Forging sampling location
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When the diameter of a disc-shaped forging is greater than 350 mm, samples are taken from a distance of 20 mm or more from the edge; why not take samples from the outer edge?
The outer edges are all excess material. . .
It is mainly to detect the internal conditions...
As mentioned above, the outer edge represents a margin of excess. Additionally, I think that during the forging process, the chemical composition and mechanical properties of the outer edge may change, making it different from the interior (it’s just my opinion; I’m not sure if it’s correct).
This post was last edited by Pinocchio on 2017-2-16 at 08:23. I think what the original poster is asking is why samples are taken from the outer edge of forgings with small diameters, while for those with larger diameters, sampling must be done at a distance of more than 20 mm from the edge. For details, refer to clause 7.3.3.2 of NB/T 47008-2010: Samples from disc-shaped forgings should be taken from the ends of these forgings; when the diameter of the disc-shaped forging is 350 mm or less, sampling is done at the outer edge, whereas when the diameter is greater than 350 mm, sampling is carried out at a distance of 20 mm or more from the edge, as shown in Figure 2c). I think it’s mainly a problem related to the heat treatment of forgings; the outer edges of large forgings cool down relatively faster, resulting in higher mechanical properties but poorer representativeness, so these areas should be avoided when taking samples. At the end face of ring forgings, a buffer ring is usually heat-treated, so sampling can be carried out directly after removing the buffer ring.
Foreign aid is a supplementary factor; what’s internal is more accurate and genuine!