What are the common inspection methods for forging quality?

Forging parts should be inspected before they are manufactured and manufactured. The inspections are divided into external quality inspection and internal quality inspection. Generally speaking, the inspection of appearance quality belongs to non-destructive inspection, which can be carried out by naked eyes or low magnifying glasses, and non-destructive inspection is also used when necessary.

For the internal quality inspection of forgings, some must adopt destructive inspection because of the requirements of its inspection contents, that is, the commonly described anatomical test, such as low magnification test, fracture test, high magnification structure test, chemical composition analysis and mechanical properties test, and some can also adopt non-destructive testing method. In order to evaluate the quality of forgings more accurately, destructive testing should be adopted. The test method and non-destructive testing method are combined for use. In order to analyze the quality problems of forgings at a deeper level, the study of mechanism should also be done by means of transmission or scanning electron microscopy, electron probe and so on.

At present, the commonly used inspection methods for internal quality of forgings are macro-structure inspection, micro-structure inspection, mechanical properties inspection, chemical composition analysis and non-destructive testing. Among them, macro-structure inspection is a kind of inspection to observe and analyze the characteristics of low-magnification structure of forging by using visual or low-magnification magnifying glass. The commonly used methods for macro-structure inspection of forgings are low-magnification corrosion method, fracture test method and sulfur imprint method.

The so-called low-magnification corrosion method is mainly used to check the crack, folding, shrinkage, pore segregation, white spot, loose, non-metallic inclusions, segregation concentration, streamline distribution, grain size and distribution of forgings. It is only for different materials that the etchant and the etching criterion are different when the macrostructure is displayed. -

There are also fracture test methods, which can be used to check the possible defects such as white spots, layers, internal cracks on forgings, graphite carbon of spring steel forgings and the overheating and overheating of the above-mentioned steels, etc. For aluminum, magnesium, copper and other alloys, it can be used to check whether the grains are fine and uniform, whether there are oxide films, oxide inclusions and other defects.

The sulphur printing method is mainly used in some large forgings of structural steels to check whether the distribution of sulphur is uniform and the content of sulphur. Except for structural steel and stainless steel forgings which are used for low magnification inspection, the forgings of other materials are generally checked after final heat treatment.

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