The main quality index of ductile iron castings is its mechanical properties, including tensile strength, elongation and hardness.
Mechanical Properties of Ductile Iron Castings
This is the main quality index for ductile iron castings. It represents the strength of ductile iron. For example, the material grade EN-GJS-500-7 (GGG50), it means the tensile strength must higher than 500 Mpa, otherwise, it will not be the qualified GGG50 grade.
The inspection method is by Multifunctional Mechanical Testing Machine. The good foundries will have this machine, otherwise, they can not guarantee their material quality.
This is another main quality index for ductile iron castings. It represents the ductility of ductile iron. If this index is smaller than requirement, it means it may be broken easier and poor ductility.
For example, the material grade EN-GJS-500-7 (GGG50), its elongation is min. 7%. Normally, the tensile strength is higher, its elongation will be lower. For example, the EN-GJS-600-3 requires the min. elongation 3%.
The elongation can also be gotten by Multifunctional Mechanical Testing Machine.
Hardness is also a important quality index for ductile iron castings. Sometimes, clients will not require the range of hardness, if so, the iron foundries could control the hardness in the normal range.
If the hardness is too low, then its material may not meet the tensile strength requirement of the required material grade. If the hardness is too high, then it may not meet the elongation requirement of the grade. Therefore, it is also an important quality index.
For the reasonable hardness range of ductile iron and gray iron, please refer to our article "Cast Iron Brinell Hardness, Ductile Iron and Gray Cast Iron" |
