What do the markings on this steel plate tell me?

[JimGnitecki]

As Mcgyver said HT is the heat number used to trace the composition of the steel. When I was working I had to order material for QA jobs and the HT # was required for tracing. We also required a copy of the mill certificate for our records. These numbers would then be written or stamped on all the material used for the job. It was used mostly on pipe. The info was recorded in a data base, along with date, QA number and PO #

That makes sense. In high quality or closely regulated processes, this would be important in the event something later went wrong with the item(s) made with that material batch.

Many years ago I had a friend who ran a Honeywell diagnostic laboratory that investigated a U.S. military jet's unexplained control surface failure in flight and subsequent crash. His team analyzed parts from the aircraft looking for fabrication or process anomalies. They found one. A piece with deviant metallurgy was identified, and was traced back to a specific heat treatment which was confirmed to have been done incorrectly.

Jim G

 

[Susquatch]

A piece with deviant metallurgy was identified, and was traced back to a specific heat treatment which was confirmed to have been done incorrectly.

The auto industry does this too. Especially for safety related parts. Many a recall has been based on tracing a problem back to a batch of bad metallurgy.

The fundamental issue is the drive to reduce weight. Which dictates parts that are tightly designed for the application. As a result bad metallurgy results in failed parts. To limit the scope of recalls like this, metallurgy is tracked by date and batch.

 

[trevj]

No its a cut off, look at the start of cut, if it was an order the start would not be in it.

Ayup. Just a big enough piece that someone might see fit to put it to a use where they actually care about batch numbers and the like. Good habit to be in, marking the off cuts, with the same numbers as the original plate or bar carried.

 

[Former Member]

Ayup. Just a big enough piece that someone might see fit to put it to a use where they actually care about batch numbers and the like. Good habit to be in, marking the off cuts, with the same numbers as the original plate or bar carried.

Something I should do with my cut offs, though its all 6061 so maybe not

 

[JimGnitecki]

Ayup. Just a big enough piece that someone might see fit to put it to a use where they actually care about batch numbers and the like. Good habit to be in, marking the off cuts, with the same numbers as the original plate or bar carried.

So, indication of a well run shop?

Jim G

 

[Downwindtracker2]

I worked in a wire mill which specialized in custom high carbon orders. The same grade of steel could be all over the map in quality. Different steel mills. When we made wire for the wire rope in arresting cables, it was brand, grade, and then only certain heat #s.

 

[trevj]

So, indication of a well run shop?

Jim G

I would think so!

If only from the perspective, that they would know what they were selling to the customer!

I used to tell the apprentices in our shop, that if they cut the markings off the bar in the rack (instead of cutting the other end), that I would use their forehead to drive the punches to re-mark the bar.

Because a bar that has no identification on it, is just so much scrap metal!

 

[Rauce]

About a year and a half ago at my old job we cleaned out the racks. Some unmarked steel and aluminum material was kept and seperated because it can be handy for non-customer stuff like fixtures and whatnot. We scrapped all the unmarked brass and bronze though and it was almost exactly a ton of material. Something like $7k I think. Usually scrap run money went into a kitty for bbqs and stuff but not that time haha.