Common materials for ductile iron bars

2026-03-20

Ductile Iron Bar Material

Ductile Iron Bars are precision profiles in which graphite in cast iron is distributed in a spherical shape through spheroidization treatment. They combine the wear resistance and toughness of cast iron with the strength of steel, have excellent machinability, and are widely used in various fields such as machinery manufacturing and engineering construction. They have outstanding cost performance and are suitable for various complex working conditions.

1. Material Characteristics

The core material of ductile iron bars is ductile iron. By adding spheroidizing agents (such as magnesium, cerium, etc.) and inoculants, the shape of graphite is changed from flake to spherical, thereby improving the comprehensive performance of the material. The common materials and their characteristics are as follows:

QT450-10: Tensile strength ≥ 450MPa, elongation ≥ 10%, excellent toughness, good impact performance, easy cutting and processing, and moderate cost. It is the most widely used general-purpose material, suitable for making parts that bear medium loads and have certain impact requirements.
QT500-7: Tensile strength ≥ 500MPa, elongation ≥ 7%, higher strength than QT450-10, moderate toughness, and good wear resistance. It is suitable for structural parts that bear large loads and have certain requirements on strength and wear resistance.
QT600-3: Tensile strength ≥ 600MPa, elongation ≥ 3%, high strength, medium toughness, high hardness, and excellent wear resistance. It is suitable for making high-strength, low-impact force-bearing parts, such as gears and shafts.
QT700-2: Tensile strength ≥ 700MPa, elongation ≥ 2%, high strength, high hardness, and extremely excellent wear resistance, with relatively low toughness. It is suitable for heavy machinery parts that bear high loads and have extremely high wear resistance requirements.
QT900-2: Tensile strength ≥ 900MPa, elongation ≥ 2%, high strength, high hardness. After heat treatment, its wear resistance and deformation resistance can be further improved. It is suitable for core force-bearing components of high-end precision machinery and heavy-duty equipment.

All materials comply with the GB/T 1348-2019 standard, and customized material deployment can be carried out according to customer needs to meet the use requirements of different working conditions.

2. Product Specifications & Dimensions

Ductile iron bars are produced by precision casting + machining process, with high dimensional accuracy and good surface finish, which can be directly processed without complex pre-treatment. The common specifications and dimensions are as follows (unit: mm), and special specifications can be customized:

Diameter (φ)	Length (L)	Tolerance Range (Diameter)	Surface Finish	Applicable Material	Remarks
20-50	1000-6000	±0.05	Ra≤1.6μm	QT450-10, QT500-7	Small diameter, suitable for precision small parts
51-100	1000-6000	±0.08	Ra≤1.6μm	QT450-10, QT500-7, QT600-3	General diameter, most widely used
101-200	1000-4000	±0.10	Ra≤3.2μm	QT500-7, QT600-3, QT700-2	Medium diameter, suitable for medium load parts
201-300	1000-3000	±0.12	Ra≤3.2μm	QT600-3, QT700-2, QT900-2	Large diameter, suitable for heavy machinery parts
301-500	1000-2000	±0.15	Ra≤6.3μm	QT700-2, QT900-2	Extra large diameter, customized production

Customization Range: Diameter φ20-φ500mm, length 1000-6000mm (splicing available for extra length), tolerance can be adjusted to ±0.03mm according to requirements, and the surface can be polished and rust-proof treated.

3. Product Applications

With its excellent comprehensive performance, ductile iron bars are widely used in various industries such as machinery manufacturing, engineering construction, automobile industry, metallurgy and mining. The specific applications are as follows:

1. Machinery Manufacturing Industry (Core Application)

It is mainly used to make various mechanical parts, such as gears, shafts, sleeves, cams, connecting rods, crankshafts, etc. With its good wear resistance and toughness, it can replace some steel, reduce production costs, and ensure the service life and operation stability of parts. For example, QT600-3 material can be used to make machine tool gears and reducer shafts, and QT700-2 material can be used to make eccentric shafts and crankshafts of heavy machinery.

2. Automobile Industry

It is suitable for the production of automobile chassis, engine, gearbox and other components, such as automobile steering knuckles, differential housings, gearbox gears, engine brackets, etc. The high strength and impact resistance of ductile iron bars can meet the complex force requirements during automobile driving, and its lightweight characteristics help reduce automobile fuel consumption.

3. Engineering Construction and Municipal Field

It is used to make manhole covers, manhole seats, pipe joints, valve housings, etc. in municipal engineering, as well as scaffolding accessories, tower crane accessories, bridge connectors, etc. in construction engineering. The QT450-10 ductile iron bar has good toughness and impact resistance, which can effectively avoid municipal facilities from being damaged by external impact, and its service life can reach several decades.

4. Metallurgy and Mining Industry

It is suitable for wear-resistant components of metallurgical equipment and mining machinery, such as crusher liners, conveyor rollers, mining drill bits, metallurgical furnace accessories, etc. The QT900-2 ductile iron bar has high hardness and extremely strong wear resistance, which can bear high loads and high wear under mining and metallurgical working conditions, and reduce equipment maintenance costs.