Garbage Steel

[carrdo]

HI All,

This is what we are dealing with these days.

There is over 1/4" of warpage at the free ends of these two hot rolled steel strips which are 8" long x 3/16" thick x 1/2" wide nominal. This is after rough and finish machining both sides of the strip (to 5/32" finished thickness). It is not due to the machining process either as the finished thickness "mike's" not more than 0.001" difference at each end. And hot rolled steel is supposed to warp less than long thin pieces of machined cold rolled steel!!.

The 12' long strip bar stock itself was recently purchased at a well known local and North American metal supplier.

Thank goodness it doesn't say made in Canada as it has to if produced here in this country.

 

[Tom O]

It look fairly parallel for the fist few inches before it goes mad could it be the metal is bent slightly?

 

[Tom Kitta]

Strips are bent.

If you want to see garbage metal get stuff from Ukraine. Garbage is defined as a metal with a lot of inclusions and inconsistent chemistry.

 

[MashingMetal]

That explains all the short pieces listed for sale on Aliexpress
I bought one of those dump trailers for my lawn tractor a few years ago and this summer I stripped and painted it. I could not believe how pitted the Chinese steel was, pure crap.

 

[carrdo]

Hi All,

I can't see how it would be bent as the thickness mike's the same all along the length of each strip and even if I machined out the bend, it wouldn't show as a bell mouth as it does . This is typical internal stress redistribution starting from perhaps a too rapid cooling of the metal. I have seen this before but not to this degree.

 

[1018Machine]

Can't speak from experience on carbon steel but I can regarding buying off shore aluminum alloys! It's fine for working with but don't try to anodize it, all kinds of problems occur. Once I learned that I only buy Kaiser!

 

[Megar arc 5040dd]

HI All,

This is what we are dealing with these days.

There is over 1/4" of warpage at the free ends of these two hot rolled steel strips which are 8" long x 3/16" thick x 1/2" wide nominal. This is after rough and finish machining both sides of the strip (to 5/32" finished thickness). It is not due to the machining process either as the finished thickness "mike's" not more than 0.001" difference at each end. And hot rolled steel is supposed to warp less than long thin pieces of machined cold rolled steel!!.

The 12' long strip bar stock itself was recently purchased at a well known local and North American metal supplier.

Thank goodness it doesn't say made in Canada as it has to if produced here in this country.

Less stress is doesn't mean no stress. This can happen even with hot rolled. Also it could be slightly bent and still mic the same sown its length. You can have two parallel surfaces that are curved so the thickness does not need to be different in a gradual bend.

 

[carrdo]

Hi All,

Yes, I know that HR steel will have some residual internal stress but not that of CR steel. And no, the bars were not bent as the photo shown of these bars was after rough milling and then finish grinding both sides of the bars dead flat on a surface grinder.

I also had an observation (on another machinist website) that the parent strip could have been rolled at too low a temperature which would induce high surface stresses somewhat similar to CR steel.

 

[Downwindtracker2]

I was told and warned that CRS has more internal stress than HRS. The last CRS I bought, I found it to be out of round and undersized. Steel will vary batch to batch, that is why when they work with it, they track heat #s.