The process of casting steel generally includes the following main steps:

Raw material preparation

Scrap steel: Select suitable scrap steel as the main raw material, with clear sources, relatively stable composition, and no excessive impurities or oil stains. Different types of scrap steel may require different process adjustments in subsequent processing to ensure the quality of the molten steel.

Ferroalloys: Prepare corresponding ferroalloys such as manganese iron, silicon iron, chromium iron, etc. according to the composition requirements of the required cast steel, to adjust the alloy element content in the steel and obtain the desired performance.

Slag making materials: Commonly used slag making materials include limestone, fluorite, etc., which are used to form slag during the smelting process, remove impurities and harmful elements from the molten steel, adjust the composition and properties of the slag, and ensure the smooth progress of the smelting process.

melting

Loading:Load prepared scrap steel and other raw materials into an electric furnace or other melting furnace in a certain order and proportion. The loading method and sequence will affect the smelting efficiency and steel quality. Generally, large pieces of scrap steel are loaded first, followed by small pieces of material and ferroalloys.

Melting: The gradual melting of raw materials inside an electric furnace using electrical or other energy sources. During the melting process, it is necessary to closely monitor the temperature and furnace conditions, adjust parameters such as power as needed, and ensure that the furnace material melts uniformly and quickly.

Refining: After the furnace charge is completely melted, it enters the refining stage. By adding refining agents, blowing oxygen or other gases into the molten steel, impurities, gases and harmful elements in the molten steel can be further removed, and the composition and temperature of the molten steel can be adjusted to improve its purity and quality.

pouring

Mold preparation: Make the corresponding mold according to the shape and size of the required casting. Casting molds can be sand molds, metal molds, etc. Sand molds have the advantages of low cost and flexible molding, while metal molds have the characteristics of high dimensional accuracy and good surface quality. Before pouring, it is necessary to dry and spray paint on the mold to improve its strength and breathability, and prevent defects in the casting.

Steel liquid adjustment: Before pouring, the temperature and composition of the steel liquid are finally adjusted and tested to ensure that the temperature of the steel liquid is appropriate and the composition meets the requirements. Excessive temperature may cause defects such as porosity and shrinkage in castings, while low temperature may lead to issues such as insufficient pouring and cold shut.

Pouring operation: Slowly and smoothly pour the adjusted molten steel into the mold, and the pouring speed and height parameters need to be reasonably controlled according to the structure and requirements of the casting. During the pouring process, attention should be paid to preventing the occurrence of splashing and curling of molten steel.

Cooling and solidification

Natural cooling: After pouring, the molten steel in the mold gradually cools and solidifies in a natural environment. The cooling rate can affect the microstructure and properties of castings. Generally speaking, when the cooling rate is fast, the grain size of castings will be relatively small, and the strength and hardness will be relatively high, but the toughness may be reduced; When the cooling rate is slow, the grains will be relatively coarse, and the strength and hardness may be lower, but the toughness is better.

Controlled cooling: For some castings with high performance requirements, it may be necessary to use controlled cooling methods, such as setting cooling water pipes around the mold, using air cooling, etc., to accurately control the cooling rate of the castings and obtain ideal microstructure and properties.

Subsequent processing

Sand removal and cleaning: After the casting has cooled to a certain temperature, sand removal is performed to remove the casting from the mold. Then clean the casting to remove surface sand particles, burrs, burrs, and burrs. Common cleaning methods include shot blasting and sandblasting.

Heat treatment: According to the performance requirements of the casting, corresponding heat treatments are carried out on the casting, such as quenching, tempering, normalizing, annealing, etc. Heat treatment can improve the microstructure of castings, enhance their strength, toughness, hardness, and other properties, eliminate casting stress, and stabilize their size and performance.

Machining: Performing necessary mechanical machining on castings, such as turning, milling, drilling, grinding, etc., to achieve the required dimensions and accuracy of the design and meet the performance requirements.

Inspection: Various inspection methods are used to inspect the quality of castings, such as visual inspection, dimensional measurement, non-destructive testing (such as ultrasonic testing, radiographic testing, magnetic particle testing, etc.), mechanical performance testing, etc., to ensure that the quality of castings meets standards and customer requirements.