• Title/Summary/Keyword: Charpy impact value

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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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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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Impact behavior on temperature effect of nano composite materials (온도변화에 따른 나노 복합재료의 충격거동)

  • KIM, Hyung-Jin;LEE, Jung-Kyu;KOH, Sung Wi
    • Journal of the Korean Society of Fisheries and Ocean Technology
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    • v.51 no.4
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    • pp.561-566
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    • 2015
  • In this study, the effect of temperature effect of the rubber matrix filled with nano sized silica particles composites with silica volume fraction of 19-25% was investigated by the Charpy impact test. The Charpy impact test was conducted in the temperature range from $-40^{\circ}C$ to $0^{\circ}C$. The critical energy release rate GIC of the rubber matrix composites filled with nano sized silica particles was considerably affected by temperature and it was shown that the maximum value was appeared at higher temperature between temperature tested and it was shown that the value of GIC increases as temperature tested increases. The major fracture mechanisms were matrix deformation, silica particle debonding and delamination, microcrack between particles and matrix, and/or pull out between particles and matrix which is ascertained by SEM photographs of Charpy impact surfaces fracture.

Evaluation of Fracture Toughness of Pressure Vessel Steel Using Charpy Impact Test Specimens (Charpy 충격시편을 이용한 압력용기 재료의 파괴인성 측정)

  • Han, Dae-June;Park, Sun-Pil
    • Nuclear Engineering and Technology
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    • v.19 no.1
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    • pp.1-9
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    • 1987
  • The fracture toughness of SA 533 Grade B Class 1 steel has been studied with the Charpy impact test specimens in a range of temperature between -4$0^{\circ}C$ and 288$^{\circ}C$. The dynamic fracture toughness is measured by the instrumented precracked Charpy impact test while the static fracture toughness is by the 3-point bend test based on the unloading compliance method. The results are compared with the data obtained from the large specimens. It is known through the studies that temperature dependence of the appropriate (a low bound) value of the fracture toughness can be estimated by taking the static fracture toughness above the transition temperature and the dynamic fracture toughness below the temperature and it is also shown that the tests are satisfied with the requirements of ASTM E 813 when the side-groove is more than 14%.

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A study on abrasive wear characteristics of side plate of FRP ship (온도변화에 따른 유리섬유/폴리우레탄 복합재료의 충격파괴거동)

  • Kim, Byung-Tak;Koh, Sung-Wi
    • Journal of the Korean Society of Fisheries and Ocean Technology
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    • v.45 no.3
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    • pp.188-193
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    • 2009
  • The present study was undertaken to evaluate the effect of temperature on the results of Charpy impact test for glass fiber reinforced polyurethane(GF/PUR) composites. The Charpy impact test were conducted in the temperature range from -50$^{\circ}$ to 50$^{\circ}$. The impact fracture toughness of GF/PUR composites was considerably affected by temperature and it was shown that the maximum value was appeared at room temperature. It is believed that sensitivity of notch on impact fracture energy were increased with decrease in temperature of specimen. As the GF/PUR composites exposed in low temperature, impact fracture toughness of composites decreased gradually owing to the decrease of interface bonding strength caused by difference of thermal expansion coefficient between the glass fiber/polyurethane resin. And decrease of interface bonding strength of composites with decrease in specimen temperature was ascertained by SEM photographs of Charpy impact fracture surface.

Effects of PWHT on Weld Metal Properties of YS 460 MPa Steels for Ship and Offshore Structures (선박·해양 구조물용 YS 460 MPa 강재의 용접금속 특성에 미치는 PWHT의 영향)

  • Kang, Chang-Yong;Jeong, Sang-Hoon
    • Journal of Welding and Joining
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    • v.32 no.4
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    • pp.75-79
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    • 2014
  • This paper has an aim to study the effect of PWHT(for 140min. at $600^{\circ}C$) on FCAW weld metal properties (tensile, charpy impact and CTOD value) of YS 460 MPa steels for ship and offshore structures. On the basis of these study, it was found that strength was decreased and elongation was increased by PWHT. These phenomenon resulted from the reduction of acicula ferrite volume fraction by grain growth. Also, Charpy impact and CTOD value were decreased by PWHT. These phenomenon resulted from grain growth. Because the grain boundary grown by PWHT can play a role as crack initiation site and make the crack propagate more easily. Although weld metal properties were decreased by PWHT, tensile and impact properties could meet the class societies requirements for welds of YS 460 MPa steel, but decrease of fracture toughness need to be consider seriously.

Impact fracture behavior on particle volume fraction of nano silica composite materials (입자 함유율의 변화에 따른 나노 실리카 복합재료의 충격파괴거동)

  • LEE, Jung-Kyu;KOH, Sung Wi
    • Journal of the Korean Society of Fisheries and Ocean Technology
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    • v.51 no.3
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    • pp.454-460
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    • 2015
  • The present study is undertaken to evaluate the effect of volume fraction on the results of Charpy impact test for the rubber matrix filled with nano sized silica particles composites. The Charpy impact tests are conducted in the temperature range $0^{\circ}C$ and $-10^{\circ}C$. The range of volume fraction of silica particles tested are between 11% to 25%. The critical energy release rate $G_{IC}$ of the rubber matrix composites filled with nano sized silica particles is affected by silica volume fraction and it is shown that the value of $G_{IC}$ decreases as volume fraction increases. In regions close to the initial crack tip, fracture processes such as matrix deformation, silica particle debonding and delamination, and/or pull out between particles and matrix which is ascertained by SEM photographs of Charpy impact fracture surfaces.

Mechanical testing of the behavior of steel 1.7147 at different temperatures

  • Brnic, Josip;Turkalj, Goran;Canadija, Marko
    • Steel and Composite Structures
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    • v.17 no.5
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    • pp.549-560
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    • 2014
  • The paper provides the test results and analysis on the behavior of steel 1.7147 at different temperatures. Mechanical uniaxial tests were used to determine mechanical properties, resistance to creep and Charpy impact tests to determine impact energy. Test results are presented in the form of engineering stress-strain diagrams, creep curves as well as numerical data related to impact energy. The results show that the tensile strength has the highest value at room temperature, and the same goes for the yield strength as well as for modulus of elasticity. After room temperature both of mentioned properties decrease with temperature increasing. Some of creep curves were modeled using rheological models and analytical equation. Based on Charpy impact energy an assessment of fracture toughness was made.

강 의 마찰용접 에 미치는 탄소당량 의 영향 - 동종강 에 대하여

  • 나석주;김성도
    • Journal of Welding and Joining
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    • v.3 no.2
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    • pp.1-9
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    • 1985
  • In this study, the influence of carbon equivalents on friction welds of similar steels was investigated. Four types of steels with 15mm diameter tested in the wide range of carbon equivalents from 0.3 to 1.1 Main experimental results are summarized as follows : (1) Under the constant burn-off length, the friction time becomes longer with the increasing carbon equivalent, but the upset length shows no consistent tendencies. (2) Due to the recrystallization in the contact area, the maximum hardness occurs some away from the contact surface. And it increases almost linearly with the increasing carbon equivalent. (3) Even a steel with 1.1 C.E. can be friction welded to make defect-free welds. (4) With the increasing carbon equivalent, the bend angle and charpy impact value decrease very rapidly in the range from 0.3 C. E., but remain nearly unchanged for C. E. higher than 0.6. (5) Heat treatment of the base metals before welding has very little influence on the mechanical properties of welds. On the other hand, normalizing of the welds improves the bend angle and charpy impact value, but its effect becomes almost negligible, when the carbon equivalents are higher than 0.6.

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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.