• Title, Summary, Keyword: FCAW

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The influence of post weld heat treatment on mechanical properties of stainless steel weldment (스테인리스강 용접부의 기계적 성질에 미치는 후열처리의 영향)

  • 한종만;한기형;이은배;허만주;한용섭
    • Journal of Welding and Joining
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    • v.14 no.3
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    • pp.75-85
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    • 1996
  • In this paper the influence of postweld heat treatment on mechanical properties of SMAW and FCAW stainless steel weldments was examined and the obtained results are as follows ; (1) The amount of $\delta$-ferrite formed by SMAW and FCAW process decreased with increasing holding temperature and time in post weld heat treatment(PWHT), and it was found that the reduced ferrite was transformed into sigma phase after $800^{circ}C{\times}50hr$ PWHT. This sigma phase, even though it was very small, resulted in brittleness of dissimilar weldment between carbon steel and stainless steel in bending test, however in similar weldment between stainless steel and stainless steel was not occured. (2) The chemical composition of sigma phase was measured to 28-30%Cr, 7-9%Mo, 4-6Ni in 316L weldment, and also 35-37%Cr, 0.9-1.0Mo, 6-8%Ni in 309L weldment by EDS analysis.

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A Study on the Development of Arc Sensor for Flux Cored Arc Welding Process and its Application for Seam Tracking (Flux Cored Arc용접용 아크센서의 개발 및 이를 이용한 용접선 추적에 관한 연구)

  • 김수영;이승영;나석주
    • Journal of Welding and Joining
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    • v.10 no.4
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    • pp.190-198
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    • 1992
  • Among the variety of welding processes available, the flux cored arc welding is one of the most frequently used process, because of its wide range of application and high productivity. The weld joint tracking is indispensable to improve the flexibility of the arc welding robot application for the flux cored arc welding (FCAW) process. In this study, an arc sensor which utilizes the electrical signal obtained from the welding arc itself was developed for weld joint tracking in FCAW. Because a model of the welding arc in flux cored arc welding was required to develop the arc sensor, a mathematical model was proposed by analysing the welding arc behaviour, and also an experimental model by using the factorial experiment and least square method. For overcoming the fluctuation in the welding current signal during tracking the weld joint, it was fitted to a curve which is inversely proportional to a trace of tip-to-workpiece distance by using the quadratic curve-fitting method.

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An Analysis of the Cause of Porosity Generation and Reduction Plan in Fillet Welding (필렛용접에서의 결함발생 원인 분석 및 저감 방안)

  • Choi, K.Y.;Kim, Y.P.;Kim, K.J.;Kim, D.S.;Bae, S.D.
    • Special Issue of the Society of Naval Architects of Korea
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    • pp.128-133
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    • 2006
  • Generally, porosity which was formed by pyrolysis of the primer is usually generated in the weld metal in respect of increase of the welding speed. in order to analyze the cause of porosity generation, this study was performed using FCAW(flux cored arc welding) process for three kinds of inorganic.zinc primer. in addition the evaluation by influence of welding method on porosity generation is conducted to compare between FCAW and MAG(metal active gas) welding with the same inorganic zinc primer. As the result of this investigation, not only primer of lower organic binder and zinc but also FCAW process than MAG in fillet welding have been verified the excellent resistance to the porosity generation for horizontal fillet welding.

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A Study of the Residual Stress Characteristics of FCAW Multi-Pass Butt Joint for an Ultra-Thick Plate (극후판 다층 FCAW 맞대기 용접부의 잔류응력 특성에 관한 연구)

  • Bang, Hee-Seon;Bang, Han-Sur;Lee, Yoon-Ki;Kim, Hyun-Su;Lee, Kwang-Jin
    • Journal of Ocean Engineering and Technology
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    • v.24 no.2
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    • pp.62-66
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    • 2010
  • The goal of this work is to establish the reliability of FCA welded joints for high strength EH36-TMCP ultra thick plate. For this, heat conduction and thermo elasto-plastic analyses have been conducted on a multi-pass, X-groove, butt-joint model to clarify the thermal and mechanical behavior (residual stresses, magnitude of the stresses, and their production and distribution mechanisms) of the weld joint. In addition, the results of the welding residual stress obtained from thermo elasto-plastic analysis was verified and compared with results obtained by XRD analysis.

Quantitative Analysis on the Effects of Welding Parameters on Diffusible Hydrogen Contents in Weld Metal Produced by FCAW Process (FCAW에서 용접금속 확산성수소량에 미치는 용접변수 영향의 정량적 해석)

  • Han, Dong-Woo;Bang, Kook-Soo;Jeong, Hong-Chul;Lee, Jong-Bong
    • Journal of Welding and Joining
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    • v.28 no.2
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    • pp.54-59
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    • 2010
  • The effects of welding parameters such as contact tip-to-work distance (CTWD), voltage, and current on the weld metal diffusible hydrogen contents (HD) were investigated and rationalized by the calculation of heating time and amount of heat generated in the extension length of flux cored wire. As CTWD increased from 15 to 25mm, HD decreased from 8.46 to 5.45mL/100g deposited metal. Calculations showed that, with an increase of CTWD, the amount of heat generated increased from 46 to 92J in addition to an increase of heating time. Increase of current from 250 to 320A, however, gave little variation of HD. It showed that no significant change in the amount of heat generated was found, and heating time was decreased with an increase of current. It also showed that CTWD is more influential than voltage in relatively lower heat input ranges, while voltage is more in higher input ranges

Explosion Bulge Test in Underwater of 800MPa Grade Pre-Heat Free Welding Plate (800MPa급 무예열 용접 판재의 수중 폭파변형시험)

  • Park, Tae-Won;Song, Young-Bum;Kim, Jin-Young;Yang, Seong-Ho;Hong, Sung-Suk;Shim, In-Ok;Park, Chul-Kyu;Kim, Hee-Jin
    • Proceedings of the KWS Conference
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    • pp.63-63
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    • 2010
  • The pre-heat free consumables for GMAW, SAW and FCAW processes that matches the Cu-bearing PFS-700 steel which has yield strength over 700MPa were developed and evaluated to see the suitability in military such as submarine and battle ship. Explosion bulge test in underwater was developed and applied to see the reliability of welded structure. All welding was conducted without pre-heat before welding, the interpass temperature was below $150^{\circ}C$ for all welding conditions. Tensile strength for the weld metal in GMAW, SAW and FCAW process is 887MPa, 875MPa and 813MPa, respectively, these values are similar to the base metal of PFS-700 steel of 838MPa. EBT results in GMAW, SAW and FCAW show 14.0%, 14.02% and 15.9% reduction of thickness without generation of crack, respectively and stand-off distance was set up properly to have over 14.0% reduction of thickness. Through EBT results, the developed new consumables are applicable to the weapon systems such as submarine and battle ship.

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A Study on High Temperature Tensile Property of Inconel 625 for Petroleum Application by Flux cored Arc Welding Process (석유시추용 인코넬 625강의 FCAW용접에 의한 고온인장 특성에 관한 연구)

  • PARK KEYUNG-DONG;AN DO-KEYUNG;JIN YOUNG-BEOM
    • Proceedings of the Korea Committee for Ocean Resources and Engineering Conference
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    • pp.352-355
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    • 2004
  • Inconel 625 is useful in variety of industrial applications because of the resistance to attack in various corrosive media at temperatures from $200^{\circ}C$ to over $1090^{\circ}C$, in combination with good law- and high temperature mechanical strength. Rencently, this material is also used widely in offshore processing piping in order to extend the maintenance tenn and improve the quality of anti-corrosion. In general, high quality weldments for this material are readily produced by commonly used processes. Not all processes are applicable to this material group, Ni-alloys. Metallurgiad characterictics or the unavailability of matching, position or suitable welding processes. Nowadays, the flux cored wire is developed and applied for the better productivity in several welding position including the vertical position. in this study, the weldability and weldment characteristics of inconel 625 are considered in FCAW weld associated with the several shielding gases($80\%Ar\;+\;20\%\;CO_2,\;50\%Ar\;+\;50\%\;CO_2,\;100\%\;CO_2$) in viewpoint of welding productivity.

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A Study on the Fracture Toughness Characteristics of FCAW Weldment of Steel for Offshore Structures (해양 구조물용 강재 FCAW 용접부의 파괴인성 특성에 관한 연구)

  • Kang Sung-Won;Kim Myung-Hyun;Kim Yong-Bin;Shin Yong-Taek;Lee Hae-Woo
    • Journal of Welding and Joining
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    • v.22 no.6
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    • pp.57-63
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    • 2004
  • Fracture toughness is an important parameter in designing offshore structures to ensure resistance to fracture at various temperatures. In this study, a series of experiments is carried out to obtain fracture toughness values (CTOD) of API 2W Gr.50B, welded using FCAW(Flux Cored Arc Weld). In particular, a comparison of absorbed impact energy and CTOD values are made with respect to two different welding groove shapes; double-V-groove and double-bevel-groove. Charpy impact tests are performed for specimens sampled near the root gap, and CTOD tests are carried out for three point bending specimens having the notch at weld zone. While Charpy impact test result is determined to be a good qualitative measure of fracture toughness, no quantitative correspondence between impact absorbed energy and CTOD values was found. Based on the experiment, it is observed that double-V-groove welds give lower transition temperature than those of double-bevel-groove.

A Study on the Fatigue Crack Growth Characteristics of the Welded Part According to the Welding Method of Ship Structural Steel (선체구조용강의 용접방법에 따른 용접부의 피로균열전파특성 연구)

  • Park, Kyeong-Dong;Ki, Woo-Tae;Lee, Ju-Yeong
    • Journal of the Korean Society of Marine Engineering
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    • v.31 no.4
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    • pp.385-393
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    • 2007
  • The strength evaluation of the most weakest junction part is required for the safety design of all structures. Most of all. in order to enhance the reliability and safety of the welding part. whose use is the highest, it is very important to establish the efficient structure manufacturing technology by studying and investigating the evaluation of fatigue strength in various environments. This study analyzed the relations of da/dN, and th according to the welding methods of SMAW, FCAW, and SAW. In the stage II. the value of stress intensity factor range was the highest in SMAW welding method of stress ration R=0.1, and appeared under the sequence of FCAW and SAW and as the completion section of stress intensity factor was low, threshold stress intensity factor was lowly formed in da/dN - The fatigue life of each welding method is sensitively worked in high stress ratio. judging from the fact that the width of life reduction increases in the high stress ratio zone compared to the width of life reduction in the low stress ratio zone. In the fatigue limit of welding methods before corrosion. the welding of SMAW and FCAW shows the same fatigue limit compared to Base metal, and SAW holds the lowest fatigue limit value.

Explosion Bulge Test Underwater of 800MPa Grade Pre-heat Free Welding Plate (800MPa급 무예열 용접 판재의 수중 폭파변형시험)

  • Park, Tae-Won;Song, Young-Beum;Kim, Jin-Young;Yang, Sung-Ho;Park, Chul-Gyu;Seo, Jun-Suck;Kim, Hee-Jin
    • Journal of Welding and Joining
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    • v.28 no.6
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    • pp.63-69
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    • 2010
  • The pre-heat free consumables for GMAW, SAW and FCAW processes that matche with the Cu-bearing PFS-700 steel which has yield strength over 700MPa were developed and evaluated to see the suitability in military such as submarine and battle ship. Explosion Bulge Test underwater was developed and applied to see the reliability of welded structure. All welding was conducted without pre-heat before welding, the interpass temperature was below $150^{\circ}C$ for all welding conditions. Tensile strength for the weld metal in GMAW, SAW and FCAW process is 887MPa, 875MPa and 813MPa, respectively, these values are similar to the base metal of PFS-700 steel of 838MPa. EBT results in GMAW, SAW and FCAW show 14.0%, 14.02% and 15.9% reduction of thickness without generation of crack, respectively and stand-off distance was set up properly to have over 14.0% reduction of thickness. Through EBT results, the developed new consumables are applicable to the weapon systems such as submarine and battle ship.