Ultralow temperature steel nickel-based welding rod with core wire added with rare earth element and preparing method thereof

Abstract

The invention relates to an ultralow temperature steel nickel-based welding rod with a core wire added with the rare earth element. The ultralow temperature steel nickel-based welding rod is formed by the core wire and a coating wrapping the surface of the core wire, the content of the rare earth element in the core wire ranges from 0.01% to 0.20% by weight, the rare earth element is at least one of Ce, Y and Nd, and the other components include, by weight, 55.0%-70.0% of Ni, 15.00%-19.00% of Cr, 4.50%-8.00% of Mo, 2.50%-4.50% of Mn, 1.50%-5.0% of Fe, 1.00%-3.00% of Nb, 0.50%-1.50% of W, 0.10%-0.30% of Cu, 0.20%-0.50% of Si and not larger than 0.05% of C. The invention further provides a preparing method of the above welding rod.

Description

technical field [0001] The invention belongs to the field of welding materials, in particular to a nickel-based welding rod for ultra-low temperature steel and a preparation method thereof. Background technique [0002] With the rapid development of my country's petrochemical industry and energy industry, cryogenic storage tank equipment for liquid nitrogen and liquefied natural gas (LNG for short) has also been greatly developed. The working environment temperature of large LNG cryogenic storage tanks can be as low as -196°C, and it needs to bear a lot of pressure and the working environment is relatively harsh. 9Ni steel is an ultra-low temperature nickel-based alloy steel plate that still has good low-temperature impact toughness, high strength and corrosion resistance when used at a low temperature of -196°C. Its mechanical properties are: tensile strength: 680-820Mpa, yield strength ≥ 570Mpa, elongation A≥20%, -196°C impact value ≥100J, and has the advantages of less a...

AI Technical Summary

Problems solved by technology

During the welding process of this kind of electrode with rare earth elements added to the coating, since the coating is in direct contact with the air, the rare earth elements in the coating are easily oxidized and consumed, and the deposited metal obtains rare earth elements by absorbing the coating. The rare earth elements in the skin will inevitably lead to low absorption efficiency and unstable absorption of rare earth elements by the deposited metal, and cannot guarantee the content and accurate control of the content of rare earth elements in the deposited metal, so the performance of the deposited metal cannot be effectively guaranteed

[0004] On the other hand, in the actual welding process of the above-mentioned 9Ni steel electrode, the welding line energy is generally less than 20KJ / cm. If the welding line energy is too large during the welding process, liquid cracks and coarse grains of the structure will easily occur in the weld, resulting in a Hot cracking and weld toughness decrease, which are not allowed in large LNG cryogenic storage tanks

Therefore, it is difficult to increase the welding line energy, but the small welding line energy will increase the number of welding passes, reduce the welding efficiency, and greatly reduce the production efficiency