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열분석법에 의한 Al-2,1Li-2.9Cu합금의 석출현상에 미치는 In 첨가의 영향
박태원,송영범,이용윤 ( Tae Won Park,young Beum Song,Yong Yun Lee ) 한국열처리공학회 1997 熱處理工學會誌 Vol.10 No.4
A study was conducted to examine the effects of In addition on the precipitation behaviors of Al-2.1Li-2.9Cu alloy by differential scanning calorimetry, transmission electron microscopy and microhardness tester. DSC analysis was measured over the temperature range of 25∼50℃ at a heating rate of 2∼20℃/min. The heat evolution peaks due to the formation of GP zone and δ` phase shift to higher temperature and the peaks to T₁and θ` phases shift to lower temperature by In addition. From this result, it was proved that the formation of GP zone and δ` phase is suppresed whereas that of T₁and θ` phases are accelerated by the In addition of 0.15wt%. The age hardening curve aged at 190℃ showed that the In bearing alloy(alloy B) has more faster age hardening response and a higher peak hardness than In-free alloy(alloy A), attributed to the fine and homogeneous distribution of T₁and θ` phases. The activation energies for the formation of δ`phase in In-free and In-bearing alloys are 22.3㎉/㏖ and 18.6㎉/㏖, respectively. Those for T₁(+θ`) phase of In-free and In-bearing alloys are 24.3 and 37.5㎉/㏖, respectively. Quenched-in excess vacancies play an important role to the formation of precipitates.
박태원,송영범,김진영,양성호,박철규,서준석,김희진,Park, Tae-Won,Song, Young-Beum,Kim, Jin-Young,Yang, Sung-Ho,Park, Chul-Gyu,Seo, Jun-Suck,Kim, Hee-Jin 대한용접접합학회 2010 대한용접·접합학회지 Vol.28 No.6
The pre-heat free consumables for GMAW, SAW and FCAW processes that matche with the Cu-bearing PFS-700 steel which has yield strength over 700MPa were developed and evaluated to see the suitability in military such as submarine and battle ship. Explosion Bulge Test underwater was developed and applied to see the reliability of welded structure. All welding was conducted without pre-heat before welding, the interpass temperature was below $150^{\circ}C$ for all welding conditions. Tensile strength for the weld metal in GMAW, SAW and FCAW process is 887MPa, 875MPa and 813MPa, respectively, these values are similar to the base metal of PFS-700 steel of 838MPa. EBT results in GMAW, SAW and FCAW show 14.0%, 14.02% and 15.9% reduction of thickness without generation of crack, respectively and stand-off distance was set up properly to have over 14.0% reduction of thickness. Through EBT results, the developed new consumables are applicable to the weapon systems such as submarine and battle ship.
800 MPa급 무예열 용접재료의 폭파변형성능에 관한 연구
박태원,송영범,김진영,박철규,김희진,Park, Tae-Won,Song, Young-Beum,Kim, Jin-Young,Park, Chul-Gyu,Kim, Hee-Jin 대한용접접합학회 2009 대한용접·접합학회지 Vol.27 No.6
The Cu-bearing PFS-700 steel which has yield strength over 700 MPa was developed to replace the existing submarine structural material, HY-100. The PFS-700 steel has a combination of good mechanical properties and superior weldability. Becaus of that, it can be welded without pre-heating. The application of PFS-700 steel to submarine or battle ship will give a great reduction of cost by omitting pre-heating or lowering pre-heat temperature. To develop pre-heating free welding consumables that match and take advantage of PFS-700 steel, new welding consumables have been designed for the GMAW, SAW processes and explosion bulge test(EBT) was conducted to see the reliability of welded structure. All welds were made without pre-heating, and the inter-pass temperature was below $50^{\circ}C$ for SAW50 and $150^{\circ}C$ for GMAW and SAW150. All EBT specimens show over 14% thickness reduction without through-thickness crack or crack propagation to the hole-down area. Tensile properties for all welding conditions show higher(GMAW) or similar values(SAW50, SAW150) to the base metal. Charpy impact values for the weld metal also show 163.5J(GMAW), 95.4J(SAW50) and 69.0J(SAW150), which meet the goal(higher than 50J) of this project.
템퍼링 온도에 따른 ARMOX 500T 장갑재의 미세조직과 기계적 특성
임현석,이지민,송영범,김홍규,황병철,Lim, Hyeon-Seok,Lee, Jimin,Song, Young-Beum,Kim, Hong-Kyu,Hwang, Byoungchul 한국재료학회 2017 한국재료학회지 Vol.27 No.7
The resistance of metallic materials to ballistic penetration generally depends on a number of parameters related to projectile, impact, and armor plate. Recently, armor materials have been required to have various properties such as hardness, strength, and impact toughness in order to maintain an excellent ballistic resistance even after impact. In the present study, the influence of tempering on the microstructure and mechanical properties of an ARMOX 500T armor steel plate was investigated and then compared with those of S45C and SCM440 steels. As the tempering temperature increased, the hardness and strength gradually decreased, whereas the ductility and impact toughness clearly increased because the hardness, tensile, and impact properties were affected by the microstructural evolution and precipitation occurring during tempering. On the other hand, temper embrittlement appeared at tempering temperatures of 300 to $400^{\circ}C$ for the impact specimens tested at low temperature.
이지민,한종주,송영범,함진희,김홍규,황병철,Lee, Ji-Min,Han, Jong-Ju,Song, Young-Beum,Ham, Jin-Hee,Kim, Hong-Kyu,Hwang, Byoungchul 한국재료학회 2018 한국재료학회지 Vol.28 No.8
This paper presents a study of the microstructure and mechanical properties of commercial high-hardness armor (HHA) steels tempered at different temperatures. Although the as-received specimens of all the steels exhibit a tempered martensite structure with lath type morphology, the A steel, which has the smallest carbon content, had the lowest hardness due to reduced solid solution hardening and larger lath thickness, irrespective of tempering conditions. As the tempering temperature increases, the hardness of the steels steadily decreases because dislocation density decreases and the lath thickness of martensite increases due to recovery and over-aging effects. When the variations in hardness plotted as a function of tempering temperature are compared with the hardness of the as-received specimens, it seems that the B steel, which has the highest yield and tensile strengths, is fabricated by quenching, while the other steels are fabricated by quenching and tempering. On the other hand, the impact properties of the steels are affected by specimen orientation and test temperature as well as microstructure. Based on these results, the effect of tempering on the microstructure and mechanical properties of commercial high-hardness armor steels is discussed.
박종수 ( Jong Soo Park ),송영범 ( Young Beum Song ),임태홍 ( Tae Hong Lim ),홍성석 ( Sung Suk Hong ),이흥렬 ( Hung Reyl Lee ),심인옥 ( In Ok Shim ) 대한금속재료학회 ( 구 대한금속학회 ) 2006 재료마당 Vol.19 No.5
앞에서 언급되어진 Titanium 합금 빌렛에서의 결함종류, 원인 분석 및 해결방안을 표2에 요약하였다.
Fe-20%Mn 마르텐사이트 합금의 기계적 성질에 미치는 변형량 및 변형속도의 영향
김원백,최종술,박홍래,송영범 대한금속재료학회(대한금속학회) 1995 대한금속·재료학회지 Vol.33 No.9
The effects of compressive strain and strain rate on the strain-induced martensitic transformation and mechanical properties of Fe-20%Mn alloy were investigated. At low strain rates of 2×10^(-3)/sec and 2x10^(-1)/sec, the amounts of ε and α′ martensite increased with strain at the expense of γ. The increase was the largest at low strains up to 8%. At the highest strain rate of 6x10³/sec, the amount of retained γ increased due probably to the stabilization of γ by adiabatic heating during testing. The alloy showed high strain hardening especially in low strain range where most of the strain induced transformation occurred. The strain rate did not have an effect on strength when strain rates were low. When the strain rate increased to 6×10³/sec, the true stress increased at all strain levels. However, high strain rate did not increase the hardness. It seems that during a dynamic compression test an additional strengthening mechanism may work to increase the true stress. We believe that the dislocation drag effect may be responsible far the increase in stress during the high-rate compression test.