A kind of welding wire and flux for submerged arc welding of 9ni low temperature steel and its application

Abstract

The invention discloses a welding wire and a welding flux for 9Ni low-temperature steel submerged arc welding as well as application of the welding wire and the welding flux. The welding wire comprises the following chemical ingredients in percentage by weight: at most 0.04 percent of C, at most 0.10 percent of Si, at most 0.10 percent of Mn, 15 to 25 percent of Mo, 2.0 to 6.0 percent of W, 0.10 to 0.50 percent of Al and the balance of Ni and inevitable impurities. The welding flux comprises the following ingredients in percentage by weight: 5 to 20 percent of Ti2O3, 15 to 35 percent of MgO, 15 to 35 percent of CaF2, 15 to 25 percent of A12O3 and the balance Na2O, and the alkalinity is 2.2 to 4.2. The welding wire and the welding flux are adopted, submerged arc weld metal with excellent comprehensive performance can be obtained, the yield strength of the weld metal is greater than or equal to 516MPa, the tensile strength is greater than or equal to 725MPa, the impact power at minus 196 DEG C is greater than or equal to 90J, and the CTOD (crack tip opening displacement) displacement value at minus 196 DEG C is greater than or equal to 0.58mm. The welding wire and the welding flux can provide solutions for the welding assembly of LNG (liquefied natural gas) low-temperature storage tanks in China.

Description

technical field [0001] The invention relates to a submerged arc welding wire and flux for low-temperature steel, in particular to a submerged arc welding wire and flux for 9Ni low-temperature steel, and belongs to the field of matching welding materials for low-temperature steel. Background technique [0002] With the increasing demand for liquefied natural gas (LNG), 9Ni steel has been generally accepted as the steel for its storage tanks, and the storage tank structure is constantly developing in the direction of large-scale. The welding of 9Ni low-temperature steel is one of the key points and difficulties in the construction of LNG low-temperature storage tanks. [0003] The submerged arc welding method is widely used in the horizontal and longitudinal seam welding of LNG storage tanks due to its advantages of high degree of automation, controllable welding quality, and high welding efficiency. At present, the grades of submerged arc welding wire widely used are mainly ...

AI Technical Summary

Problems solved by technology

However, the existing submerged arc welding wire and flux are designed for horizontal welds and cannot be used for vertical welds. On the one hand, the welds are not well formed, resulting in poor quality of welded joints; on the other hand, the strength and low temperature toughness of the weld metal It is also difficult to meet the actual needs

Images