Cracks developing during a twist

[Neil Blythin]

I've *never* had a problem with this before, and am a bit stumped as to what's happening...

I made a couple of handles yesterday out if 3/8" square hot rolled mild steel. Just finished wire brushing them (after a vinegar bath to remove scale), and noticed cracks along the edges of the twist.

I twist well into the oranges (and understand this stuff can be twisted cold), so I can't imagine that was an issue.

Again, I've never run into this with mild steel before. Any thoughts?

Alright, here we go with some photos.

[ThomasPowers]

Is it mild steel or is it A36?  I have some sticks of A36 do that and others not. I attributed it to the nature of the beast.

[John McPherson]

As Thomas noted, A36 is prone to all sorts of ailments due to the inconsistent nature of the melts.  The imported stuff is dreck. It is the 69 cent/pound hamburger (the other white meat  :blink:  ) of the steel world. Your batch may be high in copper, lead, sulfur, etc.

 

If you need quality, you have to specify the grade you want, such as 1018. Demand certs with each batch.

[Neil Blythin]

Thanks guys. I suspect you're right.  I've been getting my steel from Metal Supermarkets, had run out of 3/8" and just restocked. I'm guessing they gave me whatever they had on hand.  Ah nuts! I've got 80' of this stuff to use up - and do a lot of twists with the smaller scale items like this. :-(

 

Well, lesson learned. I'll me more specific the next time I go shopping.

 

Cheers,

Neil

[Steve Sells]

hot rolled is a process;   this is not any type of grade or alloy.

A36 is a structural specification; not an alloy, and it can contain most anything as long as breakage and stretch limits are met.

1018 is an alloy; standards state what may and may not be conmtained in the melt.

 

sometimes we need to be reminded of that, and we need to remember when we order.

[ThomasPowers]

Isn't it refreshing to be getting closer to the earlier days of the craft where a smith had to examine and test each new load of metal to know what they had and what it would be good for!

 

(Moxon mentions this in the 1703 edition of "Mechanics Exercises")

[Crunch]

Is 1018 typically much more expensive at the steel service centers than A36?

 

I never would have known to specify 1018 if I hadn't read this.

[Neil Blythin]

Apparently, I didn't know to specify either.

So I happened to call over to my local Metals Supermarket this afternoon. Generally, their cold rolled is 1018 and their hot rolled is A36. Not sure the cost difference, but will certainly specify 1018 next time.

[Steve Sells]

I get my 1095 and 1084 cold rolled...  just as an example

[Judson Yaggy]

Looks like low bid supplier steel to me.  It happens sometimes.  Cut it off, throw away, try again.  

 

Is there a locally owned and operated place you can buy steel?  Such a place may be more sympathetic when you bring your workpiece to them and say "This steel is c#$p."

[metalmangeler]

As noted not really that suitable for what you are using it for, however it really should be good for another smithing project so get what will work for your twists and you will have an inventory of stock for the other projects that need 3/8 sq. If we had unlimited funds these problems would not bug us so much, but I sure try to not get more worked up than nessisary over stuff like this.

[New2Smithn]

I have had this same issue with a railaoad spike before but thought i may have let it get to cool during the process

[NeatGuy]

Try reliving the corners a bit with a hammer, a file or grinder before twisting it. I find twisting cold with relived corners can sometimes eliminate the cracks. It might be worth the effort instead of chucking the stock in the scrap bin.

 

brad

[lupiphile]

I'll break from everybody else, and bet it's your coal. I still have about 5 bags of otherwise fine bituminous, that without a careful coking , cracks my metal everytime. I keep it around to prove to people that, some times it really is the coal's fault........Take care, matt

[New2Smithn]

Lupiphile i do recall reading somewhere,maybe in one of my books that there were two different things that low grade coal could contain too high a content of,dont remember right off what they were but one could potentially cause the iron to become hot short and the other could make it cold short meaning it could fracture in the higher temp range or after it had cooled it could fracture.I will dig around later on and see if i can find it and if so will post the info.

[ThomasPowers]

Most common causes of Hot Short/Cold Short is too much Sulfur and too much Phosphorus.  Cold shortness is a function of too much Phosphorus.  Hot shortness; aka red shortness is a function of too much sulfur.  You can have both present making the steel hard to work at any temperature!

 

Note that manganese is added to steel to help scavenge sulfur that may creep in through the smelting process using coke.

[Neil Blythin]

Likely not the cause in this case Matt (as I was using a gas forge); but that's good to keep in mind if anyone runs into similar issues with a solid fuel forge. Thanks!

[mtforge]

We ran into this starting about two years ago when bending 1/2" square A36 into a u shape then flattened. We tried different techniques and finally came up with bending it at a lower temperature. We used to bend it at a bright red to low orange but started getting cracks that looked like yours. This was done in a gas forge, the same way for years. I could use 1018 cold rolled but the cost is at least three times the cost and I go through tons of it.

[anvil]

first rule of blacksmithing,,, get it hot. when its
yellow its mellow, when its red its dead.

a very good Santa Fe smith had this written on all his hoods.

serious, here, if you are going to get to an orange, not hot enough, leave it in a few seconds longer, get it yellow, and only do it once.

[anvil]

one more thing, yes it can be twisted cold but you are limited to the amount of twists per inch or it will crack or shear. at a yellow heat you can separate your look from that of the cold work guys and double or triple the amount of twist without cracking,,, no matter what kind of steel you use or how powerful your twister.

PLEASE NOTE! this is no critique for how you do your work, just adding info to a problem.

[mtforge]

first rule of blacksmithing,,, get it hot. when its
yellow its mellow, when its red its dead.

a very good Santa Fe smith had this written on all his hoods.

serious, here, if you are going to get to an orange, not hot enough, leave it in a few seconds longer, get it yellow, and only do it once.

When we got it over orange, into the yellow, it cracked worse. Getting it hotter doesn't work for the iron I'm getting any more. I guess I'm making new rules. This is for products I've been making for years.