• Title/Summary/Keyword: Laser Surface Hardening

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Surface Treatment in Edge Position of Spheroidal Cast Iron for Mold Materials by Using High Power Diode Laser (High Power Diode Laser을 이용한 금형재료용 구상화 주철의 모서리부 표면처리)

  • Hwang, Hyun-Tae;Song, Hyeon-Soo;Kim, Jung-Do;Song, Moo-Keun;Kim, Young-Kuk
    • Korean Journal of Materials Research
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    • v.19 no.9
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    • pp.457-461
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    • 2009
  • Recently, metal molding has become essential not only for automobile parts, but also mass production, and has greatly influenced production costs as well as the quality of products. Its surface has been treated by carburizing, nitriding and induction hardening, but these existing treatments cause considerable deformation and increase the expense of postprocessing after treatment; furthermore, these treatments cannot be easily applied to parts that requiring the hardening of only a certain section. This is because the treatment cannot heat the material homogeneously, nor can it heat all of it. Laser surface treatment was developed to overcome these disadvantages, and, when the laser beam is irradiated on the surface and laser speed is appropriate, the laser focal position is rapidly heated and the thermal energy of surface penetrates the material after irradiation, finally imbuing it with a new mechanical characteristic by the process of self-quenching. This research estimates the material characteristic after efficient and functional surface treatment using HPDL, which is more efficient than the existing CW Nd:YAG laser heat source. To estimate this, microstructural changes and hardness characteristics of three parts (the surface treatment part, heat affect zone, and parental material) are observed with the change of laser beam speed and surface temperature. Moreover, the depth of the hardened area is observed with the change of the laser beam speed and temperature.

Characteristics on Surface Hardening by using of Continuous Wave Nd:YAG Laser of Cold-Work Die Steel(STD11) about Variation of Focal Lens F-number (초점렌즈 F-수 변화에 의한 냉간금형강 STD11 의 연속파 Nd:YAG 레이저 표면경화 특성)

  • Hwang, Chan-Youn;Yang, Yun-Seok;Lee, Ka-Ram;Yoo, Young-Tae
    • Journal of the Korean Society for Precision Engineering
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    • v.29 no.4
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    • pp.395-408
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    • 2012
  • An experimental investigation with 2.8kW Nd:YAG laser system was carried out to study the effects of different laser process parameters on the microstructure and hardness of STD11. The optical lens with the elliptical profile are designed to obtain a wide surface hardening area with uniform hardness. The Laser beam is allowed to scan on the surface of the work piece varying the power (1600, 1800 and 1900kW) and traverse speed (200, 400, 600, 800 and 1000mm/min) at three different F-numbers of lens. After laser surface treatment three zones, In the microstructure have been observed : melted zone(decarburization), heat affected zone(martensite), and the substrate.

Heat treatment characteristics of medium carbon steel by CW Nd:YAG Laser (CW Nd:YAG 레이저를 이용한 중탄소강의 열처리특성)

  • Shin H.J.;Yoo Y.T.;Ahn D.G.;Im K.
    • Proceedings of the Korean Society of Precision Engineering Conference
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    • 2005.06a
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    • pp.438-443
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    • 2005
  • Laser surface hardening is an effective technique used to improve the tribological properties and also to increase the service life of automobile components such as camshafts, crankshatfs, lorry brake drums and gears. High power CO2 lasers and Nd:YAG lasers are employed for localized hardening of materials and hence are of potential application in the automobile industries. The heat is conducted rapidly into the bulk of the specimen causing self-quenching to occur and the formation of martensitic structure. In this investigation, the microstructure features occurring in Nd:YAG laser hardening SM45C steel are discussed with the use of optical microscopic and scanning electron microscopic analysis. Moreover, This paper describes the optimism of the processing parameters for maximum hardened depth of SM45C steel specimens of 3mm thickness by using CW Nd:YAG laser. Travel speed was varied from 0.6m/min to 1.0m/min. The maximum hardness and case depth fo SM45C steel are 780Hv and 0.4mm by laser hardening.

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A study on the hard surfacing Characteristics of STS420J2 by using Diode laser (Diode laser를 이용한 STS420J2의 표면경화 특성에 관한 연구)

  • Lee, Tae-Yang;Lim, Byung-Chul;Park, Sang-Heup
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.15 no.9
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    • pp.5460-5466
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    • 2014
  • In this study, mainly for kitchen knives and small swords, cutlery, etc. STS420J2 used material used for the experiments. In order to cure the surface of the test piece after the rough grinding and fine grinding was performed in order polishing. Perform the surface hardening of STS420J2 local area by using a diode laser. The output of the laser diode and the feed rate to the process variable. Micro-hardness testing, microstructure testing, scanning electron microscope testing(SEM), the heat input to the analysis. After analyzing the experiment to compare the mechanical properties of the material. When using a diode laser to assess the soundness of the surface hardening. Accordingly, the process for deriving the optimum demonstrate the feasibility.

Microstructure and Hardness Distributions of $CO_2$ Lser Hrdened 12%-Cr Seel (12%-Cr 강의 $CO_2$ 레이저 표면경화에서 금속조직과 경도분포)

  • 김재도
    • Transactions of the Korean Society of Mechanical Engineers
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    • v.16 no.10
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    • pp.1861-1868
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    • 1992
  • Laser beam hardening of 12%-Cr steel has been evaluated by using a continuous wave 3kW co$_{2}$ laser with a hardening mirror set. Experiment was performed on the hardening condition with a laser power of 2.85kW and travel speed of 1.0 and 1.5m/min. Multi passes have been also tried to find the hardening characteristics of partly overlapped zone. The black paint to use at high temperature was adopted to increase the absorptivity of laser beam energy with the wavelength of 10.6.mu.m at the surface of base metal. The microstructure of the hardened layers was observed by using a light microscopy, SEM and TEM. A fine Lamellar martensite formed in the hardened zones exhibits very high Vickers microhardness of 600Hv, whereas the tempered martensite distributes in the base metal with Vickers microhardness of 240Hv.It has been found that laser hardening with multi passes showed no significant drop of the hardness between adjacent passes.

Characteristics of Heat Treatment on Different Materials during Laser Surface Hardening of Cast Iron for Die (금형재료용 주철의 레이저 표면경화처리시 재료에 따른 열처리 특성)

  • Kim, Jong-Do;Song, Moo-Keun;Hwang, Hyun-Tae
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.35 no.12
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    • pp.1663-1668
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    • 2011
  • Surface hardening treatment is required to improve the wear-resistance of press die because severe abrasion of die occurs during the drawing process in which the forming of the automotive body is completed and during the trimming process in which the unnecessary parts are cut. In this study, experiments on the laser surface treatment of press die are performed. Specimens are heat-treated separately at certain plate and edge position by using a diode laser to carry out suitable surface hardening treatment to reduce the wear during the drawing and the trimming processes, and the proper conditions for heat treatment are found. Spheroidal and flake graphite cast iron specimens are used, and the heat treatment characteristics of the two materials are compared. From the results of the study, it is confirmed that the heat treatment characteristics differed depending on the materials.

A study on the hard surfacing Characteristics of SM45C by using Diode laser (다이오드 레이저를 이용한 SM45C의 표면경화 특성에 관한 연구)

  • Lim, Byung-Chul;Lee, Hong-Sub;Park, Sang-Heup
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.16 no.3
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    • pp.1620-1625
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    • 2015
  • In this study, a variety of industrial gears, shafts, chains, rollers, mold, etc. are widely used inautomotive steel carbon steel for machine structural SM45C typical material used for the experiments. In order to cure the surface of the test piece after the rough grinding and fine grinding was performed in order polishing. Perform the surface hardening of SM45C lacal area by using a diode laser. The output of the laser diode and the feed rate to the process variable. Micro-hardness testing, microstructure testing, scanning electron microscope testing(SEM), the heat input to the analysis. After analyzing the experiment to compare the mechanical properties of the material. When using a diode laser to assess the soundness of the surface hardening. Accordingly, the process for deriving the optimum demonstrate the feasibility.

A Numerical Analysis of Eddy-Current Electromagnetic Field for the In-Process Measurement of Case Depth in Laser Surface Hardening Processes (레이저 표면경화공정에서 경화층깊이의 실시간 측정을 위한 와전류 전자기장의 이론적 해석)

  • 박영준;조형석;한유희
    • Transactions of the Korean Society of Mechanical Engineers
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    • v.18 no.3
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    • pp.529-539
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    • 1994
  • In laser heat treatment process of steels, the thin layer of substrate is rapidly heated to the austenitizing temperature and subsequently cooled at a very fast rate due to the self-quenching effect. Consequently, it is transformed to martensitic structure which has low magnetic permeability. This observation facilitates the use of a sensor measuring the change of electromagnetic field induced by the hardening layer. In this paper, the eddy-current electromagnetic field is analyzed by a finite element method. The purpose of this analysis is to investigate how the electrical impedance of the sensor's sensing coil varies with the change in permeability. To achieve this, a numerical model is formulated, taking into consideration the hardening depth, distance of the sensor from the hardened surface and the frequency driving the sensor. The results obtained by numerical simulation show that the eddy-current measurement method can feasibly be used to measure the changing hardening depth within the frequency range from 10 kHz to 50 kHz.