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오스테나이트계 스테인리스강 FCW 오버레이 용접 시 입열량에 따른 조직변화와 굽힘균열 특성
임희대 ( Hee Dae Im ),길웅 ( Woong Kil ),신기삼 ( Keesam Shin ),구본흔 ( Bon Heun Koo ) 대한금속재료학회(구 대한금속학회) 2013 대한금속·재료학회지 Vol.51 No.4
This study investigated the effect of heat input in overlay welding using stainless steel FCW on the dilution ratio and characteristics of microstructural evolution, initiation and propagation of a bending crack in the overlay weldment. When the heat input was varied in the range of 3.2-19.8 kJ/cm by adjusting welding parameters such as current, voltage and speed, the dilution ratio was the highest in 7.9- 9.9 kJ/cm with the lowest values of Creq and Nieq, for which the formation of martensite was predicted by the Schaeffler diagram, and its existence was confirmed by optical microscopy. In addition, the width of the transition zone was the largest in heat input of 7.9-9.9 kJ/ cm, and martensite was observed in the transition zone of the first weld layer of E309LT1-1 (welding material) and ASTM A516 Gr.70 (base metal). According to the bending test, cracks were observed in the specimens with heat input of 8.6-9.5 kJ/cm.
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.
산소분압열처리를 이용한 폐기물산화철로부터의 단상 및 복합상 산화철의 제조
임희대,이찬규,허석환,박연준 國立 昌原大學校 産業技術硏究所 1998 産技硏論文集 Vol.12 No.-
Oxygen pressure heat-treatment with CO-CO2 gas mixture was introduced to purify the waste oxidized iron in shortblast process. To determine the temperture and oxygen partial pressure, Fe-O phase diagrams was used. single phase FeO, Fe₃O₄and composite phase FeO-Fe₃O₄, Fe-FeO could be obtained sucessfully in the range of 10(-17)∼10(-19) in Po₂at 800℃.