Definition
Cast steel refers to the steel specially used for the manufacture of steel castings. Cast steel is a kind of casting alloy, with iron and carbon as the main elements, and the carbon content is between 0-2%. Cast steel should be used when the strength requirements of castings are high and cast iron cannot meet the requirements. However, the fluidity of molten steel of cast steel is not as good as that of cast iron, so the thickness of the pouring structure should not be too small, and the shape should not be too complicated. When the silicon content is controlled to the upper limit, the fluidity of molten steel can be improved. Cast steel can be divided into general engineering cast steel, welded structure cast steel, stainless steel cast steel, and heat-resistant steel cast steel according to varieties and uses.
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Classification
Cast steel can be divided into cast alloy steel and cast carbon steel according to its chemical composition, and can also be divided into cast tool steel, cast special steel, engineering & structural casting, and cast alloy steel according to its use characteristics.
By chemical composition
- Cast carbon steel. Cast steel with carbon as the main alloying element and small amounts of other elements. Cast carbon steel can be divided into cast low carbon steel, cast medium carbon steel and cast high carbon steel. The carbon content of cast low carbon steel is less than 0.25%, the carbon content of cast medium carbon steel is between 0.25% and 0.60%, and the carbon content of cast high carbon steel is between 0.6% and 3.0%. The strength and hardness of cast carbon steel increase with the increase of carbon content.
Cast carbon steel has several advantages: lower production cost, higher strength, better toughness and stronger plasticity.
Cast carbon steel can be used to make parts that are subjected to heavy loads, such as rolling mill stands in heavy machinery, hydraulic press bases, etc. It can also be used to manufacture parts that are subjected to high forces and shocks, such as wheels, couplers, bolsters and side frames on railway vehicles.
- Cast alloy steel. Cast alloy steel can be divided into cast low alloy steel (the total amount of alloy elements is less than or equal to 5%), cast medium alloy steel (the total amount of alloy elements is between 5% and 10%) and cast high alloy steel (the total amount of alloy elements is greater than or equal to 5%). 10%).
By usage characteristics
- Cast tool steel. Cast tool steel can be divided into cast tool steel and cast die steel.
- Casting special steel. Casting special steel can be divided into cast stainless steel, cast heat-resistant steel, cast wear-resistant steel, cast nickel-based alloy, etc.
- Cast steel for engineering and structure. Cast steel for engineering and structure can be divided into cast carbon structural steel and cast alloy structural steel.
- Cast alloy steel. It can be divided into cast low alloy steel, cast medium alloy steel, and cast high alloy steel.
Features
304 and 316 cast steel are the most widely used stainless steels, both of which are austenitic cast steels, non-magnetic or weakly magnetic. And 430, 403, 410 are austenitic-ferritic stainless steels, which are magnetic.
| Classification | C | Ni | Cr | Mn | Si | S | P |
| 304 | C≤0.08 | Ni（8.00～10.00） | Cr（18.00～20.00） | Mn≤2.0 | Si≤1.0 | S≤0.030 | P≤0.035 |
| 316 | C≤0.03 | Ni（8.00～10.00） | Cr（18.00～20.00） | Mn≤2.0 | Si≤1.0 | S≤0.030 | P≤0.035 |
Advantages of Steel Castings
- Greater design flexibility
This design allows for the greatest freedom of choice in casting shape and size, especially complex shapes and hollow sections, and steel castings can be manufactured by the unique process of core castings. Easy to form and change shape and can quickly make finished products according to drawings can provide fast response and shorten lead time.
- The greatest flexibility and variability in metallurgical manufacturing
You can choose from different chemical compositions and organizational structures to suit the needs of different projects. Different heat treatment processes can select mechanical properties and use these properties over a wide range to improve solderability and workability.
- Improve overall structural strength
Due to the high project reliability, combined with the reduced weight design and short lead times, it can increase the competitive advantage in terms of price and economy.
- Wide range of weight changes
Small steel castings may only be 10 grams, while large steel castings can reach several tons, tens, or even hundreds of tons.
Compared to forged steel parts
The mechanical properties of steel castings are not much different in all directions, and they are superior to forged steel parts. Designers must consider the properties of materials in three directions when designing some high-tech products, which highlights the advantages of castings. Regardless of weight, volume, and one-time production, steel castings are easy to make complex shapes and non-stress-concentrated parts.
Compared to welded construction
In terms of shape and size, welded structures are more flexible than forged steel parts, but still have the following disadvantages compared to steel castings:
1) . It is easy to deform during welding.
2). It is difficult to form a streamlined structure.
3) . High internal stress during welding.
4) . Welds affect the appearance and reliability of parts.
Compared to iron casting and other alloy castings
Steel castings can be used in a wide variety of working conditions and have better mechanical properties than other alloy castings.
When we need high tensile strength or dynamic load components, critical pressure vessel castings, and core components that carry heavy loads at low or high temperatures, in principle, we should prefer steel castings.
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