• Title/Summary/Keyword: surface hardening

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A Study on the Surface Hardening of SCM4 Steel Using a Continuous Wave Nd:YAG Laser (연속파형 Nd:YAG 레이저를 이용한 SCM4강의 표면경화에 관한 연구)

  • Na, Gi-Dae;Shin, Byung-Heon;Shin, Ho-Jun;Yoo, Young-Tae
    • Transactions of the Korean Society of Machine Tool Engineers
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    • v.16 no.5
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    • pp.24-32
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    • 2007
  • Laser surface hardening is beneficially used for surface treatment of structural steel. Due to very rapid heating and cooling rates, structural low-alloy steel(SCM4) can be hardened as self quenching. The aim of this research project is to improve the influence of the process laser parameters: laser power, spot size, surface roughness, and traverse speed. The laser beam is allowed to scan on the surface of the workpiece at the constant power(1095W), varying the traverse speed at 0.3m/min, 0.5m/min and 0.8m/min. The optical lens with the elliptical profile is designed to obtain a wide surface hardening area with uniform hardness. From the results of the experiment, it has been shown that the stable hardness is about 600$\sim$700Hv, when the laser power, focal position and the traverse speed are P=1095W, z=0mm and v=0.3m/min.

Nondestructive Measurement of Case Hardening Depth with Eddy Current Method (와전류법을 이용한 강의 표면경화층 깊이의 비파괴적 측정)

  • Lee, K.W.;Han, S.Y.;Park, U.S.
    • Journal of the Korean Society for Nondestructive Testing
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    • v.11 no.1
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    • pp.38-43
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    • 1991
  • The relationship between eddy current response and case hardening depth has been studied on SM40C(KS D-3752) and SCM440(KS D-3711) steels which were surface hardened by high frequency induction hardening. The results obtained in this study were as follows ; 1) Case hardening depth was successfully measured by observing the eddy current impedance changes of each steel. The impedance decreased linearly with increasing case hardening depth. 2) For large impedance gradient between the hardened surface and core metal, the eddy current response was more sensitive to case hardening depth than for low impedance gradient.

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Design of Robot Direct-Teaching Tool and its Application to Path Generation for Die Induction Hardening

  • Ahn, Jae-Hyung;Sungchul Kang;Changhyun Cho;Jisun Hwang;Mansuk Suh
    • 제어로봇시스템학회:학술대회논문집
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    • 2002.10a
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    • pp.118.5-118
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    • 2002
  • To apply induction hardening method to a press die having 3-D free surface, the induction hardening tool moves on a press die above 1~2mm gap with constant velocity. Since the induction hardening process requires its own hardening path for each die, a direct teaching method which generates working path directly guided by operators is more suitable than an offline method using CAD/CAM data. The direct teaching apparatus in this work includes a teaching tool with a force/torque sensor and data processing computer to finally generate robot's Induction hardening program , in direct teaching operation, an operator teaches working path maintaining contact with surface of press die by holding...

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Surface Hardening of Pine Wood by Laminating of Melamine Resin Sheet (멜라민수지 함침지 적층에 의한 소나무재의 표면 강화)

  • Han, Gyu-Seong
    • Journal of the Korea Furniture Society
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    • v.17 no.1
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    • pp.83-89
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    • 2006
  • Because the surface of pine wood is very soft, there have been many attempts, like as surface coating, resin impregnation, and densificationt, to harden the surface of wood for its interior use. This study was carried out for surface hardening of pine wood by laminating of melamine resin sheet. The effect of laminating method on the characteristics of melamine resin sheet-laminated wood(MLW) was investigated. Flat-sawn softwoods were suitable for MLW making. And the pre-drying of wood at $105^{\circ}C$ for 30min, before laminating, was effective for preparing of defect-free MLW. The abrasion resistance of pine wood was greatly improved by laminating of melamine resin sheet on its surface. Consequently, the laminating of melamine resin sheet was proved to be a favorable method for improvement of surface abrasiveness of pine wood.

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A Study on the Mechanical Properties by High-Frequency Induction Hardening of SCM440 Steel (고주파 담금질에 의한 SCM440강의 기계적 특성에 관한 연구)

  • Ahn, Seok-Hwan;Nam, Ki-Woo;Kim, Tae-Il;Lee, Mun-Yong;Kim, Dong-Kyu
    • Journal of Ocean Engineering and Technology
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    • v.23 no.2
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    • pp.74-80
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    • 2009
  • Surface hardening treatments, such as using the high-frequency induction hardening method, are widely used to increase the fatigue life and prevent the failure of materials by locally increasing the surface hardness. This method, in particular, brings an improvement in static strength by compressive residual surface stress due to the hardening. In this study, the mechanical properties of high-frequency induction hardened SCM440 steel were investigated. These results were also compared with those for base metal and a Q/T (tempering after quenching) treatment specimen. The test results showed that partially high-frequency induction hardened SCM440 steel specimens were more improved in static strength, surface hardness, fatigue limit, and anti-wear than the base metal and Q/T treatment specimens. In particular, the fatigue limit of the high-frequency induction hardened SCM440 steel increased by more than about 52% compared to that of base metal and by about 25% compared to that of the Q/T specimen.

An elastoplastic bounding surface model for the cyclic undrained behaviour of saturated soft clays

  • Cheng, Xinglei;Wang, Jianhua
    • Geomechanics and Engineering
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    • v.11 no.3
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    • pp.325-343
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    • 2016
  • A total stress-based bounding surface model is developed to predict the undrained behaviour of saturated soft clays under cyclic loads based on the anisotropic hardening modulus field and bounding-surface theories. A new hardening rule is developed based on a new interpolation function of the hardening modulus that has simple mathematic expression and fewer model parameters. The evolution of hardening modulus field is described in the deviatoric stress space. It is assumed that the stress reverse points are the mapping centre points and the mapping centre moves with the variation of loading and unloading paths to describe the cyclic stress-strain hysteresis curve. In addition, by introducing a model parameter that reflects the accumulation rate and level of shear strain to the interpolation function, the cyclic shakedown and failure behaviour of soil elements with different combinations of initial and cyclic stresses can be captured. The methods to determine the model parameters using cyclic triaxial compression tests are also studied. Finally, the cyclic triaxial extension and torsional shear tests are performed. By comparing the predictions with the test results, the model can be used to describe undrained cyclic stress-strain responses of elements with different stress states for the tested clays.

Comparison of Characteristics on Induction and Continuous Nd:YAG Laser Surface hardening of SM45C Steel (SM45C강의 연속파 Nd:YAG레이저표면경화와 고주파표면경화특성 비교)

  • Shin H.J.;Yoo Y.T.;Ahn D.G.;Shin B.H.
    • Proceedings of the Korean Society of Precision Engineering Conference
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    • 2005.10a
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    • pp.176-183
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    • 2005
  • Laser heat treatment technology is used for improving the feature of fatigue resistance and wear resistance in mobile parts. The purpose of this study is to compare the characteristics of laser heat treatment and high frequency heat treatment, which is commonly used in industrial place. For the preemptive experiment, the distribution, depth and size of hardening and its micro-structural features were compared between surface heat treatment case by defocusing and variables of each process for heat treatment by exclusively manufactured heat treatment optical system. As a result, high frequency heat treatment has wide distribution of hardening depth and width about 3 times larger than laser heat treatment, however, its average hardness showed 621.4Hv which is smaller than the average hardness of laser heat treatment with 691Hv.

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Development of Soil Surface Hardening Mulching System by Using Paper Mill Sludge Ash (제지슬러지 소각재를 활용한 토양 표면 경화형 멀칭소재 개발)

  • Kim, Dong Sung;Sung, Yong Joo;Cho, Heung-Yeol
    • Journal of Korea Technical Association of The Pulp and Paper Industry
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    • v.46 no.4
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    • pp.85-92
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    • 2014
  • The disposal of the paper mill sludge and the paper mill sludge ash become more important issue, because the environment regulation becomes more strict. In this study, the new mulching system was developed by using the paper sludge ash. The soil surface hardening mechanism for mulching with paper sludge ash, red clay and coal ash was evaluated. Since the CaO in the paper sludge ash provided the harden structure with water, the surface hardening mulching structure could cover the field surface and prevent the germination of weeds. More than 50 w.t.% of red clay and 10 w.t.% of paper sludge ash were required to create the solid soil surface structure for mulching. The field test with the new soil surface hardening mulching system for three months showed the generation of weeds could successfully be inhibited by the system.

Investigation on surface hardening and corrosion characteristic by water cavitation peening with time for Al 5052-O alloy (5052-O 알루미늄 합금의 워터 캐비테이션 피닝 시간에 따른 표면 경화와 부식 특성에 관한 연구)

  • Kim, Seong-Jong;Hyun, Koang-Yong
    • Corrosion Science and Technology
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    • v.11 no.4
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    • pp.151-156
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    • 2012
  • The cavity formed by the ultrasonic generation in the fluid with the application of water cavitation peening collides into the metal surface. At this time, the surface modification effect such as the work hardening presents by the compressive residual stress formed due to the localized plastic deformation. In this investigation, the water cavitation peening technology in the distilled water with the lapse of time was applied to 5052-O aluminum alloy for aluminum ship of a high value. So, the optimum water cavitation peening time on the effect for surface hardening and anti-corrosion property was investigated. Consequently, the water cavitatin peening time on excellent hardness and corrosion resistance characteristic presented 3.5 min. and 5.0 min, respectively. The surface hardness in the optimum water cavitation peening time was improved approximately 45% compared to the non-WCPed condition. In addition, corrosion current density was decreased.