• Title/Summary/Keyword: Hardness Absorbed impact energy

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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.

A Study on the Mechanical Properties Change by Stress Aging of 2.25Cr-1Mo Steel (2.25Cr-1Mo 강의 응력 시효에 의한 기계적 특성 변화에 대한 연구)

  • Yang, Hyun-Tae;Kim, Sang-Tae
    • Proceedings of the KSME Conference
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    • 2001.06a
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    • pp.517-522
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    • 2001
  • The purpose of this study is to investigate the thermal embrittlement and the mechanical properties of 2.25Cr-1Mo steel aged at high temperature and stress for 250 hours. Original, aged artificially material were tested to obtain the hardness and impact absorbed energy. Hardness and impact absorbed energy decreased with the increasing aging time. The carbide morphology with the thermal embrittlement was found to contribute to the mechanical property change by X-Ray diffraction method.

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A Study on the Mechanical Strength Change by Thermal Aging of 2.25Cr-1Mo Steel (발전설비용 2.25Cr-1Mo 강의 시효에 의한 기계적 강도 특성 변화에 대한 연구)

  • Yang, Hyeon-Tae;Kim, Sang-Tae
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.24 no.7 s.178
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    • pp.1771-1778
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    • 2000
  • The purpose of this study is to investigate the thermal embrittlement and the mechanical properties of 2.25Cr-1Mo steel aged at high temperature for the extended periods. Original, aged artificiall y and used material were tested to obtain the tensile strength, hardness and impact absorbed energy. Tensile strength, hardness and impact absorbed energy decreased with the increasing aging time. The carbide morphology with the thermal embrittlement was found to contribute to the mechanical property change by X-Ray diffraction method.

Effect of Hydrogen Charging on the Mechanical Properties of 304 Stainless Steels

  • Lee, Sang-Pill;Hwang, Seung-Kuk;Lee, Jin-Kyung;Son, In-Soo;Bae, Dong-Su
    • Journal of Power System Engineering
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    • v.19 no.5
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    • pp.73-79
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    • 2015
  • The effects of hydrogen charging on the mechanical properties of 304 stainless steels were investigated in conjunction with the detailed examinations of their fracture modes. The dependence of the absorbed impact energy and the surface hardness of the 304 stainless steels on the hydrogen charging time was characterized. The tensile properties of the 304 stainless steels by the variation of cross-head speed were also evaluated at the room temperature. The hydrogen charging was performed by an electrolysis method for all specimens of the 304 stainless steels. The mechanical properties of the 304 stainless steels exhibited the sensitivity of embrittlement due to a hydrogen charging. The correlation between mechanical properties and fracture surfaces was discussed.

The effect of Tempering on the Mechanical Properties of Mod. 440A Martensitic Stainless Steel (Mod. 440A 마르텐사이트 스테인리스강의 기계적 성질에 미치는 템퍼링의 영향)

  • Kwon, S.D.;Kim, Y.C.;Kang, C.Y.
    • Journal of the Korean Society for Heat Treatment
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    • v.26 no.3
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    • pp.120-125
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    • 2013
  • In this study, the effect of tempering treatment on the mechanical properties in modified 440A steel has been investigated. The amount of remaining carbide decreased with increasing the austenitizing treatment temperature, and all carbides were completely dissolved at $1250^{\circ}C$. The amount of remaining carbide decreased with increasing the time of austenitizing, but the carbide remained insoluble up to 120 minutes at $1050^{\circ}C$. With increasing the tempering temperature, tensile strength decreased, and elongation increased slowly, while hardness rapidly decreased, and impact value unchanged and then rapidly increased over $500^{\circ}C$. The strength and hardness slowly decreased, while the elongation and impact absorbed energy increased with increasing the tempering time. $Cr_{23}C_6$ type carbide was precipitated and sharp decrease of elongation and toughness by tempering did not appear.

Correlation Study of Microstructure and Mechanical Properties in Heat Affected Zones of API X80 Pipeline Steels containing Complex Oxides (복합산화물이 형성된 API X80 라인파이프강의 용접열영향부 미세조직과 기계적 특성의 상관관계 연구)

  • Shin, Sang Yong;Oh, Kyoungsik;Lee, Sunghak
    • Korean Journal of Metals and Materials
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    • v.47 no.2
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    • pp.59-70
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    • 2009
  • This study is concerned with the correlation between microstructure and mechanical properties in heat affected zones (HAZs) of API X80 pipeline steels containing complex oxides. Three kinds of specimens were fabricated by varying alloying elements of Ti, Al, and Mg to form complex oxides, and their microstructures, Vickers hardness, Charpy impact properties were investigated. The number of complex oxides increased as the excess amount of Ti, Al, and Mg was included in the steels. The simulated HAZs containing a number of oxides showed a high volume fraction of acicular ferrite region because oxides acted as nucleation sites for acicular ferrite. According to the correlation study between thermal input, volume fraction of acicular ferrite region, and Charpy impact properties, the ductile fracture occurred predominantly when the volume fraction of acicular ferrite region was 65% or higher, and the Charpy absorbed energy was excellent over 200 J. When the volume fraction of acicular ferrite region was 35% or lower, the Charpy absorbed energy was poor below 50 J as the brittle cleavage fracture occurred. These findings suggested that the active nucleation of acicular ferrite in the oxide-containing steel HAZs was associated with the great improvement of Charpy impact properties of the HAZs.

Study on the impact fracture behavior with the ferrite-martensite dual phase steels (페라이트-마르텐사이트 複合組織鋼의 衝擊破壞擧動)

  • 송삼홍;오택렬
    • Transactions of the Korean Society of Mechanical Engineers
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    • v.12 no.1
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    • pp.19-27
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    • 1988
  • The mechanical properties of Ferrite-Martensite dual phase steels are affected by microstructural factors, such as, martensite volume fractions, grain size of ferrite, hardness ratio of Ferrite-Martensite, connectivity and chemical components etc. Therefore, this study has been made on the influence of Impact fracture behavior which changes the hardness ratio of Ferrite-Martensite by mean of heat treatment of low carbon Mn-Steels. In order to analyze and examine the effect of fracture behavior under impact load, this study investigated the impact strength, the impact loading time, the absorbed energy on the fracture ductility of Ferrite-Martensite dual phase steels, the formation of micro crack and slip, and plastic restraint of martensite on the plastic deformation.

Effects of Tempering Treatment on Microstructure and Mechanical Properties of Cu-Bearing High-Strength Steels (템퍼링에 따른 Cu 첨가 고강도강의 미세조직과 기계적 특성)

  • Lee, Sang-In;Hwang, Byoungchul
    • Korean Journal of Materials Research
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    • v.24 no.10
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    • pp.550-555
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    • 2014
  • The present study deals with the effects of tempering treatment on the microstructure and mechanical properties of Cu-bearing high-strength steels. Three kinds of steel specimens with different levels of Cu content were fabricated by controlled rolling and accelerated cooling, ; some of these steel specimen were tempered at temperatures ranging from $350^{\circ}C$ to $650^{\circ}C$ for 30 min. Hardness, tensile, and Charpy impact tests were conducted in order to investigate the relationship of microstructure and mechanical properties. The hardness of the Cu-added specimens is much higher than that of Cu-free specimen, presumably due to the enhanced solid solution hardening and precipitation hardening, result from the formation of very-fine Cu precipitates. Tensile test results indicated that the yield strength increased and then slightly decreased, while the tensile strength gradually decreased with increasing tempering temperature. On the other hand, the energy absorbed at room and lower temperatures remarkably increased after tempering at $350^{\circ}C$; and after this, the energy absorbed then did not change much. Suitable tempering treatment remarkably improved both the strength and the impact toughness. In the 1.5 Cu steel specimen tempered at $550^{\circ}C$, the yield strength reached 1.2 GPa and the absorbed energy at $-20^{\circ}C$ showed a level above 200 J, which was the best combination of high strength and good toughness.

Impact Toughness and Fracture Behavior in Non-Heat Treating Steels Containing Bainite (베이나이트 함유 비조질강의 충격인성 및 파괴거동)

  • Cho, Ki-Sub;Kwon, Hoon
    • Journal of the Korean Society for Heat Treatment
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    • v.32 no.4
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    • pp.161-167
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    • 2019
  • Impact toughness and fracture behavior were studied in five kinds of non-heat treating steels containing bainite; standard(0.25C-1.5Mn-0.5Cr-0.2Mo-0.15V), high V(0.3V), Ni(0.5Mn-2Ni), W(0.4W instead of Mo), and high C-Ni(0.35C-0.5Mn-2Ni) steels. The good hardness and impact toughness balance was exhibited in the $1100^{\circ}C$-rolled condition, while the impact toughness was deteriorated due to coarse grained microstructure in the $1200^{\circ}C$-rolled condition. The impact toughness decreased with increasing the hardness in all steels studied. The fracture behavior was also basically identical, that is, the fracture area was divided into 3 zones; shear and fibrous zone, fracture transition zone with ductile dimples and cleavage cracks, where the cracks initiate and grow to critical size, unstable cleavage fracture propagation zone. The energy absorbed for the critical crack formation through the plastic deformation inside the plastic zone in front of the notch root contributed to a mostly significant portion of the total impact energy.

Determination of Shock Absorption Performance and Shear Modulus of Rubbers by Drop Impact Test (낙하충격실험을 통한 고무의 충격흡수성능과 전단계수 평가)

  • Kang, Dong-Hwan;Seo, Mu-Yeol;Gimm, Hak-In;Kim, Tae-Won
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.33 no.4
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    • pp.321-328
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    • 2009
  • Shock absorption performances of various rubbers were investigated by using drop impact test. Several types of rubber such as NR, NBR, EPDM, SR and PUR with three respective levels of shore hardness were used for the test. As in the cases, the absorbed impact energies in rubbers were measured under seven different loads against impact energy between 5-80J. The impact absorption efficiencies of the rubbers then were evaluated by means of both single impact energy condition and summation of all impact energy applied condition. As shown in the results, PUR and EPDM have better shock absorption performances than other rubbers. Further analysis was extended to determine a shear modulus of SR through the finite element implementation with Blatz-Ko model. As can be seen, relatively higher level of absorption energy results in a decreasing shear modulus.