GB/T 9441-2009 "Metallographic Inspection of nodular cast iron" specifies the evaluation methods of spheroidizing grading, graphite size, pearlite quantity, dispersed ferrite quantity, phosphorus eutectic quantity and carbide quantity.
| Spheroidizing Fractionation | |
| Spheroidizing Level | Rate of Spheroidization |
| 1 | ≥95 |
| 2 | 90 |
| 3 | 80 |
| 4 | 70 |
| 5 | 60 |
| 6 | 50 |
Nodular cast iron is a widely used material due to its excellent mechanical properties and unique microstructure. To ensure the quality of nodular cast iron, several evaluation methods are required to be conducted on their spheroidizing grading, graphite size, pearlite quantity, dispersed ferrite quantity, phosphorus eutectic quantity, and carbide quantity. Let's take a closer look at these evaluation methods.
Spheroidizing grading:
The spheroidizing grading of nodular cast iron is an important parameter that determines the quality and performance of the material. The spheroidizing grading evaluation method is based on the shape and distribution of graphite nodules in the material. The grading is usually done according to international standards such as ISO1083, ASTM A247, and GB/T 9441.
Graphite size:
The size of graphite nodules in nodular cast iron is an important factor that affects the material's mechanical properties. The graphite size evaluation method is based on the measurement of the longest diameter of the graphite nodules. The measurement is usually done using a microscope with an image analysis system. The graphite size is also classified according to international standards such as ASTM A247 and ISO945.
Pearlite quantity:
The pearlite quantity is an important factor that affects the strength and wear resistance of nodular cast iron. The pearlite quantity evaluation method is based on the measurement of the pearlite area fraction in the material. The measurement is usually done using a microscope with an image analysis system. The pearlite quantity is also classified according to international standards such as ASTM E562.
Dispersed ferrite quantity:
The dispersed ferrite quantity is an important factor that affects the ductility and toughness of nodular cast iron. The dispersed ferrite quantity evaluation method is based on the measurement of the ferrite area fraction in the material. The measurement is usually done using a microscope with an image analysis system. The dispersed ferrite quantity is also classified according to international standards such as ASTM E562.
Phosphorus eutectic quantity:
The phosphorus eutectic quantity is an important factor that affects the mechanical properties and corrosion resistance of nodular cast iron. The phosphorus eutectic quantity evaluation method is based on the measurement of the phosphorus eutectic area fraction in the material. The measurement is usually done using a microscope with an image analysis system. The phosphorus eutectic quantity is also classified according to international standards such as ASTM A247.
Carbide quantity:
The carbide quantity is an important factor that affects the wear resistance and toughness of nodular cast iron. The carbide quantity evaluation method is based on the measurement of the carbide area fraction in the material. The measurement is usually done using a microscope with an image analysis system. The carbide quantity is also classified according to international standards such as ASTM E562.
