9% Ni강의 Super-TIG용접에서 용입에 미치는 용접 변수의 영향

Abstract

Recently, the International Maritime Organization(IMO) has tightened its regulations to reduce sulfur oxides (SOx) emissions from ships, limiting it to 0.5% since January 2020. As a result, the use of clean fuels(LNG), such as liquefied natural gas, is expanding worldwide and the demand for LNG storage tanks and LNG fuel tanks is increasing. For LNG storage tank and LNG fuel tank manufacturing, steel that satisfies low-temperature toughness at -196 ℃ is used, and Inconel 625 wire or Hastelloy-based wire is used as the welding material. Suitable welding methods for 9% Ni steel include FCAW, SAW, and TIG welding. In industries where high-quality welding is required, a spatter and fume-free TIG welding process is essential. In TIG welding, filler feeding speed, welding speed, and welding current can be controlled separately. In order to improve the productivity of TIG welding, it is necessary to increase the feed speed of the filler and the welding current. The use of high welding currents can cause defects by causing high indentation on the melt pool surface due to the high arc pressure generated by the plasma stream. Therefore, in order to solve the above problems, it is necessary to observe the relationship between welding current and penetration under high welding speed conditions.

In this study, the Penetration governing parameter(PGP) was made to predict the penetration during welding using Inconel 625 C-Filler in the super-TIG welding of 9% Ni steel.