Research for the Optimal Flux-Cored Arc Welding Process of 9% Nickel Steel Using Multi Object Optimization with Solidification Crack Susceptibility

Abstract

The environment of the global shipbuilding market is changing rapidly. Recently, the International Maritime Organization (IMO) has tightened regulations on sulfur oxide content standards for marine fuels and tightened sulfur oxide emission standards for the entire coastal region of China to consider the environment globally and use LNG as a fuel. There is a tendency for the number of vessels to operate to increase significantly. To use cryogenic LNG fuel, various pieces of equipment, such as storage tanks or valves, are required, and equipment using steel, which has excellent impact toughness in cryogenic environments, is required. Four steel types are specified in the IGG Code, and 9% Ni steel is mostly used for LNG fuel equipment. However, to secure safety at cryogenic temperatures, a systematic study investigating the causes of quality deterioration occurring in the 9% Ni steel welding process is required and a discrimination function capable of quality evaluation is urgent. Therefore, this study proposes a plan where the uniform quality of 9% Nickel steel is secured by reviewing the tendency of the solidification crack susceptibility among the quality problems of cryogenic steel to establish the criteria for quality deterioration and to develop a system capable of quality discrimination and defect avoidance.

A Study on the Weldment Hardening Discrimination Procedure and Improvement of Flux Cored Arc Welding Process of ASTM A553-1 (9% Nickel Steel) Material Using Bead Geometry Distribution

“…Naturally, the previous studies are similar to past research [7]. Yun [8] performed the optimization of fillet laser welding for 9% Ni steel, and Na [9] compared GTAW and FCAW for 9% Ni steel.…”

“…The response surface analysis method is a statistical analysis method for the response surface formed by the change of response when several input variables x 1 , x 2 , x 3 , • • • x k have an effect on the output variable y through complex actions. This procedure was carried out in the previous research [7].…”

“…The MOO (multi-objective optimization) algorithm to be applied in this study is a technique used to search for non-dominant solutions. This process is derived in previous research [7,[28][29][30]. The program schematic diagram of the MOO optimization method is shown in Figure 10, and MATLAB, which is a commercial numerical analysis program, was used to apply and modify the optimization method.…”

“…This study was related the previous research which evaluated the weldability with solidification crack susceptibility [7], and used similar evaluating methods such as welding test and optimization. However, it focused on weldment hardening as an evaluating method differently.…”

Effect of Temperature on Microstructure and Mechanical Properties of Fe-9Ni-2Cu Steel during the Tempering Process

“…The development of the global new energy industry, the adjustment of the domestic energy structure, and the increase of environmental protection pressure have led to a sharp increase in the demand for natural gas, so it is necessary to increase the quality of vehicles for natural gas. 9Ni steel with high strength and high low-temperature toughness has attracted a great deal of attention over the past few years [ 1 , 2 , 3 , 4 , 5 , 6 ].…”