• Title/Summary/Keyword: Charpy V-notch test

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Failure Behaviors Depending on the Notch Location of the Impact Test Specimens on the HAZ (용접열영향부 충격시험편 노치 위치에 따른 파괴거동)

  • Jang, Yun-Chan;Hong, Jae-Keun;Park, Ji-Hong;Kim, Dong-Wook;Lee, Young-Seog
    • Proceedings of the KSME Conference
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    • 2007.05a
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    • pp.706-711
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    • 2007
  • Numerical studies were performed to examine the effects of notch location of impact specimens on the failure behavior of HAZ (heat affected zone) when Charpy V-notch impact test were made at a low temperature ($1^{\circ}C$). Carbon steel plate (SA-516 Gr. 70) with thickness of 25mm for pressure vessel was welded by SMAW (shielded metal-arc welding) and specimens were fabricated from the welded plate. Charpy tests were then performed with specimens having different notch positions of specimens varying from the fusion line through HAZ to base metal. A series of finite element analysis which simulates the Charpy test and crack propagation initiating at the tip of V-notch was carried out as well. The finite element analysis takes into account the irregular fusion line and non-homogenous material properties due to the notch location of the specimen in HAZ. Results reveals that the energies absorbed during impact test depend significantly on the notch location and direction of specimen. Finite element analysis also demonstrates that the notch location of specimens, to a great extent, influences the reliability and consistency of the test.

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A Study on the Correlation between Advanced Small Punch Test and Charpy V-notch Test on X20CrMoV121 and 2.25Cr1Mo steels Weldment (X20CrMoV121강과 2.25Cr1Mo강 용접부의 ASP 시험과 CVN 충격 시험의 상관관계에 대한 연구)

  • Lee, Dong-Hwan;Kim, Hyoung-Sup
    • Journal of Welding and Joining
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    • v.26 no.3
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    • pp.37-44
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    • 2008
  • Charpy V-Notch test is commonly used to evaluate fracture toughness. However, since the region to be evaluated is limited to bulk material due to the specimen size required, individual evaluation of micro-structures on weldment is very difficult. In this study, ASP(Advanced Small Punch) test was carried out to evaluate material degradation and fracture toughness on the B.M, W.M and each micro-structures of HAZ for X20CrMoV121 and 2.25Cr1Mo steels with artificial aging time. In addition, to evaluate fracture toughness and material degradation of B.M and W.M of X20CrMoV121 steels with aging times, CVN (Charpy V-notch) test was performed. And then the correlation between ASP and CVN test on X20CrMoV121 steels was obtained. Furthermore, through this correlation, material degradation property of each micro-region of the HAZ in weldment, which was impossible to be evaluated by the CVN test, can be estimated and determined.

A study on the correlation between V charpy absorbed energy and critical COD value in the welded parts of high tensil strength steel under various welding methods (고장력강 용접부에 있어서 한계 COD값과 V charpy충격치와의 상관성에 관한 연구)

  • 김영식;김충해
    • Journal of Advanced Marine Engineering and Technology
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    • v.12 no.3
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    • pp.57-67
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    • 1988
  • Although handicapped by the inability to bridge the size gap between small laboratory sample and large engineering component, the V charpy test sample method does possess certain advantages, such as each of preparation, simplicity of test method, speed, low cost in test machinery, and low cost per test. On the other hand, the COD test method does posses advantages, which reduce the size gap between the laboratory sample and actual engineering component. Consequently, the correlation between V charpy absorbed energy and the critical COD value is required for estimating critical COD value from the simple V charpy test results. In this paper, the high tensile strength steel AH36 plate specimens having a single edge cracked notch were investigated to find out the correlation between V charpy absorbed energy and critical COD value in the welded parts under such various welding methods as shielded metal arc welding, the submerged arc welding and the electro gas welding by means of V charpy impact test and static 3-point bending test. Main results obtained are as follow ; 1. The relationships between V charpy absorbed energy Wc' and critical COD value ($\delta_c$)show; $\delta_c$=0.0065 Wc'+0.1906. 2. Ductile- brittle transition behaviours can be estimated by means of fracture appearance and general yielding behaviours. 3. The V charpy absorbed energy of SMAW is higher than that of SAW, EGW and similar relationships are obtained in the COD tests.

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HAZ TOUGHNESS AND MICROSTRUCTURE IN HIGH NITROGEN AUSTENITIC STAINLESS STEEL

  • Sato, Yoshihiro;Shiotsu, Tomoya;Nakagawa, Takafumi;Kikuchi, Yasushi
    • Proceedings of the KWS Conference
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    • 2002.10a
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    • pp.38-42
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    • 2002
  • HAZ(Heat Affected Zone of weldm ents) properties were investigated for a high nitrogen austenitic stainless steel with a chemical composition of Fe-0.02C-0.15Si-6.00Mn-10.0Ni-23.0Cr-2.00Mo-0.48N-0.14V. Thermal cycle of HAZ was simulated by the thermal cycle simulator (Gleeble 1500). The heat treatment was applied to the Charpy test size sample without notch under various peak temperatures and/or the holding times condition. V-notch Charpy test was performed at the temperature range of 273~77 K. Metallographic examination also was carried out by using optical microscopy, scanning electron microscopy and transmission electron microscopy. The simulated specimens revealed a slight embrittlement compared with the base materials. The impact toughness of the specimens deteriorated with the decreasing test temperature. The results from Charpy V-notch test, however, showed that significant degradation of absorbed energy caused by brittle fracture was not observed for the specimen tested in the test temperature range.

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Fracture Mechanical Study on the Charpy V-notch and Fatigue Crack Propagation 8ehavior of Rail Steels (레일강의 샬피거동 및 피로균열 성장거동에 관한 파괴역학적 고찰)

  • Kim, Sung Hoon
    • KSCE Journal of Civil and Environmental Engineering Research
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    • v.14 no.6
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    • pp.1319-1327
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    • 1994
  • Since fatigue cracks in rail can be the source of fractures and subsequent derailments, quantitative evaluation of the fatigue behavior and fracture properities due to the analysis results of laboratory test are drawn on the basis for predicting fatigue life and making a decision of safe inspection interval. Charpy V-notch and fracture toughness behavior were evaluated from the results of Charpy impact test. Fatigue test was performed by using CT type specimen under constant amplitude loading, and finally the effects of the following parameters; crack orientation, temperature, and stress ratio, on the fatigue crack growth behavior were studied.

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Irradiation Behavior of Reactor Pressure Vessel SA508 class 3 Steel Weld Metals (압력용기강재 SA508 class 3 용착금속의 조사거동)

  • Koh, Jin-Hyun;Park, Hyoung-Keun;Kim, Soo-Sung;Hwang, Yong-Hwa;Seo, Yun-Seok
    • Journal of Welding and Joining
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    • v.28 no.5
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    • pp.69-74
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    • 2010
  • Irradiation behavior of the reactor pressure vessel SA508 class 3 steel weld metals was examined by Charpy V Notch impact specimens. The specimens were exposed to a fluence of $2.8{\times}1019$ neutrons(n)/$cm^2$(E>1 MeV) at $288^{\circ}C$. The irradiation damage of weld metal was evaluated by comparison between unirradiated and irradiated specimens in terms of absorbed energy and lateral expansion. The specimens for neutron irradiation were welded by submerged arc welding process at a heat input of 3.2 kJ/mm which showed good toughness in terms of weld microstructure, absorbed energy and lateral expansion. The post-irradiation Charpy V notch 41J and 68J transition temperature elevation were $65^{\circ}C$ and $70^{\circ}C$, respectively. This elevation was accompanied by a 20% reduction in Charpy V notch upper shelf energy level. The lateral expansion at 0.9mm irradiated Charpy specimens showed temperature elevation of $65^{\circ}C$ and was greatly decreased due to radiation damage.

FRACTURE TOUGHNESS CHARACTERISTICS IN HIGH ENERGY DENSITY BEAM WELDED JOINT OF HIGH TENSILE STEELS

  • Ro, Chan-Seung;Yamada, Tomoaki;Mochizuki, Masahito;Ishikawa, Nobuyuki;Bang, Han-Sur;Toyoda, Masao
    • Proceedings of the KWS Conference
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    • 2002.10a
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    • pp.583-588
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    • 2002
  • The purpose of the study is to evaluate fracture toughness on the Laser and the electron beam welded joints of high tensile steels (HT500, HT550, HT650) by using 3-point bend CTOD and Charpy impact test. WM (weld metal) CTOD tests have been carried out using two kinds of CTOD specimen, the Laser beam welding (108mm length, and 24mm width, and 12mm thickness) and the electron beam welding (l71mm length, and 38mm width, and 19mm thickness). WM Charpy impact specimen is a standard V-notch type, and the temperature of the experiment is changed from -45 to 20 degree of centigrade. FE-analysis is also performed in order to investigate the effect of stress-strain fields on fracture characteristics. Results of the standard V-notch Charpy test are influenced by strength mis-match effect and the absorbed energy vE depends on crack path, and The transition temperature of Laser beam welded joints is more higher than that of electron beam welded joints. Results of the 3-point bend test give low critical CTOD and the crack path is in the weld metal of al specimens. These results indicate fracture toughness characteristics of the welded joints and transition temperature of HT500 are similar both a Laser beam welded joint and an electron beam welded joint. But the fracture toughness and the transition temperature of the electron beam welded joints of HT550 and HT650 are higher than those o the Laser beam welded joints.

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Evaluation of Reheat Cracking Susceptibility with Simulated Heat Affected Zones in Cr-Mo-V Turbine Rotor Steel (CrMoV 터빈로터강에서 모의 열영향부 시험편을 이용한 재열균열 민감도평가)

  • 김광수
    • Journal of Welding and Joining
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    • v.13 no.1
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    • pp.89-102
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    • 1995
  • The evaluation of reheat cracking susceptibility in CrMoV turbine rotor steel was performed using thermally simulated heat affected zones. The examinations were carried out in terms of microstructural characterization, microhardness measurement and a Charpy type notch opening three point bend test. It was found that reheat cracking susceptibility increased as the peak temperature increased. This effect was due to the combined effects of the carbide dissolution and unrestricted grain growth at 1350.deg. C peak temperature. Reheat cracking susceptibility was estimated based on microhardness measurement and prior austenite grain size. It was established that for this particular material, reheat cracking in coarse grained heat affected zone can be eliminated if the microhardness is below about 360DPH and the grain size is below about 30.mu.m. It is evident that reheat cracking susceptibility can be eliminated or reduced by carefully controlling the welding parameters such that a refined structure is produced in the coarse grained heat affected zone.

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Instrumented Impact Test using Subsize Charpy Specimen for Evaluating Impact Fracture Behavior in Bulk Amorphous Metals (벌크 아몰퍼스 금속의 충격파괴 거동 평가를 위한 미소 샬피 시험편을 사용한 계장화 충격 시험법)

  • Shin, Hyung-Seop;Ko, Dong-Kyun;Jung, Young-Jin;Oh, Sang-Yeob;Kim, Moon-Saeng
    • Proceedings of the KSME Conference
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    • 2003.04a
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    • pp.101-106
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    • 2003
  • In order to investigate the mechanical behavior of newly developed materials, the evaluation of mechanical properties using small-size specimen is essential. For those purposes, an instrumented impact testing apparatus, which provides the load-displacement curve under impact loading without oscillations, was devised. To develop the test procedure with the setup, the impact behaviors of various kinds of structural materials such as S45C, SCM4, Ti alloys (Ti-6V-4Al) and Zr-based bulk amorphous metal, were investigated through the instrumented Charpy V-notch impact tests. The calibrations of the dynamic load and displacement that was calculated based on the Newton' second law were carried out through the quasi-static load test and the comparison of a directly measured value using a laser displacement meter. Satisfactory results could be obtained. The crack initiation and propagation processes during impact fracture could be well divided on the curve, depending on the intrinsic characteristic of specimen tested; ductile or brittle. The absorbed impact energy in Zr-basd BAM was largely used for crack initiation not for crack propagation process. The fracture surfaces under impact loading showed different feature when compared with the static cases.

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Failure Analysis and Weibull Statistical Analysis according to Impact Test of the Angular Pin for Injection Molding Machines (사출금형기계용 앵귤러핀의 충격시험에 따른 파손분석과 와이블 통계 해석)

  • Kim, Cheol-Su;Nam, Ki-Woo;Ahn, Seok-Hwan
    • 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.