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CW Nd:YAG 레이저를 이용한 중탄소강과 오스테나이트계 스테인레스강의 이종금속 용접
유영태(Young Tae Yoo),신호준(Ho Jun Shin),안동규(Dong Gu Ahn),임기건(Kie Gon Im),신병헌(Byung Heon Shin) Korean Society for Precision Engineering 2006 한국정밀공학회지 Vol.23 No.3
Laser welding of dissimilar metals has been widely used to improve a wear resistance and a corrosion resistance of the industrial parts. The objective of this research is to investigate the influence of the process parameters, such as the welding for SM45C and STS304 with CW Nd:YAG lasers. The bead-on-plate welding tests arc carried out for several combinations of the experimental conditions. In order to quantitatively examine the characteristics of the dissimilar welding, the welding quality of the cut section, stress-strain behavior and the hardness of the welded metal are investigated. From the results of the investigation, it has been shown that the optimal welding condition without defects in the vicinity of the welded area and with a good welding quality is l600W of the laser power, 0.85m/min of welding speed and 4ℓ/min of pressure for shielding gas.
연속파형 Nd:YAG 레이저를 이용한 SM45C 중탄소강의 레이저표면경화 특성
유영태(Young Tae Yoo),신호준(Ho Jun Shin),안동규(Dong Gu Ahn) Korean Society for Precision Engineering 2005 한국정밀공학회지 Vol.22 No.11
Laser surface hardening technologies have been used to improve characteristics of wear and to enhance the fatigue resistance for automotive parts. The objective of this research work is to investigate the influence of the process parameters, such as. power of laser and defocused spot position, on the characteristics of laser heat treatment for the case of SM45C medium carbon steel. CW Nd:YAG laser is selected as the heat source. The optical lens with the elliptical profile is designed to obtain a wide heat treatment area with a uniform hardness. From the results of the experiments, it has been shown that the maximum hardness is approximatly 780 Hv when the power and the travel speed of laser are 1,095 Wand 0.6 m/min, respectively. In addition, the hardening width using the elliptical lens was three time larger than that using the defocusing of laser beam.
SM45C 중탄소강의 CW Nd:YAG 레이저표면경화와 고주파표면경화특성 비교
신호준(Ho-Jun Shin),유영태(Young-Tae Yoo),안동규(Dong-Gu Ahn),신병헌(Byung-Heon Shin) 대한기계학회 2005 대한기계학회 춘추학술대회 Vol.2005 No.11
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.
Bih Lii Chua(빗리츄아),Ho Jin Lee(이호진),Dong Gyu Ahn(안동규),Jae Gu Kim(김재구) Korean Society for Precision Engineering 2018 한국정밀공학회지 Vol.35 No.2
Wire feeding type directed energy deposition (DED) process is able to produce metal parts with high density at high deposition rate. However, the parts are subjected to high residual stresses and distortion due to its large heat input. In order to simulate the thermal stress, a proper heat input parameter is required. The goal of this paper is to investigate the efficiency and penetration depth of the applied heat flux in the DED process. The estimation method for the penetration depth and efficiency of applied heat flux is proposed using the thermal finite element analyses (FEAs). A finite element model is developed according to the cross sectional profile of the actual deposited beads. A top-hat volumetric heat flux is adopted to simulate the transient thermal phenomenon of the laser based wire feeding type DED process. The estimated heat affected zone (HAZ) from the FEAs is compared with the experimental results in order to estimate the proper efficiency and penetration depth of the laser beam for each condition of DED process.
Bih Lii Chua(빗리츄아),Ho Jin Lee(이호진),Dong-Gyu Ahn(안동규),Jae Gu Kim(김재구) Korean Society for Precision Engineering 2018 한국정밀공학회지 Vol.35 No.9
It is compelling to realize that the additive manufactured part using wire feeding type directed energy deposition (DED) process is subjected to undesired thermal effects, and induced residual stress during the manufacturing process. In order to improve the quality of the manufactured part, the distributions of temperature and residual stress have to be understood to manage the results of the processing of these materials. The objective of this paper is to investigate the influence of the angle of corner deposition on the distributions of temperature and residual stress of the Ti-6Al-4V deposited bead, and the substrate via thermo-mechanical finite element analyses (FEAs). In the same fashion, the formation of the heat affected zone (HAZ) and the stress influenced region (SIR) are estimated from the measured results of the FEAs. Equally important, it can be stated that from the estimated HAZ and SIR regions, the overlapping of undesired thermal effects and residual stress between two beads fabricated by the wire feeding type DED process can be avoided at the design stage.