Charles McDonald

Cracks in Mild Steel

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Hello there,

The other day I was forging a bottle opener and a hook and after pulling them out of the pickle I use to clean off scale I noticed a small crack that ran along the length of them. I wondered the reasoning for it (perhaps it was my doing) and then I looked at the 3/8x3/4 flat bar I cut out of and noticed the crack ran all the way though it as well. I threw in my scrap bin, but yesterday I used some 1/8x1/2 flat bar and it has the same thing along the edges. I should mention that these cracks dont go all the way through but are only on one side. What could be causing this?

Thanks ahead,

Jake

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Just a real wild guess here is they were not made in america!
I woiuld also guess the using some flux and forge welding them as youi work into the shape you wish might work. If yoiu are not into forge welding this may be a good place to spend some time at it. There is a lot of info on this site abouit that in the foumrs and in the bps. Found by looking on home page and clicking pages, and then bps,,

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A36 is a crap shoot, or maybe a bit more ''like a box of chocolates'' as F Gump would say......Don't ever quench it red hot, esp if you plan on cold twisting or bending........ ;) .........Better yet, just let it cool..... B)

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Rich: Ive accomplished a couple of forge welds, but havent worked on getting it down enough, and I need to! Its fun :)

Macbruce: Ah so its just a matter of low quality I suppose, I thought maybe something else might be a factor. Im a bit irritated that I got two pieces this way. This tells me that might be a more common thing from the place I buy it...

Thank you both!

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I don't think its anything you did wrong in forging. If it was from forging I don't think it would follow the contour of the piece so perfectly. A lot of the hot roll flat bar I use comes with cracks like that. Or they come twisted, out of square/round etc. I get it cheap so I just deal with it.

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You sure that's not a fold? Sometimes you don't see them when the steel is red.

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It couldnt be a fold because its on the unused stock as well.

Its not a big deal, ill just work around it when I find it, my curiousity just had me on this one and so I thought Id ask :)

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Good info on this subject here:
http://blacksmith.org/forums/threads/2183-Steel-Designation-Myth-vs-Fact?p=16097#post16097
Follow the links there for more info
smith out

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That is a fold in the parent material. It is from the rolling mill process. There is little you can do to get rid of it. The fold is filled with scale and very hard to weld.

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I worked in the manufacturing of large (and small) power transmission and traffic lighting and control standards for many years. Most of our product was made from A36 and other forms of mild steel. There was sometimes lamination in plate as well as sheet steel. I was told it happened in the production of the steel at the mill. Impurities (most of todays steel contains a lot of scrap) gets trapped in the mix and when the steel is rolled out to its prescribed thickness, these impurities manifest themselves as a crack or even a separation along the grain of the sheet or plate. I have seen 2" plate appear to be two pieces of 1" plate sandwiched together. No, its not normal; We would have to scrap the material and sometime finished product when it was found. Usually turned up when a piece was bent in a brake press or discovered in routine ultra-sound or magnaflux testing. Sometimes it just showed up after welding a base plate to a pole shaft. The lamination would separate due to the heat stress.

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What Dodge said.

The steel we get these days is the junk they put together with all the scrap metals you see hauled out on rail cars and such. Whether the steel is marked Taiwan, China, Japan, Canada...doesn't matter. Cars, appliances, a mish mash of different alloys. I remember one day in the shop where my guys ran through three band saw blades on one cut before I could put a hault to the idiots. Why they kept trying to cut in the same spot I don't know but one of those guys wasn't employed for much longer. We chalked it up to a ball bearing in the bar, cut around it and moved on. Wasn't the first or last time we ran into that. Plate steel is the same way, maybe even worse.

Today's steel (1018, 1045, A36, etc) doesn't hold a candle to that of 30 years ago.

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Well I'd argue that on the specifically spec'd stuff as it has to meet the spec. However most folks are not willing to *pay* for the higher grade stuff and settle for alloys with a much looser spec---like A36 with it's yield strength spec rather than a tight elemental spec.

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My best guess would lean toward saying your issue isn't necessarily a crack but a delamination of the base material. Maybe you got a bad batch of flat/bar stock. Cheap Chinese-made steel will tend to delaminate. Its caused by a bad cold-rolling at the mill: it rolls the metal over itself and presses it together to where the naked eye can't see it through the mill scale..... Only other alternative explanation is you are forging to cold or its not mild steel.

-Hillbilly

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