3 types of cast steel and advantages and disadvantages of cast steel parts
Cast steel refers to steel used specifically for making steel castings. Cast steel should be used when the strength requirements of the casting are high and cast iron cannot meet the requirements. However, the fluidity of molten steel in cast steel is not as good as that of cast iron, so the thickness of the cast structure cannot be too small and the shape should not be too complicated. The fluidity of molten steel can be improved when the silicon content is controlled at the upper limit. 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 its variety and use.
3 types of cast steel
1. Cast carbon steel.
Cast steel with carbon as the main alloying element and a small amount of other elements. Cast low carbon steel contains less than 0.2% carbon, cast medium carbon steel contains 0.2% to 0.5% carbon, and cast high carbon steel contains more than 0.5% carbon. With the increase of carbon content, the strength and hardness of cast carbon steel increase. Cast carbon steel has high strength, plasticity and toughness, and low cost. It is used in heavy machinery to manufacture parts that bear heavy loads, such as rolling mill frames, hydraulic press bases, etc.; it is used on railway vehicles to manufacture parts that bear large forces and impacts, such as bolsters, side frames, wheels and hooks.
2. Cast low alloy steel.
Cast steel containing alloy elements such as manganese, chromium, and copper. The total amount of alloy elements is generally less than 5%, has greater impact toughness, and can obtain better mechanical properties through heat treatment. Cast low alloy steel has better performance than carbon steel, can reduce the weight of parts, and increase service life.
3. Cast special steel.
Alloy cast steel refined to meet special needs has a wide variety of varieties, usually containing one or more high amounts of alloy elements to obtain certain special properties. For example, high manganese steel containing 11% to 14% manganese can resist impact wear and is mostly used for wear-resistant parts of mining machinery and engineering machinery; various stainless steels with chromium or chromium-nickel as the main alloying elements are used for parts working under corrosive or high temperature conditions above 650°C, such as valve bodies, pumps, containers for chemical industry or turbine casings of large-capacity power stations.
Advantages of steel castings
1. Greater design flexibility
This design has more options for casting shapes and sizes, especially complex shapes and hollow parts, and steel castings can be manufactured by the unique process of core castings. Easy to form and change shape and can quickly produce finished products according to drawings can provide fast response and shorten delivery time.
2. The strongest flexibility and variability of metallurgical manufacturing
Different chemical compositions and organizational structures can be selected to meet the needs of different projects. Different heat treatment processes can select mechanical properties and use this property in a wide range and improve weldability and workability.
3. Improve overall structural strength
Due to high project reliability, coupled with weight reduction design and shorter delivery time, competitive advantages can be improved in terms of price and economy.
4. Wide range of weight variation
Small steel castings may weigh only 10 grams, while large steel castings may weigh several tons, tens or even hundreds of tons.
Compared with forged steel parts
The mechanical properties of steel castings are similar in all directions, which is superior to forged steel parts. Designers must consider the performance of materials in three directions when designing some high-tech products, which highlights the advantages of castings. Regardless of weight, volume and the amount produced at one time, steel castings can easily make complex shapes and non-stress concentration parts.
Compared with welded structures
In terms of shape and size, welded structures are more flexible than forged steel parts, but compared with steel castings, they still have the following disadvantages:
1 Easy to deform during welding.
2 It is difficult to form a streamlined structure.
3 High internal stress during welding.
4 The weld affects the appearance and reliability of the component.
Compared with iron castings and other alloy castings
Steel castings can be used in a variety of working conditions, and their mechanical properties are superior to other alloy castings.
In principle, steel castings should be used preferentially when high tensile strength or dynamic load parts are required, important pressure vessel castings, and core parts that bear heavy loads at low or high temperatures.
However, steel castings are not as good as iron castings in terms of vibration absorption, wear resistance, and mobility, and their cost is also higher than iron castings.
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