Steel casting

In the established understanding of metallurgy, custom steel part manufacturing is almost always perceived as a simple and finished technology. More about steel casting can be learned from the applicable GOST 977-88 for steel castings. In fact, these are two processes that can be separated by time and location. Manufacturing steel parts requires enormous production capacities if iron-containing ore material is used for work. As a result, such a metallurgical complex produces both finished products and steel blanks for further processing.

Steel casting can be carried out within city limits at a small enterprise. The main difference is that only scrap steel and cast iron are purchased for production. With small production capacities, steel of the required grade can be produced, and products are cast for a specific customer using such low-tonnage equipment.

Basic Concepts of Steel Casting

In a schematic view, steel casting is seen as filling a mold with molten metal. However, this is a layman’s point of view. In reality, for the finished product to acquire the operational characteristics intended by engineers, the following is required:

1. Manufacture the mold according to the available blueprint;
2. Melt the metal, removing harmful impurities (sulfur, phosphorus, etc.);
3. Add the necessary alloying elements to the melt;
4. Pour the liquid steel into molds while maintaining the correct cooling regime.

Each of these points should be considered as a separate sector in the production cycle, with its own technologies and methodologies.

Manufacturing the Casting Mold

The most advanced steel casting technologies use molds with gasifiable models. The peculiarity of this method is that the model of the cast part is made from finely fractionated gas-filled polystyrene. It is treated with an anti-stick composite, placed in a mold, and carefully filled with calibrated sand.

At the same time, the fractions of sand are changed according to the proven method. First, the finest sand grains are used, as they tightly surround the model, then the sand’s grade is increased.

All operations are performed on a vibrating table to ensure 100% filling of voids.

In the casting workshop, the molds are covered with polyethylene film, and a vacuum suction system is connected. In a vacuum atmosphere, the sand grains bond, and the casting mold gains technological density.

The polystyrene completely burns off, decomposing into a monomer, at a temperature of 320°C. The molten steel has a temperature of approximately 1500°C. Thus, the liquid metal replaces the polystyrene, forming a product that closely matches the model shape.

Metal Melting and Cleaning

For small-tonnage steel casting, an induction furnace has ideal qualities. In it, the heating and melting of metal are carried out by eddy currents. The induction furnace has the following advantages:

• The metal itself heats up in the electromagnetic field, not the furnace body;
• Heating occurs throughout the volume, which accelerates melting;
• It has the functional capability to conduct the process in a closed space, forming any gas composition above the melt under any pressure;
• There are no smoke and harmful emissions into the atmosphere.

The essence of steel manufacturing boils down to purifying iron from three elements: sulfur, phosphorus, and carbon. The carbon content, ranging from 0.02% to 2.14%, distinguishes steel from cast iron, which has a higher carbon content.

To remove harmful impurities, several methods can be applied, such as oxygen blowing or adding slag-forming components.

There is a strict dependence of the phase states of the iron-carbon alloy, which changes with temperature and chemical composition of the molten metal. Strict adherence to the technological regulation guidelines based on this pattern allows the production of steel with the desired characteristics.

Introduction of Alloying Elements

To ensure that steel has the necessary operational properties, alloying additives are added. More than 20 different elements are used for this purpose. Nickel and chromium are most commonly added, with titanium and beryllium added less frequently. For special orders, zirconium and rare-earth metals are introduced into the melt.

The properties of the final product depend not only on the percentage of each element but also on the time of addition and their relative proportions.

When marking steel, letters represent the element in the composition, and numbers denote its approximate content. If the ligand is present in an amount less than 1%, no numbers are added.

• A – Nitrogen
• D – Copper
• P – Phosphorus
• F – Vanadium
• B – Niobium
• K – Cobalt
• R – Boron
• X – Chromium
• V – Tungsten
• M – Molybdenum
• S – Silicon
• Z – Zirconium
• G – Manganese
• N – Nickel
• T – Titanium
• U – Aluminum

Pouring Steel into Molds and Cooling

This process is also quite complex since the metal poured into molds undergoes the following gradations:

• Boiling;
• Semi-calm;
• Calm.

These categories of melt are not defined by temperature but by the degree of desulfurization. If molten steel is desulfurized in the mold, when it contacts ferroalloy, the resulting gases rise and create a boiling effect. This steel is well-suited for stamping, but its structure is heterogeneous.

High-carbon steel is poured only from pre-desulfurized melts of the “calm” type.

When casting cools, the temperature regime influences the formation of the crystalline lattice of the iron-carbon alloy. Even at this stage, a sharp change in the characteristics of the finished part can occur if the cooling schedule is violated.

Precision Steel Casting to Order

High-precision steel casting involves manufacturing parts using aluminum tooling. Our factory specializes in castings weighing from 1.5 to 250 kilograms. Products are made with minimal allowances for machining.

Metal casting using precise methods involves following a strict sequence of actions and production stages. For the implementation of the technology, aluminum tooling is used, through which a model is created from polystyrene foam, precisely matching the required part. The models are then glued into clusters, painted with anti-stick paint, and placed in the mold. When molten steel is poured, the model burns off, and we obtain a casting blank. This method of casting is known as casting with gasifiable models (CGM).

Modern Steel Casting Technologies

The production of metal castings using the precise casting method has several advantages:

• The ability to produce all kinds of structures with various configurations;
• No need to use additional molds and models for casting;
• Standardized serial production;
• The ability to produce products under uniform industrial conditions.

This method allows for precise casting, which reduces costs for machining.

Steel Casting Production Targets Various Industries:

• Machine Engineering;
• Petrochemical Industry;
• Mining Industry;
• Agriculture;
• Railways.

Precise steel casting allows for significant cost savings to obtain finished products through machining.

Cooperation with the Factory

The factory performs steel casting to order. The work uses modern equipment, which eliminates the risk of defects and ensures high-quality finished products.

Steel Grades Used in Casting:

• 25L – 45L,
• 20GL,
• 20GML,
• 30HML,
• 40HL,
• 110G13L,
• CCH15-25,
• VCH 40-70.

Metal casting to order is carried out in modern workshops that meet all safety and technological standards. The standard cooperation scheme consists of the following stages:

• Agreement on the blueprint;
• Modeling of casting processes;
• Creation of a casting prototype;
• Production of an experimental batch;
• Positive conclusion received;
• Launch into serial production.

On the “KOVA FOUNDRY” website, you can familiarize yourself with examples of our casting products. The client can order the manufacture of structures – the factory specialists are ready to produce parts of any complexity based on unique drawings.