Core-spun wire technology is the simplest and most effective method for deoxidizing, desulfurizing and modifying molten steel, as well as alloying, microalloying, fine-tuning of alloy composition, refining grains, and improving the castability, toughness and workability of steel. The practice has proven that compared with the traditional block throwing method or flushing method, the cored wire method for molten steel treatment has the following advantages:
1. The method of adding aluminum wire to the molten steel for the final deoxidation of molten steel can save 50% to 70% of the consumption of aluminum, and the residual aluminum content in the molten steel can be stabilized at a very small range like 0.025% or 0.035%.
2. The method of adding silicon-calcium alloy cored wire to steel can change the morphology, quantity, size and distribution of inclusions in the steel, thereby improving the quality and performance of the steel. Using the cored wire method to add calcium metal or calcium alloy, the yield of Ca can reach 12-15%, which is 3-4 times that of the powder spraying method, and the result is much more stable, the calcium cored wire can be used this way.
3. The grain refinement of the steel
Use cored wire for steel making to add nitrogen and carbide forming elements such as vanadium, titanium, niobium to the molten steel to inhibit the deformation and recrystallization of austenite during the hot working process, prevent its grain growth, and pass their carbon and nitrogen compounds. The strain induces precipitation and precipitation strengthens the steel, thereby improving the strength and toughness of the steel; by adding a certain amount of aluminum to the steel, it forms a fine dispersive compound with the nitrogen and other elements in the steel, and get the strain-induced precipitation from the austenite crystal, thus prevents the austenite grains from growing in the subsequent hot working process; the molten steel is deoxidized, and then the rare earth ferrosilicon wire or the cerium iron wire is added to the rare earth alloy or cerium, which can purify the molten steel, control the morphology of inclusions, and generate a film that can hinder the continued growth of grains, thereby refining the steel structure. The recovery rate of vanadium, titanium, niobium, aluminum, rare earth and other elements added to steel by the cored wire method is high and stable.
4. The composition of molten steel is fine-tuned by cored wire for carbon, titanium and other elements, which can not only make their content quickly improved and obtain a high yield, but also make its fluctuation range small.
5. Microalloying of steel, adding titanium, adding boron, adding rare earth, and any other element that has a good affinity for oxygen to the steel with cored wire, can achieve much higher accuracy than the traditional furnace addition method, stability and yield.