• Title, Summary, Keyword: Heat Input

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An observer design for the superheater temperature estimation (과열기의 온도추정을 위한 관측기의 구성)

  • 서진헌;황재호;이상혁
    • 제어로봇시스템학회:학술대회논문집
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    • pp.101-106
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    • 1990
  • The problem of constructing an observer for use in the control of superheater temperature with desuperheater is considered. The distributed heat input into the superheater is usually not available for use in the observer, and hence is treated as a disturbance. The observer theory for systems with unknown inputs is exploited and applied to the problem. Approximation of the heat input utilizing the specific heat input distribution pattern is also considered.

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The characteristics of bead welding on steel with process parameter during the laser-arc hybrid welding(II) - Effect of heat input parameters - (강의 레이저-아크 하이브리드 용접시 공정변수에 따른 비드용접특성 (II) - 용접 입열 변수의 영향 -)

  • Kim, Jond-Do;Myung, Gi-Hoon;Park, In-Duck
    • Journal of Welding and Joining
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    • v.33 no.2
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    • pp.91-96
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    • 2015
  • The laser-arc hybrid welding of SS400 steel was carried out with the use of disk laser equipment of 6.6kW maximum power and MAG equipment of pulse mode. Parameter regarding heat input is one of the most important factors that directly affect penetration characteristics and welding defect. Therefore in this study, the effects of laser power, welding speed and current, voltage and pulse correction were investigated. As experiment result, it was found that the lower heat input, the more likely humping bead is formed at the back, and such humping bead could be suppressed by increasing laser power and arc current or decreasing welding speed, thus increasing heat input. Also deep penetration could be achieved by reducing arc voltage or pulse correction parameter in the same welding condition.

A Study on the Formation of Cavity and Welding Property in the Laser Welding Fusion Zone between Sintered Segment and Mild Steel Shank (소결체와 저탄소강의 레이저용접시 생성되는 캐비티의 형성과 용접 특성에 대한 연구)

  • Cho Nam-Joon;Jung Woo-Gwang;Kim Sung-Wook;Lee Chang-Hee;Kim Sung-Dea
    • Korean Journal of Materials Research
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    • v.14 no.4
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    • pp.300-306
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    • 2004
  • A laser welding has been made between sintered tip of Fe-Co-W and low carbon steel shank for the diamond saw blade. The welding characteristics and formation of defect has been investigated carefully for the weld fusion zone in different welding condition. Full penetration has been observed for the whole range of heat input investigated in the present work. Bead width and under-fill have been increased with the increase of heat input. With increasing of heat input small cavities were decreased while large cavities were increased. The ratio of total cavity area to the entire weld bead area was not changed significantly with change of heat input. Most of cavities were found near the tip, and supposed to be formed from the pore in the tip.

Effect of Heat Input on the Mechanical Properties of SA508 class 3 Steel Weldments with Submerged Arc Welding (SA508 class 3 서브머지드 아크용접부의 기계적 성질에 미치는 입열량의 영향)

  • Seo Yun-seok;Koh Jin-Hyun;Kim Nam-Hoon;Oh Se-Yong;Choo Kee-Nam
    • Journal of Welding and Joining
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    • v.22 no.5
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    • pp.38-45
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    • 2004
  • The present study is to investigate the effect of heat input on the microstructure, tensile properties and toughness of single-pass submerged arc bead-in-groove welds produced on SA508 class 3 steels. The heat input was varied in the range of 1.6, 3.2 and 5.0 kJ/mm. The toughness of weld metals was evaluated by using subsize Charpy V-notch specimens in the temperature range of -19$0^{\circ}C$ to 2$0^{\circ}C$. The weld microstructure and fractography were observed by optical and scanning electron microscopies, respectively. With increasing heat inputs, tensile strength and hardness of weld metals were decreased while elongation was increased. The poor notch toughness at 1.6 kJ/mm was attributed to the formation of ferrite with aligned second phase and banitic microstructure with high yield strength while that at 5.0 kJ/mm was due to the presence of grain boundary and polygonal ferrites. The microstructure of the intermediate energy input welds consisted of a high proportion of acicular ferrite with limited polygonal ferrites, which provide improved notch toughness.

A Study on Microstructure and Thoughness of Electrogas Weldments (일렉트로가스 용접부의 조직 및 인성에 관한 연구)

  • 이해우;장태원;이윤수;석한길;강성원
    • Journal of Welding and Joining
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    • v.14 no.1
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    • pp.68-74
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    • 1996
  • The microstructure of HAZ and the mechanical properties in weldments such as hardness and toughness were studied for mild steel and AH36 grade TMCP steel, as increasing heat input with electrogas welding process. The results of this study can be summarized as follow: 1) In the HAZ of mild steel, the width of coarse grained zone was larger than that of the nomalized zone, however in the case of TMCP steel, the nomalized zone was wider than the coarse grained zone. 2) The grain size of HAZ become coarse with increasing heat input. And at the same heat input, the grain size of TMCP steel was more coarser than that of mild steel. 3) According to the change of heat input, the deviation of hardness values was not significant, and the maximum values of hardness was not in HAZ but in the weld metal. And the hardness values in root part was higher than in face part. 4) Even though the HAZ grain size of mild steel was larger than that of TMCP steel, the impact values for mild steel was higher than those for TMCP steel, and the impact values in face part was higher than those in root part.

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A Study on Grooving Corrosion at the Weld of a Low Carbon Steel Pipe Made by Electrical Resistance Welding (탄소강관의 ERW 용접부 홈부식 손상에 관한 연구)

  • Kim Yong;Lee Bo-Young
    • Journal of Welding and Joining
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    • v.22 no.5
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    • pp.58-64
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    • 2004
  • Although leakage at a low carbon steel pipe made by electrical resistance welding (ERW) was reported due to grooving corrosion, the cause for the corrosion has not yet been cleared. In order to clarify the main cause, failure analysis on the leaked pipe was carried out, followed by metallographic investigation and corrosion test for the various ERW pipe made with different welding heat input. The microstructure, particularly inclusion content, of the weldment is dependant on the welding heat input applied. For an improper low heat input, the amount of inclusion at the weld was high. High inclusion content accelerated grooving corrosion at the weld. It is therefore that welding heat input should be controlled based on the carbon content of the pipe in order to improve the corrosion resistance of the ERW pipe.

Effect of heat input on the strength & micro-fissuring of alloy 59 weld (용접입열이 Alloy 59 용접부 강도와 미세균열에 미치는 영향)

  • Choe, Jun-Tae;Kim, Yeong-Il;Kim, Dae-Sun
    • Proceedings of the KWS Conference
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    • pp.165-167
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    • 2005
  • Compared with Inconel 625 (ERNiCrMo-3) weld, Nb-free Alloy 59 (ERNiCrMo-13) weld with 15% Mo showed much higher resistance to hot cracking. Especially in the condition of current 350A and 30CPM of welding speed, no crack was detected at Inconel 625 fillet weld. Furthermore, it was found that the strength of Alloy 59 is sensitive to welding heat input. Up to around 14kJ/cm of heat input, Alloy 59 showed 678N/$mm^{2}$ of ultimate strength and 466N/$mm^{2}$ of yield strength. However, as heat input increased above 14kJ/cm, Alloy 59 weld could not satisfy the weld strength required for European LNG tank.

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Application of high heat input(wider bead width) for hull structural welding with semi-automatic FCAW (선체 반자동 FCAW 적용 시, 대입열(비드폭 확대) 용접 적용)

  • Nam, Seong-Gil;Jang, Tae-Won;Yun, Dong-Ryeol;Han, Jeong-Seok
    • Proceedings of the KWS Conference
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    • pp.142-143
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    • 2006
  • The use of hull structural steel with heavy thickness has been enlarging due to the increase of ship volume. High heat input welding methods like EGW, FGB and SAW tandem are applied in field of ship-building. However the application of high heat input methods is clearly limited because welding method to be most widely used is semi-automatic FCAW but heat input for FCAW is limited in order to obtain impact property at low temperature. This paper will introduce the application of 30mm bead width of FCW with Ni free & low Ni content.

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Evaluation of Fracture Toughness and Microstructure on FCA Weldment According to Heat Input (입열량에 따른 FCAW용접부 파괴인성에 미치는 미세조직의 영향)

  • Shin, Yong-Taek;Kang, Sung-Won;Kim, Myung-Hyun
    • Journal of Welding and Joining
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    • v.26 no.3
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    • pp.51-60
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    • 2008
  • This paper is to evaluate fracture characteristics of API 2W Gr.50 TMCP steel weldment typically applied for offshore structures, with the focus on the influence of heat input arising from flux cored arc welding. Based on the results and insights developed from this study, it is found that the toughness for both CTOD and impact exhibits a tendency to decrease as the weld heat input increases. The reheated zone of weldmetal exhibit lower hardness than solidified zone and microstructure that are liable to affect the toughness are acicular ferrite and martensite-austenite constituents (M-A). In particular, M-A is a more effective micro-phase for CTOD toughness than impact toughness.

Study on the Heat Generation Characteristics of the Carbon Heating Source with High Temperature (고온 카본발열체의 발열특성에 관한 연구)

  • Bae, K.Y.;Lee, K.S.;Shin, J.H.;Jeong, H.M.;Chung, H.S.;Chun, J.S.
    • Proceedings of the KSME Conference
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    • pp.106-111
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    • 2001
  • This paper is a study on the heat generation characteristics of the carbon heating source with high temperature. The main variables of this study are the input current and the amount of carbon heating source. As the results of the experiment in the waste rate of carbon heating source. The case of carbon heating source 300g was large than 500g. As the input current and the temperature are increased, the resistance values of carbon heating source were large. The Joule heat was represented the large value as the amount of heating source decrease with the input current. Finally, the heating source was represented the electrical steady state as the input current is increase.

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