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Methods for Foundries to Inspect Ductile Iron Castings


With the demand for Ductile Iron Castings ever rising, foundries have cropped up by the dozens to cater to this need. It becomes very important then to ensure that the Ductile Iron, that one is purchasing, is of the best quality. Even the foundries themselves keep inspecting their products, to ensure their survival in the market.

Following are the Inspection Methods for Ductile Iron Castings:

Metallographic Inspection: In this method, the samples of the Ductile Iron material are taken and scrutinized under the microscope. The structure and nature of the graphite in the Ductile Iron material are then analyzed. The graphite in Ductile Iron Castings has nodular or spherical shapes which bring out the full potential of the matrix. The nodularity is taken as a measurement of the quality of the material.

Chemical Analysis: Chemical analysis is used to ascertain the content of chemicals. Specialized chemical analysis instruments like DF100 Direct Reading Spectrometer are used for the purposes.

Tests based on the Mechanical Properties: Ductile Iron is the hardest and has the highest Tensile strength among the Iron alloys. Thus, tests which evaluate these Mechanical Properties are done to ascertain the quality of the Ductile Iron Castings. Since the Tensile Test is not feasible every time, the hardness test is preferred most of the times. Usually, a force of 3000kg and a pressure ball of 10mm diameter are considered as ideal for a proper test.

Surface Inspection: There are 3 methods of Surface Inspection:
(a) Ductile Iron when cut produces chips and strips. On the other hand, Grey Iron tends to be powdery in nature
(b) The sound which a body made of Ductile Iron makes when hit, is pleasant and creates sound waves in harmonic motion. The sound which a body made of Grey Iron will make on the other hand is more like a thud
(c) The surface of the Ductile Iron can be checked for any defects like cracks, air holes, slag inclusion etc.

Magnetic Particle Inspection: Ductile Iron Castings can also be subjected to Magnetic Particle Inspection to check for any defects, especially in the casting head areas.

Ultrasonic Testing: Ultrasonic Testing can not only reveal any dents or holes on the surface of the Ductile Iron but also show cracks and other defects on the inside of the material. However, care has to be taken while analyzing the results of the Ultrasonic Tests. The complex structure of the Ductile Iron Casting raises the possibility of wrong judgments.

Foundries put the Ductile Iron Casting through the above mentioned Inspection Methods to make sure that the material which leave the foundries are of high quality.




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Add: No.1-4-6, Jianshe Road, Qianyang, Donggang City, Dandong, Liaoning, China 
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