Mechanical and Microstructural Behaviors of Gas Tungsten Arc Dissimilar Metal Welds of High-Mn Steel and Stainless Steel 316L Using Various Fillers for Cryogenic Fuel Tanks

Abstract

The gas tungsten arc (GTA) weldability of high-Mn (HMn) steel and austenitic stainless steel (STS) 316L using dissimilar metal welds (DMWs) was investigated, to fabricate a fuel tank for an LNG-fueled ship. Three types of welding fillers, HMn steel, STS 309LMo and Inconel 625, were applied to the DMWs. The weldability of the DMWs was examined by investigating mechanical properties at 25 and -196 o C, followed by microstructural evolution and weld deformation. The GTA welding process was performed with a heat input range of 0.72–1.89 kJ/mm. All of the fillers employed in the study produced reasonable mechanical properties and low levels of precipitation, such as M<sub>7</sub>C<sub>3</sub> and Fe<sub>3</sub>C. However, the DN specimen using the Inconel 625 filler exhibited reduced ductility in the bending test. This was attributed to Nb-carbide precipitations at dendrite boundaries at the root weld. The DM specimen using HMn filler experienced severe thermal deformation because it had a relatively higher coefficient of thermal expansion than the other fillers during heating by arc and solidification. Therefore, STS 309LMo and HMn wires were determined to be the appropriate fillers for the DMW of HMn steel and STS 316L for cryogenic applications, and the HMn wire requires attention to weld deformation.

A Study on the Relationship between Microstructure and Impact Toughness with Different Heat Inputs and Post-Seam Annealing Temperatures in API X70 Electric Resistance Welded Steel Pipe

“…전 세계적으로 천연자원의 수요 증가에 따른 공급확대를 위해 극저온에 노출되거나 황화수소(H 2 S)가 다량 함유된 sour 환경까지 자원채굴 영역이 확장되면서 이러한 환경에 서 대응할 수 있는 파이프 소재의 특성 요구가 점차 강화 되고 있다 [1][2][3][4]. 소재가 극한의 환경에 적용되기 위해서는 sour 환경의 경우 H 2 S로 인한 수소 유기 균열(Hydrogen Induced Cracking, HIC) 및 응력부식균열에 대한 저항성, 극저온 환경의 경우 우수한 저온충격인성이 요구된다 660 대한금속 • 재료학회지 제61권 제9호 (2023년 9월) [2,3,[5][6][7]. 천연가스와 석유의 수송을 위한 소재로는 원거리 에서도 저비용으로 효과적인 수송이 가능한 라인파이프강 이 적용되고 있으며 [7,8], API(American Petroleum Institute) 5L 규격을 따른다 [9].…”

The Effects of Post-Weld Heat Treatment on the Microstructure and Mechanical Properties of 9% Ni Steel Weld Joint with Fe-Based Filler Material

“…이에 따라, LNG 운송 및 보관을 위해 사용 되는 저장탱크는 상온 뿐만 아니라 극저온 환경에서도 우 수한 기계적 특성 및 인성을 가지는 소재 적용을 요구한다 [1][2][3][4][5][6]. 금속 소재 중 면심 입방정 구조 (face centered cubic, FCC)를 가지는 합금은 극저온 환경에서 우수한 물 성의 제공하여, LNG 저장을 위한 탱크 재료로 주로 활용 된다 [1,[7][8][9][10][11][12][13][14]. 구체적으로는 고망간강 [1,[10][11][12], 인바 (Invar) 합금 [2,13], A5083 알루미늄 합금 [3], FCC계 고엔트로피 (high entropy alloy) 합금 [4]과 변태유기소성 (transformation induced plasticity, TRIP)강인 오스테나이 트계 스테인리스강 [5,14]과 9% Ni강 [6] 등의 재료가 활 용되었다.…”

Weld Zone Analysis Based on FCAW Mechanical Characteristics and Heat Transfer Analysis of 316L Stainless Steel for Liquefied Hydrogen Tanks

“…Cho et al performed heterogeneous butt welding of 20 mm thick 316L and high manganese steel materials with GTAW using different types of filler metals. The resulting welds were compared and analyzed using mechanical testing and microstructure observation at room and cryogenic temperatures [ 19 ]. Ha et al performed BOP welding through fiber laser welding on ASTM-A240M-304, with ASTM-A240M-304 materials under different welding conditions.…”