Base metal definition

In NDT "Base Metal" only refers to the unwelded parent metal. Any metal immediately adjoining the weld would be in the Heat Affected Zone, and will likely show some signs of dilution with the weld filler metal.

The part passed because he was only testing the weld area.

The indication in the base metal is simply noted for your info.

Would that be something akin to a slag inclusion that occurred during the manufacture of the metal?

Steve

Yes, and if finding defects in the base metal is not part of the inspection criteria, it would not affect the pass/fail.

In pressure vessel and aerospace work, defects in the base metal are usually included, but in most structural work they are not.

Wow. In a pressure vessel, the defective area could be subjected to a lot of pressure, where on structural, it might be far enough away so as to not be an issue. I wonder just how many other of these were in that batch of steel, and how common these are. Probably not enough to be important, but just wondering now that we have so many cheaper and lower grade producers of steel.

Steve

Actually I have had discussions with some major steel distributors about this and they all say that steel produced today, across the board, is higher quality than ever before.

The increase in overall quality is due to the cheap and plentiful inspection technology in most mills.

It is just much easier to find discontinuities with today's technology.

"Ernie Leimkuhler" wrote

Thanks. I know that steelyard steel is up to the job for many applications, and probably far exceeds the specs. And then, when it is something supercritical, the testing will kick out anything that's not 100%. Too bad they didn't have something better when they did the Titanic. Wow. All that work, and the weak link was sulfur in the steel, IIRC.

Steve

Here's a great article that explores why Titanic sank so quickly, a very worthwhile read.

It was partly what you said, and partly the fact that the hull was riveted and not welded. Very interesting stuff, I am now reading through it.

i

Too bad they didn't have styrofoam. ;-)

Cheers! Rich

snip

Never take it for granted that the steel they shipped you was what you needed, though. At the shipyard, we have an entire code dedicated to receiving and testing all materials that will get used on the subs. Occasionally, an order will fail test, either through failing to meet chemical composition specs, or through failing heat-treat / temper /hardness tests.

For any critical application, you know what the word, "assume" breaks down to, right? "makes and ASS out of U and ME." Never assume the steelyard didn't cut some niggling little corner to save a few bucks, thereby lowering your ultimate tensile by a few percent.