The traditional
alloy structural steel is to adjust the content of carbon and alloying elements in the steel and is equipped with appropriate heat treatment to achieve various superior performances, and is used for manufacturing welded structures under different application conditions. However, the general trend is that as the content of carbon and alloying elements increases, the strength increases, the weldability of the steel deteriorates, and the weldability problems of different steel grades vary. In the alloy structural steel, as the content of carbon and alloying elements increases, it tends to cause brittleness, softening and cracking tendency of the joint.
Due to advances in iron and steel smelting and rolling processes, various low-alloy high-strength steels such as building structural steel,
shipbuilding steel plate,
pressure vessel steel, pipeline steel, bridge steel, heat-resistant steel and low-temperature steel all tend to the development of low carbon, ultra-low carbon, micro-alloying, clean, fine-grained direction.
Development of new welding materials for advanced pipeline steel include cellulose down welding rod, low hydrogen iron powder type down welding rod, solid welding wire for gas protection and submerged arc, self-shielded flux cored wire, and welding materials matched with high-strength steel such as fire resistance and weather resistance, etc. The welding materials also include high-strength and high-toughness welding rods, solid welding wire and flux-cored welding wire suitable for high-strength thick plates for large oil storage tanks, pressure vessels, bridges and building structures.