EN-GJL-250 is a grade of grey cast iron, according to EN 1561-2011 standard
Chemical composition
– Carbon (C): 3.16-3.30
– Silicon (Si): 1.79-1.93
– Manganese (Mn): 0.89-1.04
– Sulfur (S): 0.094-0.125
– Phosphorus (P): 0.120-0.170
Mechanical properties
– Tensile strength (Rm): 250 MPa
– Hardness (RH=1): 209 HB
– Sample size: Rod diameter: 30 mm
Other characteristics
– Good strength, wear resistance and heat resistance
– Excellent vibration damping performance
– Excellent casting performance, artificial aging treatment is required
– Application range: suitable for pump casings, containers, towers, flanges, stuffing boxes and covers, carbide towers, nitrification towers, etc. It is also used for processing beds, columns, cylinders, gears and parts that require surface quenching.
– Due to small thermal deformation, it is often used in high temperature environments.
Specifications and organization
– Heat treatment specifications: (specified by the supplier, details provided for reference)
– Organization: flake graphite + pearlite
EN-GJL-250 quenching can reach HRC60, but gray cast iron is generally annealed or normalized without quenching. If hardness is required in a specific area, high-frequency or medium-frequency quenching can be performed.
– Medium-frequency quenching: quenching depth 3-5mm, hardness HRC50, and minimal deformation of the workpiece.
– High-frequency quenching: quenching depth 1-2mm, quenching temperature 850℃, surface hardness above HRC50; quenching temperature 900-1000℃, surface hardness up to HRC60.
Heat treatment specifications
The heat treatment specifications of EN-GJL-250 are generally determined by the supplier. EN-GJL-250 is generally used in the cast or normalized state without quenching. If local hardness is required, high-frequency or medium-frequency quenching can be used:
Medium-frequency quenching: hardened layer 3~5mm, hardness up to HRC50, small deformation of the workpiece.
High-frequency quenching: hardened layer 1~2mm, quenching temperature 850 can make the surface hardness reach HRC50 or above; quenching temperature 900~1000 degrees can make the surface hardness reach HRC60.
Application
EN-GJL-250 is used to manufacture pump casings, containers, towers, flanges, stuffing boxes and glands, carbonizing towers, nitrifying towers, etc. It is also used to manufacture machine tool beds, columns, cylinders, gears and parts that require surface quenching. Because of its small thermal deformation, it is often used in high temperature environments.
International standard equivalents
In the United States, the standard for gray cast iron is ASTM A48/A48M. The US equivalent of HT250 grey cast iron is Grade 220 or Grade 260. These standards focus on the minimum tensile strength and yield strength of the material and specify the chemical composition and heat treatment process.
In Japan, the standard for grey cast iron is JIS FC 250. This standard is similar to EN-GJL-250 in terms of chemical composition and mechanical properties, but the specific values and requirements may vary to suit the Japanese domestic market and engineering practices.
The international counterpart of grey cast iron in the ISO standard is ISO 185. This standard specifies the classification, requirements and test methods of grey cast iron, and aims to provide uniform technical specifications for the production and application of grey cast iron worldwide. The performance indicators of EN-GJL-250 grey cast iron match some grades in ISO 185.
