Re-inspection of material metallography
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According to requirement 6.3.9.1 in HG20581, steel pipes with a design pressure of ≥10 MPa shall undergo metallographic testing; the material used is 16Mn. What are the specific testing items?
In my understanding, it refers to the inspection of chemical components, such as the carbon content and phosphorus content; the regulations in GB6479 can be referred to for this purpose
The metallographic inspection of steel pipes, taking GB6479 as an example, mainly refers to the inspection of the microstructure at low magnification and the inspection for non-metallic inclusions.
It seems to be about checking the metallographic structure, grain size, inclusions, and things like that; GB6479 covers this, but I haven’t seen it. By the way, it appears that the section on metallographic testing is no longer included in Chapter 6.3 of HG/T20581-2011
:) You can take a look at the relevant standards, such as pressure vessel standards, and so on
Metallography mainly deals with things like non-metallic inclusions and grain size.