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송흥섭,김은표,박경진,류주하,Song Heung Sub,Kim Eun Pyo,Park Kyung Jin,You Joo Ha 한국분말야금학회 2004 한국분말재료학회지 (KPMI) Vol.11 No.5
A new concept of tungsten heavy alloy composite was suggested and manufactured in this study for the kinetic energy penetrator. The composite heavy alloy was composed of two parts, the center was molybdenum added heavy alloy compositions which were designed to promote the self-sharpening effect and outside was conventional heavy alloy in order to sustain the severe stress condition in the muzzle during the firing. The center part showed an intergranular and brittle mode at tungsten/tungsten interfaces by which self-sharpening effect could be activated. On the other hand, that of outside showed conventional ductile fracture mode under high strain rate condition. From the sub-scale penetration test, the depth of penetration in heavy alloy composites showed greater values than those of conventional tungsten heavy alloys. It is suggested that the heavy alloy composite could be considered as one of the future penetrator materials.
논문 : 분말야금 ; 고속 충돌된 텅스텐 중합금의 미세조직 변화
김은표 ( Eun Pyo Kim ),송흥섭 ( Heung Sub Song ),문인형 ( In Hyung Moon ) 대한금속재료학회 ( 구 대한금속학회 ) 1998 대한금속·재료학회지 Vol.36 No.6
Microstructural change in 93W-4.9Ni-2.1Fe heavy alloy was investigated by metallurgical analyses of the fragments from penetrators after high speed impact test. Two kinds of specimens were prepared. The one was normal specimen manufactured by a typical liquid phase sintering process, and the other was the D specimen made by a double-cycle sintering process, respectively. The morphology of tungsten grain in the D specimen became irregular by the double-cycle sintering. And microstructural changes observed from the fragments after the test were local deformation in W grain and matrix phase, fracture, formation of adiabatic shear band, reaction with steel target and so on, irrespective of the specimens. However, fracture mode was changed from W-W and W-matrix interface to W cleavage when W grains became irregular, by which the penetrator could be more brittle and fragile. From the analyses, it was suggested that the microstructural change in tungsten grain and formation of inhomogeneous matrix band would be beneficial for the self sharpening effect.
역탄도 기법을 이용한 탄소섬유/열경화성수지 복합재 그루브의 파단 특성 연구
최재호 ( Jae Ho Choi ),박인서 ( In Seo Park ),송흥섭 ( Heung Sub Song ),박관진 ( Kwan Jin Park ) 한국복합재료학회 2004 Composites research Vol.17 No.2
나사산을 가지는 구조재료는 높은 전단 응력을 한 방향으로 전달해 주는 용도로 많이 사용되며, 이를 응용하여 고속의 충격에너지나 전단하중에 견딜 수 있는 기어 모양의 부품 등 항공 및 군수용 재료에 적용되어왔다. 최근에는 재료를 보다 경량화 하려는 노력의 일환으로 기존의 금속재료를 섬유강화 고분자 수지계 복합재료로 대체하기 위한 연구가 활발히 진행되고 있다. 본 연구에서는 탄소섬유/열경화성 수지계 복합재를 사용하여 나사산(groove)을 가지는 시편을 제작한 뒤 역탄도 기법으로 고속변형 특성 평가를 실시하였고, 이를 통하여 군수용 부품 재료로의 적용 가능성을 타진해 보았다. It is a primary object of the present study to test and evaluate the shear load carrying capability of a carbon fiber reinforced thermosets composite structure with buttress grooves for military applications. The buttress form of groove is an effective structure in any applications where high shear loads are transferred in one direction between structural components. Inverse ballistics methodology was introduced to investigate the high strain rate properties of composite groove specimens. In comparison with the conventional methods, inverse ballistics technique is a proper one under dynamic environment.
논문 : 기계적 성질 ; 텅스텐 중합금의 미세조직과 동적 변형거동의 상관관계 연구
김동국 ( Dong Kuk Kim ),이성학 ( Sung Hak Lee ),송흥섭 ( Heung Sub Song ) 대한금속재료학회 ( 구 대한금속학회 ) 1998 대한금속·재료학회지 Vol.36 No.6
Correlation of microstructure and fracture mode with the dynamic torsional behavior was investigated on tungsten heavy alloys whose size and shape were changed using the sintering conditions such as sintering temperature, time, and cycle. Dynamic torsional tests were conducted for seven specimens, four of which were fabricated by the repeated sintering process, using torsional Kolsk bar, and then the test data were compared via microstructures, mechanical properties, adiabatic shear banding, and fracture mode. With increasing the sintering temperature and time, the size of tungsten particles was increased, and their hardness became higher, thereby deteriorating fracture toughness. The dynamic torsional test results indicated that in the specimens whose tungsten particles were coarse and irregular-shaped, cleavage fracture occurred in the center of the gage section with little shear deformation, whereas shear deformation was concentrated into the center of the gage section in the conventionally processed specimens. The deformation and fracture behavior of the specimens having coarse tungsten particles correlated well with the observation of the impacted penetrator specimens and the in situ fracture test results. i.e., microcrack initiation at coarse tungsten particles and cleavage crack propagation through tungsten particles. These findings suggested that there would be optimum tungsten particle size since the cleavage fracture mode would be beneficial for the self-sharpening.
High Energy Ball Mill에 의해 제조된 75w-25Cu 의 치밀화 거동에 관한 연구
이성,송흥섭,노준웅,홍문희,김근표,김용우 대한금속재료학회(대한금속학회) 1993 대한금속·재료학회지 Vol.31 No.2
Solid and liquid phase sintering behaviors of ball-milled 75W-25Cu have been studied by using a dilatometry technique. The ball-milled 75W-25Cu was prepared by high energetic ball milling under argon atmosphere of 1 atm with duration times of 50 to 400 hrs. The sintering was performed in the dilatometer under flowing hydrogen atmosphere with a heating rate of 3℃/min. To compare with the ball milled 75W-25Cu, blended 75W-25Cu was also prepared and sintered. Sintering shrinkage, dl/1, increased with increasing milling time from 50 to 400 hrs. The shrinkage versus temperature plots of the ball-milled 75W-25Cu can be divided into three regions, while for that of the blended 75W-25Cu two regions. The characteristics of ball-milled 75W-25Cu were analyzed by energy dispersive spectroscopy (EDS), differential scanning calorimeter(DSC) and scanning electron microscopy (SEM). The considerable grain growth of W particles was observed during the liquid phase sintering of the ball-milled 75W-25Cu. From these results, the solid and liquid phase sintering behaviors were discussed in terms of the size, the stored energy, and the distribution of W and Cu particles embedded in the ball-milled 75W-25Cu composite powders. (Received August 18, 1992)
W-Ni-Fe 중합금에서 바인더 조성에 따른 미세조직 및 기계적 성질의 변화
이성,백운형,김은표,송흥섭,노준웅,천길성 대한금속재료학회(대한금속학회) 1992 대한금속·재료학회지 Vol.30 No.8
W heavy alloys with different composition of matrix were sintered at various temperatures to investigate the microstructure and mechanical properties. The Ni/Fe ratios in the composition of 93W-7 (Ni-Fe) heavy alloys were varied from 7/3 via 8/2 to 9/1 by weight. The results showed that, with increased in Ni contents, the volume fraction of matrix was increased due to increased solubility of W in the matrix. In trun, it lowered dihedral angle and facilitated matrix peneratration along the grains to lower contiguity. The increased volume fraction of ductile matrix and decreased contiguity contributed to a higher ductility and toughness. The specimen with 9/1 of Ni/Fe ratio showed the lowest impact energy even though it had the largest volume fraction of matrix and the lowest contiguity. This was attributed to the highly dissolved W in the matrix. The optimum composition in the matrix is 80% Ni and 20Fe.