• 한국기계가공학회지
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• 제10권1호
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• pp.31-37
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• 2011

Recently, the technology of surface treatment is being more important which affects the material cost reduction and substitution to the expensive material. The material used for the mechanical processing should have not only high intensity, but also strength toughness, wear resistance and corrosion resistance. In order to increase the durability and have better quality of the parts using such kind of tooling material, various kinds of research of the surface hardening through many kinds of heat resources is being done and practically applied. In this study, the characteristics of hardening surface zone for high strength of the press die material through laser beam irradiation are researched. In this study, it is experimentally observed by the status of the surface morphology, tensile strength, the hardness distribution of the base metal and wear condition by the surface hardness pattern by the laser beam based on the process parameters of $CO_2$ laser by using SM45C and STD11 used for press tool. Through this research, the characteristics of surface hardened zone for high strength of the thin metal by laser beam irradiation is done.

• 열처리공학회지
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• 제23권5호
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• pp.257-262
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• 2010

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.

• 한국기계가공학회지
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• 제9권4호
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• pp.44-52
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• 2010

Recently, with the high performance and efficiency of machine, there have been required the multi-functions in various machine parts, such as the heat resistance, the abrasion resistance and the stress resistance as well as the strength. Fatigue crack growth tests were carried out to investigate the fatigue characteristics of high carbon steel (SM53C) experienced by high-frequency induction treatment. The influence of high-frequency induction treatment on fatigue limit was experimentally examined with the specialfocus on the variation of surface microstructure and the fatigue crack initiation and propagation through fractography. Also, the shape of hardening depth, hardened structure, hardness, and fatigue-fracture characteristics of SM53C composed by carbon steel are also investigated.

• 한국정밀공학회지
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• 제10권2호
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• pp.66-75
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• 1993

This paper proposes a monitoring method for nondestructive and in-process measurement of the case depth in LASER surface heat treatment process. The method is essentially an eddy-current method, and measures sensing coil's electrical impedance which varies with the changes of the material microstructure due to hardening. To investigate te validity of the proposed method a series of experiments were performed for various hardning depths. The results show that the relationship between the eddy- current sensor output and the changes in case depth is almost linear. This indicates that the eddy-current measuring method can be used as one of the possible monitoring method for mesauring the hardened depth in LASER heat treatment processes.

• 열처리공학회지
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• 제2권3호
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• pp.1-4
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• 1989

• 열처리공학회지
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• 제2권1호
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• pp.21-26
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• 1989

• Journal of Advanced Marine Engineering and Technology
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• 제35권8호
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• pp.1041-1047
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• 2011

본 연구에서는 거의 모든 기반산업에서 필수적인 생산기술로 사용되고 있는 금형의 기계적 성질을 향상시키기 위해 고출력 다이오드 레이저를 이용하여 두 종류의 금형재료용 주철을 표면경화처리하였다. 우선, 구상흑연 주철인 FCD550 소재에 대하여 열처리 특성을 파악한 후, 편상흑연 주철인 HCI350 소재를 열처리하여 두 소재의 표면경화 특성을 비교하였다. 경화부의 경도는 두 시험편 모두 모재에 비해 3배 이상의 경도 상승을 보였지만, 재료에 포함된 흑연의 함유량 및 형상의 차이에 의한 재료의 열전도도에 따라서 FCD550 소재에 비해 HCI350이 열처리하는데 있어서 더 많은 입열이 요구되었다.

• Journal of Advanced Marine Engineering and Technology
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• 제36권1호
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• pp.78-84
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• 2012

금형의 공정 과정에서 금형과 성형품 사이에서 발생하는 마찰로 인해 발생하는 금형의 마모가공차로 작용하여 성형 품질을 저하시킬 수 있다. 따라서 금형의 내마모성을 향상시키기 위해 질화나 침탄처리, 화염 및 고주파 표면처리 등의 방법들이 적용되어 왔다. 하지만 형상의 제한이나 제품의 변형 등과 같은 문제점을 수반하고 있기 때문에, 이러한 문제점을 해결할 수 있는 표면처리 방법으로써 레이저 표면처리 기술이 검토되고 있다. 따라서 본 연구에서는 고출력 다이오드 레이저를 이용, 금형재료용 주철의 표면처리를 시도하였다. 앞서 제1보와 제2보의 논문에서는 금형의 재료 및 형상의 차이에 따른 열처리 특성을 비교하였다면, 본 논문에서는 열처리 후 생성되는 경화부, 경계부위 및 모재의 조직적 차이를 분석하기 위해 광학 현미경 및 전자 현미경을 이용하여 미세조직을 관찰하고, EDS를 통해 조직의 상태를 파악하였다. 미세조직 관찰 결과, 경화부는 침상의 마르텐사이트 조직이 형성되어 있었다.

• 연구논문집
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• 통권26호
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• pp.121-132
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• 1996

The carburising surface modification treatment of the die steel has been used for improving wear resistance and heat cycle strength of the die and preventing a pitting on the surface because the carbides are forming in the matrix during carburising. Generally, the hot forging die was used after quenching-tempering treatment or nitriding after quenching-tempering treatment. The nitriding after carburising on the surface of a hot die steel and a wear resistance die steels was suggested by SOUCHARD, JACQUOT. and BUVRON. This surface modification treatment improved the adhesive and abrasive wear resistance and friction coefficient. The process was introduced to the forging die of stainless steel, titanium alloy steel, alloy and medium carbon steel and the physical properties of the die after the treatment were improved. The surface hardening treatment of the nitriding, the carburising, the boriding, and TD process were used to improved the life time of the forging die. Also, the coating process of PVD, CVD and PCVD were used and the hard chromium plating was occasionally used. Therefore, this study analyzed the effects of the carburising time and the conditions of nitriding on STD61 steel. The case depth, the surface hardness, the forming carbide size and shape during overcarburising process on the die steel were also examined.

• 열처리공학회지
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• 제13권3호
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• pp.196-202
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• 2000