Segregation of atoms in Electroslag remelted steel
Welding is widely used in many fields due to its versatility and versatility. With the advancement of welding technology, welded structures have become the main force in modern engineering. As a result, the quality of the welded structures is important for the success of engineering projects. Electroslag remelting (ESR) is one of the more commonly used welding processes and can be used to produce high quality steel welds, as well as steels raw materials. To ensure high quality ESR products, an understanding of the segregation of atoms during the ESR process is essential.
Segregation of atoms, in particular interstitial atoms, is one of the main factors influencing the properties of the ESR steel. Interstitial atoms include hydrogen, nitrogen, carbon, and oxygen. In the steady-state state, the point segregation of atoms in the steel is mainly caused by convection-diffusion. Local aberrations are caused by diffusion, suction, centrifugal force, and other factors. In ESR process, the atom segregation of steels is mainly influenced by the applied electric current, the temperature field in both the hot and cold zones, and the temperature gradient in the infiltration zone, which determines the local distribution of atoms in the welded joints.
It is difficult to accurately analyze the atom segregation of steels during the ESR process due to the complexity of the process and the difficulty of obtaining precise experimental data. Numerical modeling can provide a useful tool for helping to understand the atom segregation behavior in ESR process and allow the analysis of the relationship between the segregation and the ESR processing conditions.
The ESR process can be divided into four different stages: solidification, infiltration, remelting, and solidified. In the solidification stage, the metal pool melts due to the electric energy applied to the metal pool, while the metal flux is added as the droplet sinks to the bottom of the metal pool. This process continues until all the metal is completely molten.
In the infiltration stage, the molten metal pool liquefies, infiltrates upward into the surrounding solid metal, and then remelts the solid metal, forming an ingot at the end of the process. The temperature of the molten pool varies according to the local contact time between the electrode and the pool. A temperature gradient is formed between the top and bottom of the metal pool. Due to this temperature gradient, the point segregation of elements occurs in the infiltration zone of the ESR process.
In the remelting stage, the segregation of elements can depend on the thermodynamic characteristics of the metal. This is determined by the chemical potential of the alloying element and its diffusion coefficient, and the temperature distribution of the welding zone. The segregation of elements affects the chemical composition of the ESR steel, which further influences the properties of the steel.
In the remelted solidification stage, the segregation of elements is affected by the solidification rate and the chemical composition of the metal pool. In addition, local aberrations of the segregation can occur during the solidification process due to the edge effect, especially at the weld edges.
The atom segregation of ESR steel is very complicated due to the number of chemical components, physical conditions, and thermal gradients within the welding zone. It is important to understand the atom segregation behavior in order to obtain the desired properties in the ESR product. Numerical modeling can be used to help understand and analyze the atom segregation during ESR, and can thereby provide a valuable tool to improve the quality of ESR products.
