the mechanical testing on the 2.0 wt.%Si (LS group) and 2.4 wt.%Si (HS group) ductile irons, which contains 0.0, 0.3, 0.6 and 0.9 wt.%Ni, respectively, the following conclusions could be obtained. The nickel additions increased the tensile properties, the microhardness of pearlite, and the pearlite fraction of matrix for the specimen with the same silicon content. The mechanical properties of LS group specimen were in the range of the specification for the ductile iron wind mill castings. The LS group specimens showed higher absorbed impact energy at room temperature and $-20^{\circ}C$ than that of the HS group specimens. However, the absorbed impact energy at $-20^{\circ}C$ for the HS group specimens was observed to be sharply decreased under 10 J by addition of the nickel.

• Journal of Radiation Industry
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• v.5 no.2
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• pp.145-149
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• 2011

Poly(butylenes terephthalate) have made large strides in applications of injection, extrusion, and molding material due to their excellent thermal resistance and appropriate mechanical properties. However, PBT was not hard polymer but a soft polymer which caused low absorption of external energy and the defect of being easily broken with the strong impact. Thus, the electron beam irradiation was carried out over a range of irradiation doses from 100 to 1,000 kGy for enhancing the properties. The decreases of $T_m$, $T_c$, and enthalpy were observed as increasing the absorbed dose in the results of DSC analysis. The improvement in the impact strength of PBT was clearly observed as the absorbed dose was increased. This was probably due to the 3-dimensional network structures, resulting in increasing the absorption of impact energy. In addition, the wear properties had increased at higher than 300 kGy. The negative deviation of weight loss confirmed the improvement of the wear properties of PBT, as evidenced by SEM observation on the wear surfaces.