FCAW에 의한 고장력압력용기강의 초층편면용접부 균열에 관한 연구

문성실(Sung-Sil Moon) 산업기술교육훈련학회 2012 산업기술연구논문지 (JITR) Vol.17 No.1

It is well known that solidification cracking often occurs in welds of root pass for one-side welding under the conditions of high welding currents and speeds. In this study, the solidification cracking in SPPV490 was investigated by using FCAW with 4 types of welding wires and welding conditions of 200~280A and 2.8~ 4.2mm/sec. In order to compare the result of cracking in SPPV490, the experiments were also conducted with SWS400 and SM45C as base compared metals. As the results, all the cracks formed in some welding conditions were observed near the center of weld bead. The cracking tendency with bead was extended under the condition of higher welding currents.

FCAW의 혼합가스 변화에 따른 용접 모니터링과 특성에 관한 연구

임병철(Lim, Byung-Chul),강철순(Kang, Chul-Soon),박상흡(Park, Sang-Heup) 한국산학기술학회 2014 한국산학기술학회논문지 Vol.15 No.10

본 연구에서는 Atos 60의 시험편에 혼합가스의 변화에 따른 FCA용접을 하였고, 용접특성 분석 위하여 용접공정상의 실시간 모니터링 시스템과 용접 후 기계적 성질을 평가 하였다. Ar 80%+CO₂ 20% 혼합하고 낮은 속도로 용접한 경우 가장 미려한 비드와 스패터 발생이 적게 나타났으며, 반면 CO₂ 100%인 경우 스패터가 많이 발생하는 것을 확인하였다. 정상단락 이 발생하는 저전류 영역으로 혼합가스의 사용에 대한 스패터 발생을 확인 할수 있는 조건이며, CO₂ 100%인 경우 각층의 단락율은 약 2배 이상 높았고, Peak의 분포가 많은 아크의 불안정 상태로 나타났다. 인장시험결과 Ar 80%+CO₂ 20%, Ar 90%+CO₂ 10%, CO₂ 100%의 항복강도는 각각 511MPa, 507MPa, 469MPa 이었으며, CO₂ 100%의 항복강도 보다 각각 약 8.9% 8.1% 향상되었다. 인장강도는 각각 622MPa, 609MPa, 581MPa로 CO₂ 100%의 인장강도 보다 각각 약 7.0%, 4.8% 향상 되었다. In this study, the effect of varying the mixture gas during FCA welding was studied for an Atos 60 test piece. To examine the characteristics of welding, the weldability of the material was checked before welding and online monitoring was performed to examine the mechanical properties after welding. The mixture Ar 80% + CO₂ 20% at low speed gave very elegant beads with very little spatter. 100% CO₂ gave rise to high spatter generation. For Ar 80% + CO₂ 20%, the low current region due to the normal short circuits created spatter, which was more than double for 100% CO₂. This peak distribution occurred due to the instability of the arc. The tensile test result for Ar 80% + CO₂ 20%, Ar 90%+ CO₂ 10% and CO₂ 100% at 511MPa, 507MPa, and 469MPa showed that the yield strength was improved by 8.1 and 8.9% for 80%+ CO₂ 20% and Ar 90%+ CO₂ 10%, respectively, compared to 100% CO₂. The tensile test result at 622MPa, 609MPa, and 581MPa showed that the yield strength was improved by 7.0% for both the mixture gas compared to 100% CO₂.

FCAW를 이용한 SM45C의 혼합가스비율에 따른 전류파형 및 용접특성 연구

이종훈(JongHun Lee),임병철(ByungChul Lim),박상흡(SangHeup Park) 한국생산제조학회 2014 한국생산제조학회지 Vol.23 No.6

This study, analyzed the waveform and mechanical properties of flux cored arc Welding on SM45C. CO₂ 10% + Ar 90% shows the lowest standard deviation and shunt ratio at which the arc was most stable. CO₂ 10% + Ar 90% is equal to CO₂ 20% + Ar 80%. therefore, CO₂ 20% + Ar 80% is the best of mixture gases. The hardness test result for the gas mixture ratio of CO₂ 10% + Ar 90% was HV 249.7 which is the highest measured value. According to tensile test results, the tensile strength increased with increasing Ar in the mixture gas. This was because of the inertness of the argon, which does not combine with other elements, causing CO₂ to combine with pearlite and ferrite and decreasing the maximum tensile strength. Microstructural examination results show that with increasing Ar, ferrite generation decreases while the mild microstructure increases which influences the hardness.

Flux Cored Wire의 최신 기술 개발 동향

임희대(Hee-Dae Im),최창현(Chang-Hyun Choi),정재헌(Jae-Heon Jung),길웅(Woong Kil) 대한용접·접합학회 2016 대한용접·접합학회지 Vol.34 No.6

Flux Cored Wire is the most widely used welding material for Flux Cored Arc Welding these days. This paper introduces the technical aspects of manufacturing FCW and the development trend of FCW for each type of steel and metal. The studies are ongoing to lower the production cost of seamless-type FCW since it has not been generally used in welding shops so far because of it high cost even though the seamless-type FCW has various advantages than folded-type FCW in terms of manufacturing technology. Meanwhile, a technical research has been carried out to develop a rutile type of FCW products which satisfies high toughness after post heat treatment. In addition, for high-speed fillet welding, there has been a development of welding materials which can be welded in Single Auto-Carriage 100 cpm or more and up to Twin Tandem 200 cpm without occurring any welding defect in order to improve the welding productivity. As Zn coated steel is being used recently to improve the corrosion resistance of the automotive parts, a research and development for Metal Cored Wire has been conducted to reduce the Si island produced in welding operation than those produced when using the former solid wires. A development of welding material that guarantees CTOD performance beyond -40 ℃ CTOD to -60 ℃ is underway by different steel grades, and FCW for super austenitic stainless steel is being developed as the corrosion resistant steel has been upgraded.

Numerical analysis on the welding residual stress and fracture toughness of the heavy thick steel welded joints by welding processes

Bang, HanSur,Bang, HeeSeon The Korean Welding and Joining Society 2015 대한용접·접합학회지 Vol.33 No.2

This study examined the welding residual stress and fracture toughness of 78mm thick steel electro gas welding (EGW) and flux cored arc welding (FCAW) welded joints by numerical analyses of the thermal elasto-plastic behavior and fracture toughness(KIC). The residual stress, fracture toughness characteristics and production mechanism on the welded joints were clarified. Moreover, the effects of the welding process (EGW and FCAW) on the welding residual stresses and fracture toughness of welded joints were evaluated. The results showed that the new welding process (EGW) appears to be an effective substitute for the existing welding process (FCAW) in a thick steel plate with high strength.

Numerical analysis on the welding residual stress and fracture toughness of the heavy thick steel welded joints by welding processes

방희선,방한서 대한용접접합학회 2015 대한용접·접합학회지 Vol.33 No.2

This study examined the welding residual stress and fracture toughness of 78mm thick steel electro gas welding (EGW) and flux cored arc welding (FCAW) welded joints by numerical analyses of the thermal elasto-plastic behavior and fracture toughness(KIC). The residual stress, fracture toughness characteristics and production mechanism on the welded joints were clarified. Moreover, the effects of the welding process (EGW and FCAW) on the welding residual stresses and fracture toughness of welded joints were evaluated. The results showed that the new welding process (EGW) appears to be an effective substitute for the existing welding process (FCAW) in a thick steel plate with high strength.

GMAW 및 FCAW 용접재료 개발 동향

김태훈(Tae-Hoon Kim),박철규(Chul-Gyu Park) 대한용접·접합학회 2017 대한용접·접합학회지 Vol.35 No.6

Welding consumables for arc welding are widely used in various industrial fields. Amongst all processes, the GMAW and FCAW can especially be seen as core processes as they cover approximately 80% in terms of usage. In regards to the FCAW, countless studies are done focusing on the diffusible hydrogen, resulting in developments such as seamless FCW in order to reduce the diffusible hydrogen and the development of welding torch devices that input hydrogen within the shielding gases. Furthermore, countless developments are being made for consumables in the field of construction related fabrications due to the plethora of steel types available and the trend of automation. Developments are also being made according to the automotive industry for the welding of high strength steels and zinc-primered steels.

조선용 극후판 EH36-TMCP강 FCAW 용접부의 역학적 특성에 관한 연구

방한서 ( Han Sur Bang ),고민성 ( Min Sung Go ),김성주 ( Sung Joo Kim ) 조선대학교 공학기술연구원 2009 공학기술논문지 Vol.2 No.3

This work attempts to establish the stability and reliability of welded joint by FCAW for high strength EH32-TMCP ultra thick plate. Experimental results are reported for 37 pass X-groove butt joint of EH32 steel. Abbnevation on Expantion FE analysis has been carried out to simulate the FCA W process on the same specimen model as in experiment. By numerical simulation, thermal and mechanical behavior (residual stress, plastic strain, magnitude of stress and their distribution and production mechanism) has been investigated by heat conduction and thermo elasto-plastic analysis.

오버레이용접된 Wrapping Roll의 비드마크제거를 위한 열영향부의 미세조직에 관한 연구

유국종,백응률 대한용접접합학회 2000 대한용접·접합학회지 Vol.18 No.6

In case of overalyered wrapping roll, beadmark shape appear at wrapping roll surface due to irregular wear between weld bead. Irregular wear of this is caused by difference of hardness between weld bead. This study aims at investigating which matrix is good for removing of beadmark at wrapping roll surface. So, we make specimen with martensitic matrix and austenitic matrix. The overlayered alloys were deposited 4 times on a SS41 steel plate using self-shielding flux cored arc welding method. Difference of hardness between weld bead of specimen with matrix of martensite was higher than specimen with matrix of austenite both as-welded and after heat treatment. Therefore, austenitic matrix is between than martensitic matrix for removing of beadmark of wrapping roll surface.

Variation of Mechanical Properties and Corrosion Properties with Mo Contents of Hyper Duplex Stainless‑Steel Welds

No‑hoon Kim,Woong Gil,Heui‑dae Lim,Chang‑hyeon Choi,Hae‑woo Lee 대한금속·재료학회 2019 METALS AND MATERIALS International Vol.25 No.1

This study investigates the effect of the Mo content on the mechanical and corrosion properties of hyper duplex stainless-steelwelds that are subjected to flux cored arc welding (FCAW). Conventional hyper duplex stainless steel has limited productivityowing to the welding position and welding equipment of gas tungsten arc welding (GTAW) and submerged arc welding(SAW). As such, the purpose of this study is to develop a weld material for FCAW, which is not subject to the limitations ofGTAW and SAW, as well as to improve productivity and quality. FCAW was performed under the same conditions, exceptfor the Mo content, which were varied to 3, 4.5, and 6 wt%. Tensile and impact tests were carried out to investigate thevariation of the mechanical properties according to the Mo content. As the Mo content increased, the elongation decreasedand the strength increased. It was confirmed that the δ-ferrite phase increased and the γ-austenite phase decreased as theMo content increased. Secondary phase such as σ phase, χ phase were mainly distributed in ferrite grains or austenite–ferritegrain boundaries using EBSD. It was also increased as the Mo content increased. To evaluate the corrosion resistance,Potentiodynamic Polarization Tests and DL-EPR tests were conducted. As a result, all of specimens showed similar corrosionresistance.