Steel casting: a key stage in metallurgical production

Steel casting is a process in which molten metal from a ladle is poured into molds or molds to produce ingots. This stage of metallurgical production is crucial, since the final condition and characteristics of the final product directly depend on its quality.

The main parameters of steel casting

Pouring speed

The optimal casting speed ensures that the forms are filled evenly, preventing the formation of defects. If the process goes too fast, it can cause cracks and porosity. Excessively slow pouring can lead to the formation of shrinkage shells.

Steel temperature

In order for steel to have good fluidity and fully fill the mold, its temperature must be between about 1500—1600 °C. Overheating steel contributes to the oxidation of the metal and can lead to defects.

Oxidation protection

During the casting process, it is extremely important to protect steel from interaction with oxygen in the air to avoid the formation of oxides. For this purpose, protective gases or special fireproof coatings are used that minimize the contact of steel with air.

Casting defects and their impact on the final product

If the technological requirements of casting are not met, defects may occur in the finished metal that significantly impair its quality. The most common ones include:

• Cracks — are formed due to uneven cooling of steel or a high content of harmful impurities. Cracks degrade the quality of ingots and prevent them from further forging.
• Porosity — appears due to insufficient filling of forms or due to rapid cooling of steel. This defect significantly reduces the strength of the material.
• Shrinkage sinks — occur as a result of metal shrinkage during cooling. The presence of such defects requires the removal of a significant part of the finished product, reducing the overall yield of usable metal.

Types of steel castings

Casting into molds

Casting steel into molds is one of the traditional methods in which liquid metal is poured into special cast iron molds (molds). Molds can be of various sizes and configurations, depending on the required properties and ingot parameters.

Features of casting into molds:

1. Preparation of molds. Before casting, the molds are thoroughly cleaned and heated to a certain temperature, which prevents the formation of defects on the ingot surface.
2. Cooling. Molds with liquid metal are cooled both naturally and forcibly. Forced cooling accelerates the hardening process and improves the steel structure.
3. Ingot extraction. After complete cooling, the ingots are removed from the molds and further processed, in particular, trimming, peeling and heat treatment.

The advantages of casting steel into molds include the possibility of producing ingots of various sizes and shapes, as well as the relatively low cost of equipment. However, this method of casting requires more time and effort than other methods, such as continuous casting. In addition, casting into molds may cause some defects, such as cracks, porosity and shrinkage.

Casting into molds can be done in two main ways:

• pouring from above;
• siphon casting.

Pouring from above

In this method, liquid steel is poured directly into the upper part of the mold. This method makes it possible to obtain ingots with a cleaner surface, since when falling and hitting the bottom of the mold, the metal jet is released from non-metallic inclusions.

This casting method is used on PZPS for the production of high-quality precision alloys, such as:

• 49K2FA-VI, 27KH, 50N, 50NP, 79NM, 80NM, 81NMA — magnetically soft materials;
• EP-298, 13NHM — magnetic-hard alloys;
• 40KHNM, 36NHTYU, 17HNGT — materials with specified elastic properties;
• X15YU5, X23U5, X23YU5T, X20N80N, X15N60N — alloys with high electrical resistance;
• 29NK, 36N, 42N — alloys with a given temperature coefficient of linear expansion.

In addition, this makes it possible to obtain other high-quality materials:

• corrosion-resistant steels 12X18H10T, 12X18N9, 12X18N9SMR, 10X17N13M3T;
• heat-resistant and heat-resistant alloys HN78T, 20X13.

The materials presented above are widely in demand in various industries due to their unique physical and mechanical properties and compliance with modern quality standards.

Siphon casting

During siphon casting, liquid steel flows from the bucket into the molds from below through a system of channels, which makes it possible to simultaneously fill several forms. Due to the simultaneous filling of several molds, the productivity of the process increases significantly.

Features of siphon casting:

1. Preparing the system. Before pouring, it is necessary to carefully prepare the system of channels and molds to prevent leaks and other problems.
2. Pouring steel. Steel is poured into the channel system at a certain speed and under a certain pressure. This is also important to prevent the formation of traffic jams and other defects.
3. Cooling. After filling, the channel system and molds are cooled naturally or forcibly.
4. Extraction of ingots. After complete cooling, the ingots are removed from the molds. They are then further processed.

Among the advantages of the siphon method, it is worth highlighting the ability to simultaneously fill several molds and the high productivity of the technological process. However, this method of casting requires complex preparation and careful control, and also has a higher cost due to the cost of the equipment used and the labor costs to maintain its performance.

Continuous casting

During continuous casting, liquid metal is poured into a crystallizer — a water-cooled mold without a bottom, where primary solidification takes place. Then the workpiece, the core of which remains liquid, is pulled out of the crystallizer and enters the secondary cooling zone, where it finally solidifies. After that, the workpiece is cut into measured lengths and sent for further processing. Before starting casting, a temporary bottom, called a seed, is set in the crystallizer.

Continuous casting has several advantages over moulding:

• High performance. This method of casting steel makes it possible to automate the process and obtain longer workpieces at high speed, which is especially important for mass production.
• Low production costs. Reducing time and labor costs, reducing material and energy consumption make this method cost-effective for mass production.
• High product quality. The uniform distribution of chemical elements (reduction of chemical heterogeneity) and mechanical properties across the workpiece section ensures high product quality.

However, continuous casting also has some disadvantages:

• The complexity of the equipment. Continuous filling requires complex and expensive equipment that requires careful maintenance and control.
• Restrictions on the size and shape of workpieces. The blanks obtained by continuous casting have limited dimensions and shapes, which is a disadvantage for some types of products.

This method of casting is best suited for the production of ordinary steels in the form of blanks having standard dimensions and shapes.

Production of high-quality steels at PZPS

The St. Petersburg Precision Alloy Plant specializes in the production of high-quality steels and alloys, and also provides a number of production services. The plant has a modern production base and qualified personnel, and also strictly monitors the compliance of its products with current standards, which guarantees the stable quality of its materials.

The plant's products include alloys with unique magnetic, elastic and corrosion-resistant properties, which makes PZPS a reliable partner for enterprises in various industries. For cooperation questions, please contact the following phones or leave application. Our specialists will call you back and answer your questions in detail.

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