What are the commonly used inspection methods for forging quality?

Forging parts must be inspected before forming and leaving factory. Inspection is divided into external quality inspection and internal quality inspection. Appearance quality inspection is generally non-destructive testing, through the naked eye or low magnifying glass can be checked, if necessary, also using non-destructive testing methods.

For the inspection of internal quality of forgings, some must adopt destructive testing, i.e. commonly referred to anatomical testing, such as low-magnification testing, fracture testing, high-magnification microstructure testing, chemical composition analysis and mechanical properties testing. Others can also adopt non-destructive testing methods. In order to evaluate the quality of forgings more accurately, the destructive testing method should be combined with the non-destructive testing method. In order to analyze the quality of forgings from a deeper level, the research of mechanism should 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. Macroscopic microstructure inspection is a kind of inspection which uses visual or low magnifying glass to observe and analyze the characteristics of forged low magnifying structure. The common methods for macroscopic inspection of forgings include low corrosion, fracture test and sulfur printing.

The so-called low-magnification corrosion method is mainly used to check the cracks, folding, shrinkage, porosity segregation, white spots, porosity, non-metallic inclusions, segregation and aggregation, streamline distribution, grain size and distribution. However, the etching and etching specifications are different for different materials to show macrostructures.

Fracture test method can be used to check the defects such as white spots, layers and internal cracks on forgings, graphite carbon of spring steel forgings, overheating and Overburning of the above-mentioned steels, and fine and uniform grain size, oxide film and oxide inclusions in aluminum, magnesium and copper alloys. Depression.

Sulfur imprinting is mainly used in large forgings of some structural steels to check whether the distribution of sulfur is uniform and how much sulfur content there is. Except for structural steel and stainless steel forgings used for low-power inspection, the forgings of other materials are generally subjected to low-power inspection after heat treatment.