• Title/Summary/Keyword: surface hardening

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A concrete plasticity model with elliptic failure surface and independent hardening/softening

  • Al-Ghamedy, Hamdan N.
    • Structural Engineering and Mechanics
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    • v.2 no.1
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    • pp.35-48
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    • 1994
  • A plasticity-based concrete model is proposed. The failure surface is elliptic in the ${\sigma}-{\tau}$ stress space. Independent hardening as well as softening is assumed in tension, compression, and shear. The nonlinear inelastic action initiates from the origin in the ${\sigma}-{\varepsilon}$(${\tau}-{\gamma}$) diagram. Several parameters are incorporated to control hardening/softening regions. The model is incorporated into a nonlinear finite element program along with other classical models. Several examples are solved and the results are compared with experimental data and other failure criteria. "Reasonable results" and stable solutions are obtained for different types of reinforced concrete oriented structures.

A Study on the Surface Harding of Aluminum Alloy - TIG Overlay Hardening of Al 5083- (알루미늄합금의 표면강화에 관한 연구 - Al 5083에 대한 TIG overlay 경화 -)

  • 이영호;강원석;이규천
    • Journal of Welding and Joining
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    • v.15 no.1
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    • pp.135-148
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    • 1997
  • It was attempted to improve wear resistance and durability under the load surface pressure that make a formation of the thick (mm-order) hard-surfacing layer for aluminum alloy of 5083. The thick hard layers were formed on the surface of 5083 by TIG overlay method. Al-(25.4, 33.6, 45.7 mass%) Cu filler metals which were newly developed were overlaid on two base metals forming the one bead, one layer and two layers. The investigation was made on the characteristics of hardening and wear resistance in relation to the microstructure of overlaid layers with selection of optimum overlaying condition.

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A Study on the Surface Soil Stabilization Method on Marine Clay (해성점성토의 표층안정처리 공법에 관한 연구)

  • 천병식;한기열
    • Proceedings of the Korea Committee for Ocean Resources and Engineering Conference
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    • 2000.10a
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    • pp.129-134
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    • 2000
  • Hardening agent has been the traditional material for surface soil stabilization a sat ground This study aims at determining optimal mixture ratio of hardening agent in accordance with the required design specificutions. Hardening agent is properly mixed with Fly ash, Gyosum, Slag and Cement for the etmmngite hydrates which is dective for early stabilization of unconsoliokrred soil. \ulcornerhe treated soil is the clay tint is widely found here and there in Koresz In this study, preliminary tests were performed to get optirml mixture ratio of stabilizer ingredient, and mrvine clay in Jin-Hae was used to get physid and Md properties. Labomtory tests of 50 stabilized soil were performed to get optimal mixture mtio for 16-stabilizer merial a 6 types, a d stabilizer mixing was determined

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Ion Nitriding Using Pulsed D.C Glow Discharge Combined with Inductively Coupled Plasma (펄스직류방전과 유도결합방전의 복합에 의한 SCM440강의 이온질화)

  • Kim, Yoon-Kee
    • Journal of the Korean institute of surface engineering
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    • v.43 no.2
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    • pp.91-96
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    • 2010
  • SCM440 steels were nitrided using pulsed dc plasma combined with inductively coupled plasma (ICP) generated by 13.56 MHz rf power in order to enhance case hardening depth. The case hardening depth was increased with rf power. The effective case-depth with ICP at 900 watt was as 1.6 times as that nitrided without ICP. The hardening depth was also increased up to 1.45 times. The compound layers formed on top surface were dense and thin when pulsed dc plasma was combined with ICP.

Development Process for High Power Diode Laser for Metal Surface Hardening (금속 표면경화용 고출력 다이오드 레이저 개발 프로세스)

  • Jang, Dong-Hwan
    • Journal of the Korean Society of Manufacturing Process Engineers
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    • v.21 no.2
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    • pp.11-22
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    • 2022
  • This paper presents the development process for a high-power diode laser for metal surface hardening. To combine the emissions from several laser bars, it is necessary to collimate the emitted light using an optical lens. Thus, to achieve a suitable power density and uniform beam profile, several optical layouts were proposed. To estimate the laser beam for a flat-top distribution, a numerical analysis was performed using the ZEMAX software, and the results were compared with the experimental results. With a focal lens assembled in a serial diode stack source, the design can utilize the advantage of compacting the overall beam size. Experimental results for a robotic system demonstrated the processing ability of this diode laser module in industrial laser hardening.

Laser Hardening of Piston Ring Groove (피스톤 링그루브의 레이저 열처리)

  • Song, Y.K.;Suh, S.
    • Journal of the Korean Society for Heat Treatment
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    • v.10 no.3
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    • pp.165-171
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    • 1997
  • Laser hardening for the piston ring groove of ductile cast iron was tried. Mechanical and microstructural investigation for the hardened area indicated that the laser heating technique could replace conventional induction hardening process completely and further showed that post grinding process would be eliminated by minimizing bulging of heat treated area. In laser hardening, the volume increase caused by martensitic phase transformation proved to be less than $10{\mu}m$, which insures no post machining on the hardened surface. As expected, the depth of hardening was inversely proportional to the beam scanning velocity and the highest surface hardness was obtained at the beam velocity of 0.75m/min. Heat treatment using phosphate coating demonstrated quite comparable result to the case of graphite suscepter.

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The Laser hardening Characteristics of the Alloy Tool Steels STD11 (금형용 합금공구강 STD11의 레이저 표면경화 특성)

  • Cho, Y.M.;Kim, J.D.
    • Journal of the Korean Society for Heat Treatment
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    • v.6 no.4
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    • pp.230-236
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    • 1993
  • The laser beam hardening has been experimentally tried to find the hardened characteristics of STD11. Experiment was performed on the optimum hardening condition with 2kW $CO_2$ laser. The microstructure of the hardened layers was observed using the microscope. The hardened zones exhibits very high Vickers microhardness of 720 Hv, however, the deoxidation was observed under the surface of hardened area. The case depth of hardened zones is about 0.6mrn and case width is 4mm. FEM-simulation on laser surface hardening of STD11 steel are described. With the proper assumption of the absorbed energy density, the calculated case depth and width in 2 kW $CO_2$ laser hardening were in good agreement with the experimental result. It was found that there is optimum absorbed energy density of STD11.

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Yield Surface and Hardening Laws of Unsaturated Clayey Soils for Isotropic Compression (불포화 점성토의 등방압축 상태에서 발생하는 항복곡면과 경화감수)

  • 송창섭
    • Magazine of the Korean Society of Agricultural Engineers
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    • v.39 no.1
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    • pp.93-101
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    • 1997
  • This paper presents yield surfaces and hardening laws for describing the state of an unsaturated soil under isotropic compression and suction changes. The yield surface is formulated within the framework of hardening plasticity using two independent sets of stress variables : the excess of total stress over air pressure and the suction. And the application of the yield surfaces and hardening laws are confirmed from the result of the experiment. To this end a series of suction-controlled isotropic tests are conducted on clayey soils. Matric suction is controlled by the axis translation technique using high air entry ceramic disk. The specimens are compacted using a half of Proctor compaction energy with 5 % lower of water content than the optimum moisture contents. From test results, existence of the yield surfaces and an application of hardening laws to samples are confirmed by comparison between test and predicted results. And it is confirmed that LC yield locus is extened with the total plastic deformations induced by suction or stress changes, however, SI yield locus is only extended with the plastic deformations by induced suction changes.

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Effect of Micro-hardening Additive on the Mechanical Property of Electroplated Copper Foil (Micro-hardening 원소 첨가가 전해동박의 기계적 특성에 미치는 영향)

  • Park, Seong-Cheol;Son, Seong-Ho;Kim, Jin-Hwa;Kim, Hyeong-Mi;Lee, Ho-Nyeon;Lee, Hong-Gi
    • Proceedings of the Korean Institute of Surface Engineering Conference
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    • 2014.11a
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    • pp.122-122
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    • 2014
  • 본 연구에서는 micro-hardening을 통한 고강도 고연성 전해동박을 제조하기 위해 Sn, Co, Zn 등의 원소 첨가량, 전류밀도, 전해액 온도, 첨가제 제어 등의 공정조건 변화에 따른 전해동박층의 표면 형상, 조성 및 전기전도도를 평가하였고, 인장강도와 연신율을 평가하였다.

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Finite element analysis for surface hardening of SM45C round bar by diode laser (다이오드 레이저를 이용한 SM45C 환봉 표면경화 열처리의 유한요소해석)

  • Cho, Hae-Yong;Kim, Kwan-Woo;Lee, Jae-Hoon;Suh, Jeong;Kim, Jong-Do
    • Proceedings of the KSME Conference
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    • 2007.05a
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    • pp.683-688
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    • 2007
  • Surface heat treatment of SM45C round bar by diode laser was simulated to find it's condition by using commercial finite element code MARC. Due to axisymmetric geometry, a quarter of model for SM45C round bar was considered and user subroutines were applied to boundary condition for the heat transfer. Material properties such as conductivity, specific heat and mass density were given as a function of temperature. Rotation speed of round bar and feed rate of beam were considered to design heat source model. Shape parameter values of heat source were determined by beam profile. As results, Three dimensional heat source model for diode laser beam conditions of surface hardening has been designed by the comparison between the finite element analysis results and experimental data on SM45C round bar. Diode laser surface hardening for SM45C round bar was successfully simulated and it should be useful to determine optimal heat treatment condition.

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