The ingot casting production line is a facility that casts and solidifies molten metals (such as steel, aluminum, copper, etc.) into ingots of specific shapes and dimensions. It represents a traditional and vital production process in metalworking, particularly prevalent in the processing of large steel sections, specialty alloys, and non-ferrous metals. Compared to continuous casting processes, ingot casting lines are better suited for producing large-section, special-material, or small-batch billets. Below is a detailed introduction:
I. Types and Characteristics of Cast Ingots
Cast ingots can be categorized by material and application into several types, including:
Steel Ingots: Used for rolling large structural steel, wide plates, forgings, etc. Typically square, round, or polygonal in cross-section, weighing from several tons to hundreds of tons (e.g., large forging steel ingots can exceed 500 tons).
Non-ferrous metal ingots: Such as aluminum, copper, and magnesium ingots, available in diverse shapes (e.g., flat, round, or wire ingots). Used for rolling aluminum sheets, copper plates, aluminum profiles, etc.
Core characteristics of ingot casting: The solidification process is relatively slow, facilitating control over the internal structure of the metal; large-sized billets can be produced, but production efficiency is lower than continuous casting, and subsequent primary rolling or forging is required to open the billet.
II. Core Components and Equipment of Ingot Casting Lines
Ingot casting lines for different metals vary slightly. Taking the widely used steel ingot production line as an example, it primarily consists of the following systems:
1. Molten Steel Preparation and Conveyance System
Ladle: Holds molten steel refined and qualified from steelmaking furnaces (e.g., electric arc furnaces, open-hearth furnaces). Its capacity is determined by ingot dimensions, with refractory lining to withstand high-temperature molten steel (1500-1600°C).
Ladle Transport Car: Transfers ladles from refining stations to casting stations, ensuring stable molten steel conveyance.
2. Ingot Molds and Casting System
Ingot molds: Critical equipment for ingot forming, made of cast iron or cast steel. The internal cavity shape determines the ingot cross-section (e.g., square, round, flat molds). External cooling fins accelerate solidification. Large molds feature insulation caps (top-mounted) to minimize shrinkage cavities during solidification.
Casting Equipment: Includes ladles, pouring chutes, etc., for stable horizontal steel injection into ingot molds, preventing spatter or slag entrapment. Depending on steel grade and ingot size, either the “top-pouring method” (steel injected from the mold top) or “bottom-pouring method” (steel introduced from the mold bottom, more suitable for high-quality ingots) may be employed.
3. Mold Removal and Finishing System
Mold Removal Device: When the ingot cools to a specific temperature (typically 300-600°C), it is extracted from the mold using a crane or specialized mold removal machine (to prevent deformation or sticking due to excessive heat).
Surface Cleaning Equipment: Defects like scale, flash, and scabs are removed from the ingot surface using flame cleaning, grinding wheels, or mechanical cutting.
Hot Delivery / Slow Cooling Facilities: Some high-alloy steel ingots require slow cooling (e.g., stack cooling, pit cooling) to reduce internal stresses. Ordinary steel ingots can be hot-delivered to the primary mill for billet preparation (hot charging and delivery conserve energy).
4. Inspection and Marking System
Quality inspection equipment: Detect defects such as cracks, shrinkage cavities, and inclusions through visual inspection, ultrasonic testing, and low-magnification microstructure examination.
Marking Equipment: Prints furnace number, steel grade, weight, and other information on the ingot surface for subsequent traceability.
III. Process Flow of Ingot Production Line (Using Steel Ingots as Example)
Molten Steel Refining: After tapping from the steelmaking furnace, molten steel undergoes refining in LF furnaces, VD furnaces (vacuum degassing), etc., to adjust composition, temperature, and purity to meet ingot requirements.
Ingot Mold Preparation: The inner walls of ingot molds are coated with release agents (e.g., graphite paint), preheated to 100-200°C (to prevent cracking from rapid cooling during molten steel pouring), and arranged on the casting platform according to process requirements.
Steel Pouring: Molten steel is injected into the ingot molds via the pouring system. Pouring speed is controlled (excessive speed may cause splashing, while insufficient speed may lead to surface crusting). A heat-retaining cap is used for shrinkage compensation to minimize internal defects.
Solidification and Cooling: The molten steel gradually solidifies within the ingot mold (solidification time for large ingots can reach several hours). Solidification begins at the surface layer and progresses toward the center, forming a dense metallic structure.
Demolding and Processing: After cooling to the specified temperature, the ingot is removed from the mold. It undergoes surface cleaning and riser cutting (removing the top shrinkage cavity section) before entering the inspection phase.
Storage or Hot Delivery: Qualified ingots are stored in the warehouse or hot-delivered to the primary rolling mill/forging shop for billet preparation (rolled into billets for subsequent rolling processes).
