• 제목/요약/키워드: aluminum 7075-T6

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Al 7075의 마찰교반 용접부 미세조직에 관한 연구 (Microstructures in friction-stir welded Al 7075-T651 alloy)

  • 장석기;이돈출;김성종;전정일
    • 한국마린엔지니어링학회:학술대회논문집
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    • 한국마린엔지니어링학회 2005년도 전기학술대회논문집
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    • pp.331-338
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    • 2005
  • The grain structure, dislocation density and second phase particles in various regions including the stir zone(SZ), thermo-mechanically affected zone(TMAZ), and heat affected zone(HAZ) of a friction stir weld 6.35mm thick aluminum 7075-T651 alloy were investigated and compared with the base metal. The microstruectures of nugget zone were compared according to tool rotation speeds and tool transition speeds. The hardness profiles of nugget zone were increased, while decreasing rotation speed and increasing welding speed. The optimal microstructure was gained at the low rotation speed 800rpm and th high welding speed 124mm/min. The nugget microstructures of fracture surface, transgranular dimple and quasicleavage type were showed different fracture type with the HAZ, shear fracture type.

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이종알루미늄합금 FSW 접합부의 피로균열진전 특성 (Fatigue Crack Growth Properties of Friction Stir Welded Dissimilar Aluminum Alloys)

  • 이원준;이효재;김형진;박원조
    • 한국해양공학회지
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    • 제27권1호
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    • pp.37-42
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    • 2013
  • The presence of a crack can increase the local stress or strain, which can cause inelastic deformation and significantly reduce the life of a component or structure. Therefore, in this study, the fatigue crack growth (FCG) behaviors of friction stir welded Al 2024-T3 and Al 7075-T6 specimens were examined, with fatigue cracks growing parallel to the dynamically recrystallized zone at variable ${\Delta}K$ values and an R ratio of 0.3. In addition, the FCG values of the base metal Al 2024-T3 and Al 7075-T6 were tested under the same conditions and parameters as comparative groups. The results showed that compared with the base metal Al 2024 specimen, which had the best fatigue property, the welded specimen had only 88% of the fatigue cycles.

7075-T6 A1 합금의 피로균열진전의 변동성에 대한 확률론적 해석 (A Stochastic Analysis of Variation in Fatigue Crack Growth of 7075-T6 Al alloy)

  • 김정규;심동석
    • 대한기계학회논문집A
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    • 제20권7호
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    • pp.2159-2166
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    • 1996
  • The stochastic properties of variation in fatigue crack growth are important in reliability and stability of structures. In this study,the stochastic model for the variation of fatigue crack growth rate was proposed in consideration of nonhomogeneity of materials. For this model, experiments were ocnducted on 7075-T6 aluminum alloy under the constant stress intensity factor range. The variation of fatigue crack growth rate was expressed by random variables Z and r based on the variation of material coefficients C and m in the paris-Erodogan's equation. The distribution of fatigue life with respect to the stress intensity factor range was evaluated by the stochastic Markov chain model based on the Paris-Erdogan's equation. The merit of proposed model is that only a small number of test are required to determine this this function, and fatigue crack growth life is easily predicted at the given stress intensity factor range.

7XXX계 단조재의 피로 및 파괴인성에 미치는 제조공정의 영향 (Effect of Fabrication Processes on the Fatigue and Fracture Toughness of 7XXX Series Aluminum Forgings)

  • 이오연;임재규;송기홍;손영일;은일상;신돈수
    • 열처리공학회지
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    • 제9권3호
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    • pp.161-168
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    • 1996
  • The purpose of this study is to investigate the effect of impurity level and fabrication processes on the strength, fracture toughness and fatigue resistance of 7075, 7050 and 7175 high strength aluminum forgings. It has been verified that plane strain fracture toughness and fatigue characteristics of a specially processed 7175S-T74 alloy is superior to a conventionally processed 7075-T6/T73, 7050-T74 and 7175-T74 alloys. These beneficial effects primarily arise from two view points, i.e., the effect of reducing the impurity level of iron and silicon has significantly diminished the size and volume fraction of second phase particles such as $Al_7Cu_2Fe$ and $Mg_2Si$. Futher reduction of the amount of nonequilibrium second phase particles has been observed by applying a special fabrication process.

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Al 7075의 마찰교반 용접부 특성에 관한 연구 (Weldability of Al 7075 Alloy according to different tools and welding conditions by F.S.W)

  • 장석기;전정일
    • 한국마린엔지니어링학회:학술대회논문집
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    • 한국마린엔지니어링학회 2005년도 전기학술대회논문집
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    • pp.348-358
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    • 2005
  • This paper showed mechanical properties and behaviors of macrostructures for specimens welded by F.S.W according to welding conditions and tool with 6.35$mm_t$ aluminum 7075-T651alloy plate. It resulted in defect-free weld zone in case tool rotation speed was 800rpm, 1250rpm and 1600rpm respectively that transition speed was changed to 15mm/min, 61mm/min and 124mm/min with tool's pin diameter 4${\Phi}$mm and 6${\Phi}$mm. The optimum mechanical property, ultimate stress,${\sigma}_Y$=470Mpa was obtained at the condition of 124mm/min of travel speed with 800rpm of tool rotation speed using full screw type pin, shoulder dia. 20${\Phi}$mm, pin dia.6${\Phi}$mm and pin length 6mm. The full-screw type and the half-screw type pin showed the similar behaviors of weldability. It is found that the size of nugget was depended on tool transition speed and tool dimension by macrostructures of the cross section of weld zone.

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Al 7075의 마찰교반 용접부 특성에 관한 연구 (Weldability of Al 7075 Alloy according to different tools and welding conditions by F.S.W)

  • 장석기;전정일
    • Journal of Advanced Marine Engineering and Technology
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    • 제30권1호
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    • pp.30-41
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    • 2006
  • This paper shows mechanical Properties and behaviors of macrostructures for specimens welded by F.S.W according to welding conditions and tool dimensions with $6.35mm_t$ aluminum 7075-T651 alloy plate. It apparently results in defect-free weld zone in case transition speed was changed to 15mm/min 61mm/min and 124mm/min under conditions of tool rotation speed such as 800rpm. 1250rpm and 1600rpm respectively with tool's Pin diameter 40mm and 60mm. The optimum mechanical property, ultimate stress,${\sigma}_Y=470Mpa$ is obtained at the condition of 124mm/min of travel speed with 800rpm of tool rotation speed using full screw type pin. shoulder dia. $20{\phi}mm$ pin dia. $6{\phi}mm$ and pin length 6mm. The full-screw type and the half-screw type pin shows the similar behaviors of weldability. It is found that the size of nugget is depended on tool transition speed and tool dimension by macrostructures of the cross section of weld zone.

Out-of-plane ductile failure of notch: Evaluation of Equivalent Material Concept

  • Torabi, A.R.;Saboori, Behnam;Kamjoo, M.R.
    • Structural Engineering and Mechanics
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    • 제75권5호
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    • pp.559-569
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    • 2020
  • In the present study, the fracture toughness of U-shaped notches made of aluminum alloy Al7075-T6 under combined tension/out-of-plane shear loading conditions (mixed mode I/III) is studied by theoretical and experimental methods. In the experimental part, U-notched test samples are loaded using a previously developed fixture under mixed mode I/III loading and their load-carrying capacity (LCC) is measured. Then, due to the presence of considerable plasticity in the notch vicinity at crack initiation instance, using the Equivalent Material Concept (EMC) and with the help of the point stress (PS) and mean stress (MS) brittle failure criteria, the LCC of the tested samples is predicted theoretically. The EMC equates a ductile material with a virtual brittle material in order to avoid performing elastic-plastic analysis. Because of the very good match between the EMC-PS and EMC-MS combined criteria with the experimental results, the use of the combination of the criteria with EMC is recommended for designing U-notched aluminum plates in engineering structures. Meanwhile, because of nearly the same accuracy of the two criteria and the simplicity of the PS criterion relations, the use of EMC-PS failure model in design of notched Al7075-T6 components is superior to the EMC-MS criterion.

일방향 탄소섬유/에폭시 복합재 패치로 보수된 알루미늄의 피로특성에 대한 연구 (A Study on the Fatigue Characteristics of Aluminum Repaired by Unidirectional Graphite/Epoxy Composites)

  • 김만태;신명근;한운용;이지훈;이경엽
    • 한국정밀공학회:학술대회논문집
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    • 한국정밀공학회 2003년도 춘계학술대회 논문집
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    • pp.1386-1388
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    • 2003
  • In this study. the fatigue behavior of cracked aluminum repaired by unidirectional graphite/epoxy composites was experimentally investigated. The aluminum used was 7075-T6 and the patch used was four plied unidirectional ([0]$_4$) composites. The composite patch was adhesively bonded to the cracked aluminum using secondary bonding procedure. Two different specimens of cracked aluminum and cracked aluminum repaired with patch were used in the fatigue tests. Load ratio and the frequency applied in the fatigue tests were 0 and 10 Hz, respectively. The results showed that the fatigue behavior of cracked aluminum was improved by repairing the cracked area with composite patch. Specifically, the specimen repaired by composite patch showed 30% more improved fatigue behavior than regular specimen.

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상용 알루미늄 합금의 고속 인장/압축 변형거동 규명 (Dynamic deformation behavior of aluminum alloys under high strain rate compressive/tensile loading)

  • 이억섭;김관희;김면수;황시원
    • 대한기계학회:학술대회논문집
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    • 대한기계학회 2000년도 추계학술대회논문집A
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    • pp.268-273
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    • 2000
  • Mechanical properties of the materials used for transportations and industrial machinery under high strain rate loading conditions are required to provide appropriate safety assessment to these mechanical structures. The Split Hopkinson Pressure Bar(SHPB) technique, a special experimental apparatus, can be used to obtain the material behavior under high strain rate loading condition. In this paper, dynamic deformation behaviors of the aluminum alloys, Al2024-T4, Al6061-T6 and Al7075-T6, under high strain rate compressive and tensile loading are determined using SHPB technique.

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알루미늄 합금재의 피로크랙 전파거동에 미치는 미소원공결함 (The Influence of the Small Circular Hole Defect on the Fatigue Crack Propagation Behavior in Aluminum Alloys)

  • 김건호;이호연
    • Journal of Advanced Marine Engineering and Technology
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    • 제32권6호
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    • pp.834-840
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    • 2008
  • We carried out fatigue testing with materials of aluminum alloyC7075-T6, 2024-T4) by rotary bending fatigue tester. We investigated fatigue limit, fatigue crack initiation, fatigue crack propagation behavior and possibility of fatigue life prediction to the different small circular hole defect. The summarized result are as follows; Fatigue limit of the smooth specimens were related tensile strength and yield strength. In case of more large applied stress and small circular hole crack defect, the fatigue crack was grown rapidly. The fatigue crack propagation behavior proceed at according to inclusion. Fatigue crack propagation ratio appeared instability and retardation phenomenon in the first half of fatigue life but appeared stability and replied in the latter half. On other hand, this experimental data of the materials are appeared fatigue life predictability.