• 제목/요약/키워드: penetration welding

검색결과 355건 처리시간 0.028초

TWB용 고강도 박판 강재의 $CO_2$ 레이저 용접성 및 성형성 ([ $CO_2$ ] Laser Weldability and Formability of High Strength Steels for Tailored Blanks Applications)

  • 이원범;박성호
    • 한국소성가공학회:학술대회논문집
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    • 한국소성가공학회 2004년도 춘계학술대회 논문집
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    • pp.365-372
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    • 2004
  • 1)고강도강 BOP 시험 결과 강종에 차이 없이 용접속도에 따라 유사한 비드 형상을 가지는 것으로 나타났다. 한편 1.2t 시험편의 적정 용접속도는 $4\~8m/min$으로 나타났다. 2) 용접속도가 빠를수록 비드폭은 작아지며, 경도값은 높게 나타났다. 그리고, 최고 경도값은 강의 성분(Ceq)에 비례하는 것으로 나타났음, 그 결과 TRIP80(Ceq=0.53)의 경우 최고 520Hv이상의 경도값을 가지고 있었다. 3) LDH test 결과 DP강의 모재대비 용접부의 성형성이 약 $90\%$ 정도로 나타났으며, TRIP 및 일반 고강도강은 약 $80\%$의 성형성을 갖는 것으로 확인되었다. 4) He을 보호가스로 사용시 기공의 형성은 크게 억제되었다. 그리고 Ar 사용시에는 기공 형성이 He에 비해 많이 형성되는 것으로 나타나 사용시 주의가 필요한 것으로 보인다. 기공 형성은 TRIP > 60C/45R > DP 순서로 나타나 DP강이 가장 좋은 레이저 용접성을 가지고 있었다.

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국부건식(물커튼식)수중용접법에 관한 연구 (A Study on Locally Drying Underwater Welding)

  • 이규복;황선효;박영조;김종열
    • Journal of Welding and Joining
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    • 제10권2호
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    • pp.51-62
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    • 1992
  • A torch was designed and fabricated in order to develope the technology of "locally drying underwater welding" by water curtain method. The condition for the formation of the possible local cavity, the mechanical properties and the thermal cycle of welds were investigated in the developed welding equipment compared with in-air welding. The possibility of highly reliable and practical underwater welding was found. The proper local cavity was formed above the water flowrate of 30l/min and CO$_{2}$ gas flowrate of 100l/min. The bead width and penetration depth were increased with increasing welding current. The hardness of weldments is about 160Hv in air welding, but about 210Hv in underwater welding. The elongation and the impact value of underwater weldments are 15% and 6Kg/cm$^{2}$ respectively, which are only half as much as the values of in-air welding. The cooling time in the temperature range from 800.deg.C to 500.deg.C affecting the structure and the hardness of weldments is about 22sec. in air welding while about 10sec. in underwater welding.r welding.

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Neuro-Fuzzy를 이용한 GMA 용접의 비드형상 추론 알고리즘 개발 (Development of Inference Algorithm for Bead Geometry in GMAW using Neuro-Fuzzy)

  • 김면희;이종혁;이태영;이상룡
    • 한국정밀공학회:학술대회논문집
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    • 한국정밀공학회 2002년도 춘계학술대회 논문집
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    • pp.608-611
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    • 2002
  • In GMAW(Gas Metal Arc Welding) process, bead geometry (penetration, bead width and height) is a criterion to estimate welding quality. Bead geometry is affected by welding current, arc voltage and travel speed, shielding gas, CTWB (contact- tip to workpiece distance) and so on. In this paper, welding process variables were selected as welding current, arc voltage and travel speed. And bead geometry was reasoned from the chosen welding process variables using negro-fuzzy algorithm. Neural networks was applied to design FL(fuzzy logic). The parameters of input membership functions and those of consequence functions in FL were tuned through the method of learning by backpropagation algorithm. Bead geometry could be reasoned from welding current, arc voltage, travel speed on FL using the results learned by neural networks.

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웨이브렛 변환을 이용한 전자빔 용접 진단 (Electron Beam Welding Diagnosis Using Wavelet Transform)

  • 윤충섭
    • Journal of Welding and Joining
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    • 제21권6호
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    • pp.33-39
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    • 2003
  • Wavelet transform analysis results show a spectrum energy distribution of CWT along scale factors distinguish the partial, full and over penetration in a electron beam welding by analyzing the curve of spectrum energy at small scale, middle and large scale range, respectively. Two types of signals collected by Ion collector and x-ray sensors and analyzed. The acquired signals from sensors are very complicated since these signals are very closely related the dynamics of keyhole which interact the very high density energy with materials during welding. The results show the wavelet transform is more effective to diagnosis than Fourier Transform, further for the general welding defects which are not a periodic based, but a transient, non-stationary and time-varying phenomena.

용접변형의 고정도 예측을 위한 지배인자의 정당성 검증 (Verification of Validity of Governing Factors in High Accurate Prediction of Welding Distortion)

  • 이재익;장경호;김유철
    • Journal of Welding and Joining
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    • 제31권5호
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    • pp.7-14
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    • 2013
  • The legitimacy of dominating factor in the high accuracy prediction of welding distortion was investigated for butt welding and fillet welding. When out-of-plane distortion was measured by the experiment objecting to butt welding, if tack welding was easily performed, the position of a neutral axis was variously changed by the irregularity. Then, there have been a case that out-of-plane distortion was generated in the unexpected direction. This case should be especially noted. New model for the experiment was proposed so as to solve this problem. As it was elucidated by the case of fillet welding, it was verified that the analysis should be carried out with satisfying the yield condition (especially at high temperature above 700 degree Celsius) and with closely simulating the penetration shape (heat input in weld metal) in order to solve the proposition that is the high accuracy prediction of welding distortion. It was confirmed that residual stress is highly predicted because welding distortion is highly predicted, too.

API X-100의 레이저-아크 하이브리드 용접성에 미치는 용접와이어의 영향 (The Effects of Welding Wires on the Weldabilities of API X-100 with Laser-Arc Hybrid Welidng)

  • 김성욱;이목영
    • Journal of Welding and Joining
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    • 제32권5호
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    • pp.7-12
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    • 2014
  • In this study, API-X100 steel pipes were welded with various kinds of welding wires in the laser-arc hybrid welding process. 10kW fiber laser source was combined to MIG arc welding process. API X-100 steel of base metal was of 16.9mm thickness, and butt welding applied. After welding, full penetration weld was acquired by 1-pass welding. A root porosity and the lack of fusion was observed in some welding conditions. By the mixing the melted wire, acicular ferrite, polygonal ferrite, pro-eutectoid, aligned side plate, and bainite structures were observed at the weld metal. From the observation of hybrid weld, unmixed zone had more Ni and Cr. The unmixed zone was a 1/3 area of the weld metal. As the mechanical test of the hybrid welding, tensile test and impact test applied. From the tensile test, all of the welding except SM70S was fractured at the base metal. The result of the impact test at -30 degree C led 60J~320J of the absorbed energy. The result of the low-absorbed energy might be from the coarse equiaxed structures of the weld metal.

신경회로망과 수학적 방정식을 이용한 최적의 용입깊이 예측에 관한 연구 (A Study on Prediction of Optimized Penetration Using the Neural Network and Empirical models)

  • 전광석
    • 한국생산제조학회지
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    • 제8권5호
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    • pp.70-75
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    • 1999
  • Adaptive control in the robotic GMA(Gas Metal Arc) welding is employed to monitor the information about weld characteristics and process paramters as well as modification of those parameters to hold weld quality within the acceptable limits. Typical characteristics are the bead geometry composition micrrostructure appearance and process parameters which govern the quality of the final weld. The main objectives of this paper are to realize the mapping characteristicso f penetration through the learning. After learning the neural network can predict the pene-traition desired from the learning mapping characteristic. The design parameters of the neural network estimator(the number of hidden layers and the number of nodes in a layer) were chosen from an error analysis. partial-penetration single-pass bead-on-plate welds were fabricated in 12mm mild steel plates in order to verify the performance of the neural network estimator. The experimental results show that the proposed neural network estimator can predict the penetration with reasonable accuracy and gurarantee the uniform weld quality.

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슬리브덮개를 이용한 배관 보수용접시 필릿용접부의 기계적특성에 관한 연구 (A Study on Mechanical Properties of Fillet Weldment in Pipeline Repair Welding Using Sleeve)

  • 김영표;김형식;김우식;홍성호
    • Journal of Welding and Joining
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    • 제14권5호
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    • pp.49-58
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    • 1996
  • In Korea Gas Corporation, as one of the pipeline repairing methods, damaged pipelines are sometimes treated with a temporally employment of split sleeve. On conducting the repair process, circumferential fillet and longitudinal groove welding usually must be included. For the case of groove welding, a considerable amount of R&D have been carried out related to property changes, while few study on the property change in fillet welding has been conducted. In this paper, so as to confirm the specification of fillet welding in terms of safety and reliability, properties changed by fillet welding were investigated for two welding processes. Qualifying tests such as reviewing macrostructure and nick-break tests were performed according to API 1104 and ASME section IX. In addition, tensile properties and hardness were evaluated according to KS B0841 and BS 4515. The fillet weld prepared by the qualified procedure showed melting depth of 0.8∼1.3mm and heat affected zone of 2.8∼3.4mm length. No crack and lack of penetration were observed. And the results of hardness and nick-break tests satisfied code requirements. The area crossed by fillet and groove welding line was found to have minimal tensile strength.

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Nd:YAG LB 와 GTA 를 of용한 핵연료봉의 Zircaloy-4 봉단용접특성에 관한 연구 (A Study on the Characteristics of Zircaloy-4 End Cap Welding of Nuclear Fuel Pin Using Nd:YAG LB and GTA)

  • 김수성;이정원;양명승;이영호
    • Journal of Welding and Joining
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    • 제14권6호
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    • pp.81-92
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    • 1996
  • This study is to compare the weldability of Zircaloy-4 end cap of nuclear fuel pin using by GTA and Nd :YAG LB. The welding parameters which affect bead width and penetration depth have been investigated. The effect of joint geometry of end cap for GTAW and LBW has been studied and optimum conditions of Zircaloy-4 endcap welding have been found. Microstructures and microhardness of GTA and LB welded zones have been also compared.

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