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zh 3 minutes to figure out pig iron and cast iron（iron casting））
2025-02-10 09:15:26 hits：0
What's the Difference Between Pig Iron and Cast Iron? Understand the Composition, Performance, and Application Fields in 3 Minutes
In the vast world of metal materials, pig iron and cast iron are often confusing, yet each has its unique value. This article will deeply analyze their differences, from chemical composition to physical properties, and then to practical application fields, helping you easily master them in 3 minutes.
I. Core Differences between Pig Iron and Cast Iron
1. Carbon Content Differences
The carbon content of pig iron is ≥2.1%, usually in the range of 2.5% - 4.5%. It is directly produced from blast furnace smelting. At high temperatures, raw materials such as iron ore, coke, and limestone undergo a series of complex reactions, and the produced pig iron contains more impurities. While the carbon content of cast iron is between 2.1% - 4%. It is carefully made by remelting pig iron and adding elements such as silicon and manganese, and the composition is more controllable. This slight difference in carbon content largely determines their subsequent performance trends.
2. Production Process Comparison
Pig iron production relies on the reduction of iron ore in a blast furnace. The iron ore is reduced at high temperatures in the blast furnace, and finally, liquid pig iron is produced, which is then directly cast into ingots, that is, what we often call pig iron ingots. The production of cast iron is to remelt the pig iron ingots, precisely adjust the composition during this process, and then cast them into shapes. According to different requirements, gray cast iron, ductile cast iron, etc. are made. Blast furnace pig iron is the source of the entire iron and steel industry chain, and the ductile cast iron process has opened a new door for the high - performance application of cast iron.
3. Physical Property Characteristics
Pig iron has high hardness but extremely high brittleness, which makes it ineffective when facing machining. It is more often used as a raw material for heavy industry. After a series of process adjustments, cast iron has significantly improved ductility and compressive resistance, and its performance can be further improved through heat treatment. It is very suitable for the precision casting field and can manufacture various complex and precise parts.
II. Application Fields and Market Value of Pig Iron
1. Core Raw Material for Steel - making
Globally, up to 90% of pig iron is used for converter steel - making. In the steel - making process, through the decarburization process, pig iron is gradually transformed into various steels with different properties. Blast furnace pig iron, as the "starting raw material" of the iron and steel industry chain, its quality directly affects the quality of subsequent steel products. It can be said that without high - quality blast furnace pig iron, it is difficult to produce high - performance steel.
2. Basic Material for the Casting Industry
Foundry pig iron is an indispensable basic material for the casting industry. Its characteristics of low cost and good fluidity make it show great advantages when manufacturing large - scale castings such as machine tool bases and engine blocks. It can easily fill complex molds and provide a solid guarantee for the manufacturing of large - scale mechanical equipment.
3. Special Types of Pig Iron
Spiegeleisen, this kind of pig iron containing manganese, is mainly used for the manufacturing of wear - resistant parts and plays an important role in some industrial scenarios with extremely high requirements for wear resistance. Ferrosilicon is often used as a deoxidizer and alloy additive in steel - making, effectively improving the quality and performance of steel.
III. Main Types and Practical Applications of Cast Iron
1. Gray Cast Iron
The graphite in gray cast iron is in flake form, which endows it with good shock absorption and low cost. It can be seen in fields such as automobile engine blocks, machine tool guides, and municipal manhole covers, silently contributing to our lives and industrial production.
2. Ductile Cast Iron
The graphite in ductile cast iron is in spherical form, its strength is close to that of steel, and its corrosion resistance is also very strong. Scenarios with high requirements for strength and corrosion resistance, such as water transmission pipelines, gearboxes, and the bases of wind turbine generator sets, are exactly the arenas where ductile cast iron can show its prowess.
3. Malleable Cast Iron
Malleable cast iron has its toughness improved through annealing treatment and can withstand impact loads. In products such as railway accessories, hardware tools, and building fasteners, malleable cast iron ensures the safe use of these products with its unique performance.
IV. How to Choose Pig Iron or Cast Iron? 3 Key Decision - making Points
1. According to Product Performance Requirements
If the product requires a high - hardness raw material, then pig iron is undoubtedly the first choice; but if the product needs to be processed into complex shapes, cast iron is more competent.
2. Cost and Process Considerations
The unit price of pig iron is relatively low, but using it requires supporting steel - making or casting equipment; cast iron is flexible in processing and more suitable for the production of small and medium - sized parts. Enterprises can choose according to their own production scale and equipment conditions.
3. Industry Standard Requirements
In the automotive manufacturing industry, due to the strict requirements for part performance, ductile cast iron is preferentially used; while in the manufacturing of building basic parts, gray cast iron becomes a better choice because of its high cost - performance ratio.
V. Frequently Asked Questions about Pig Iron and Cast Iron
Q: Can pig iron be directly processed into parts?
A: It is not recommended. Pig iron is very brittle and is extremely likely to break during the processing. Usually, it needs to be first made into steel or remelted into cast iron before processing.
Q: Is ductile cast iron more durable than steel?
A: Ductile cast iron is superior to ordinary steel in terms of corrosion resistance and shock absorption, but in terms of strength, it is still lower than alloy steel. The specific durability needs to be judged according to the actual use scenario.
Q: Why does pig iron need special packaging for export?
A: Pig iron ingots are easy to oxidize. To ensure their quality, vacuum moisture - proof packaging is required, and a composition report also needs to be marked so that the importer can understand the product details.
Conclusion
The differences between pig iron and cast iron ultimately stem from the differences in composition and process, and these differences directly determine their application scenarios. As an international pig iron supplier, Tiegu, with professional technology and rich experience, provides high - purity foundry pig iron and customized solutions, covering a wide range of fields such as steel - making, automobile manufacturing, and heavy machinery. If you need to obtain pig iron composition test reports or cast iron technical parameters, please feel free to contact our foreign trade team at any time. We will serve you wholeheartedly.
