A general term for all kinds of defects that appear on the surface of precision tubes and non-ferrous metals and affect the quality of products. There are many kinds of precision tubes, most of which are named by the morphology of the defects, and others are named for their reasons.
In precision tube production, products are often divided into two categories according to the production process of defects.
One is the poor quality of steel, such as abscission layer, scarring, cracking, crack, hairline and bubble. Most of these defects are caused by poor quality of ingot.
The other is the defects of processing operation, including folding, ear, pock, convex hull, scraping, indentation, pressing into iron oxide skin, burr and so on. This kind of defect is produced in the process of plastic addition.
The inspection methods used for precision pipes of various uses are clearly stipulated in the corresponding product standards, including:
(1) the naked eye examination. For general purpose products, visual inspection of precision tubes is made by visual inspection, and sometimes by means of “test shovel” or “trial grinding”.
(2) pickling examination. A product that is suitable for important purposes.
(3) shot peening examination. For special purpose steel.
(4) nondestructive testing. In accordance with its quality requirements, J, a product of special important use, uses eddy current inspection, magnetic powder detection, penetrant flaw detection and ultrasonic flaw detection to check the precision tube (see the physical inspection of defects).
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