Cast Iron Basics: Composition, Common Grades, and Pouring Control

Cast iron is a commonly used metal material in mechanical manufacturing and industrial component production. With its good castability, relatively low cost, wear resistance, and vibration-damping properties, cast iron is widely used in mechanical manufacturing, metallurgy and mining, petrochemical industries, transportation, and other fields.

1. History of Casting

China has a long history of casting technology. Traditional casting methods mainly include clay mold (sand casting), metal mold casting, and lost-wax casting.

2. Cast Iron

Composition

The main components of cast iron are Fe, C, Si, P, and S.

• C: 2.5–4.0% 
• Si: 1.0–3.0% 

Characteristics

Cast iron has good castability, relatively simple melting and processing, and low cost. It also offers good wear resistance and vibration-damping properties.

Applications

Cast iron is widely used in mechanical manufacturing, metallurgy and mining, petrochemical industries, transportation, and other fields. Typical cast iron components include machine tool beds, engine cylinder blocks, cylinder liners, piston rings, bearing shells, and crankshafts.

3. Common Cast Iron Grades

Gray Cast Iron

HT100, HT150, HT200 are classified as common gray cast iron grades.

HT300, HT350, HT400 are classified as inoculated gray cast iron grades.

Ductile Iron

Common ductile iron grades include:

QT400-18, QT450-10, QT400-15, QT600-3, QT800-2

The last two numerical values indicate the minimum tensile strength and elongation, respectively.

Malleable Cast Iron

Common malleable cast iron grades include:

• Blackheart malleable cast iron: KTH300-06
• Pearlitic malleable cast iron: KTZ450-06
• Whiteheart malleable cast iron: KTB380-12

3.3 Common Cast Iron Grade Comparison Table

4. Casting Tolerance Grades

Casting tolerance grades are an important part of dimensional control during cast component production. 

5. Casting Roughness and Surface Finish Grades

Surface roughness and surface finish grades are also important considerations for cast components, depending on the product requirements.

6. Pouring Control Factors

Key factors in the pouring process include:

Item	Parameter
Tapping Temperature (°C)	1580–1590
Pouring Temperature (°C)	1520–1530
Molten Iron Weight (kg)	11,000
Pouring Speed (kg/sec)	~100
Pouring Ladle	15 Ton Bottom-Pouring Ladle

These parameters are the main factors specified for pouring control.

Conclusion

Cast iron is widely used in industrial component manufacturing due to its good castability, wear resistance, and vibration-damping properties.

For customized cast iron components, material grade, casting tolerances, surface quality, and pouring parameters are important factors to consider during production. Clearly defining the product drawings and technical requirements in advance can help manufacturers arrange the casting production process more accurately. However, if product drawings are not available, it’s better to ship the original samples to the manufacturer for reverse engineering, so that they can perform 3D scanning and create drawings, conduct technical analysis, supply a quotation, and arrange following production.

MATECH supports manufacturing based on your drawings or samples. Please feel free to contact us whenever you have such needs.