Crumbling steel?

[lyuv]

Tried to forge weld two 1/2" bars. Hammering it, at what I thought was welding temp, the steel started to crack and crumble. How is that possible?

Some info:

1. I"m a lousy welder, and poor judge of temp.

2. It's possible I got to burning. The lump on the bottom is a piece that broke off the end of the bar(s), and it looks burnt. BUT - the rest of the bar is just cracked, and that's the issue. It kept fracturing and falling apart.

3. The steel is a car's coil spring. Can it be some sort of steel that cant handle the heat? (at least in a blacksmith shop conditions)

[Latticino]

From picture it looks like you overheated the steel.  That is easier to do with high carbon steel than mild steel.  High carbon steel also welds at lower temperatures than mild.  Work clean and flat in the high orange range and a reducing flame and you will have better results.  Needless to say, using known metals will certainly help as well.

[ThomasPowers]

What he said and usually the higher alloy content it has, the more difficult it is to work with due to the limited working temperature range.  I "cottage cheesed" my first H-13 piece just trying to forge it.

Also why some alloys are difficult to forge weld as the welding temp of one is above the burning temp of another...

[Latticino]

I did exactly the same thing with my first try at H-13.  I had heard so much about how hard it was to work that I thought I had to heat it up to yellow/white to get it to move (in my defense I had been working with wrought earlier the same day....).  Boy was I surprised when it just about disintegrated before my eyes.  After I recovered I worked it at a bright orange under a power hammer and it did just fine.

BTW, if your coil spring is 5160, it is notorious for being difficult to forge weld to itself due to the high chromium content.  There are bunches of tricks to get around this, but the easiest may be to put a layer of sacrificial high carbon shim stock in between the two layers (1075 or 1095 will work well).

[Steve Sells]

who considers 0.8% to be a high percentage? I admit you need to use a flux

[JHCC]

2 hours ago, ThomasPowers said:

I "cottage cheesed" my first H-13 piece just trying to forge it.

Ditto with my first attempt at O1.

[Frosty]

I've had good results with spring steel by shining the joint faces on the belt grinder and oiling it immediately to prevent the chrome content from oxidizing. Then I dust the joint with flux before I wire or tack weld the joint, that's cold. The flux will melt and protect the joint as it heats up. I've found just above lemon yellow is a good temperature, high yellow tends to cause spring steel to cottage cheese like yours did.

I think if I were welding 1/2" sq. I'd find or make a low carbon canister then shine it all well and oil before closing it up in the canister. NO flux in a canister, a thin film of light oil like "3 in 1" works well for me. 

Once you get a handle on welding spring steel, O-1 is a piece of cake, you might screw one weld up . . . MAYBE. 

I've never messed with H-13 so have no comment. 

Frosty The Lucky.

 

[ThomasPowers]

I was NOT forge welding H-13; just forging a slitting chisel.  Though a nice H-13/D2 pattern welded blade.....

[Latticino]

I wasn't forge welding it either, just trying to forge a hammer eye punch.

[lyuv]

It may be my English, but I"m not sure what you guys mean when you say you got "cottage cheese". Do you mean burnt steel, or fractured?

If it's "fractured" - I"m confused. I assumed that as steel gets hotter, it gets softer and more malleable. Hence, less prone to crack under hammering.

I always "knew" that hotter = easier to work (up to the burning point, and beside the grain size issue). Is that true only for low carbon, or low alloy?

[RogerrogerD]

Looks like burnt carbon steel to me, caused by overheating.  Spring steel has highish carbon and more likely to “burn”.  Burning can cause “goops” of steel that look like “cottage cheese” to some people I guess. The burning effect will damage steel up the bar beyond the goopy stuff, which is why some is fracturing on you.  I’m guessing you were using a coke or coal forge rather than propane which is I think a bit cooler. If you are using a coal/coke forge, maybe get it nice and hot and them turn off or dont blow the air as you stick the steel in. Less oxygen I think you’ll be less likely to cause this effect. 

Also.. I am forced to have my forge outside, and its tricky to see the colour of the steel in sunlight. So I have burnt lots of steel, as I began blacksmithing. What looks an ok temp to forge in the sun is whitehot in the shade. Are you inside or outside? 

[JHCC]

5 hours ago, lyuv said:

It may be my English, but I"m not sure what you guys mean when you say you got "cottage cheese". Do you mean burnt steel, or fractured?

If it's "fractured" - I"m confused. I assumed that as steel gets hotter, it gets softer and more malleable. Hence, less prone to crack under hammering.

I always "knew" that hotter = easier to work (up to the burning point, and beside the grain size issue). Is that true only for low carbon, or low alloy?

Simple answer: Fractured, not burnt.

More complicated answer: while simple carbon steels can generally be worked in a full range of temperatures all the way up to just below burning, many alloy steels have an optimum forging range beyond which they should NOT be forged. This is called "hot-shortness", and it happens at higher temperatures when the alloying elements melt and form a thin liquid layer between the grains of the steel. This causes a loss of internal cohesiveness: any hammer blows at these higher temperatures will cause the steel grains (austenite, at these temperatures) to slide along that liquid layer rather than stick together. The result is the dreaded "cottage cheese" effect.

For example, O1 has a safe forging range of 1795F/980C to 1950F/1065C, which is roughly a bright orange to a medium yellow. If you forge any higher, you get this:

This was from forging at a bright yellow, around 2000F/1110C. There was no sparkling, and it was definitely not burning.

[JHCC]

44 minutes ago, RogerrogerD said:

Looks like burnt carbon steel to me, caused by overheating.

In this particular case, probably Yes. However, burning steel is not the same thing as hot shortness in alloy steels, which occurs at a lower temperature.

[ThomasPowers]

Hot short originally was used for steels containing significant amounts of sulfur in them which would form intergranular alloy layers that would melt at lower temps than regular forging. This became a problem when they started using coke for smelting of steels. The addition of Manganese to scavenge sulfur helped immensely!

Cold short was the opposite with the bad element being phosphorus (much more common in bog iron ores, though phosphorus is a hardening element in steel and high phosphorus iron was used for edge materials in Celtic swords "The Celtic Sword" Radomir Pleiner).

This is why steel specs almost always include a value for sulfur and phosphorus with "not to exceed" prefixed.

High alloy steels are not a uniform materials but include various "regions" of differing alloys, (a simple example is pearlite which has alternating layers of Cementite (FeC) and Ferrite). Some of these components have a lower melting temp than others and so when a piece is heated above their working temps it can crack or crumble under impact.

So in my case I over heated the H-13 and when I hit it it crumbled into little chunks  that were a lot like fine cottage cheese curds.  So Fractured I guess.

[Irondragon Forge ClayWorks]

7 hours ago, ThomasPowers said:

when a piece is heated above their working temps it can crack or crumble under impact.

Or just fall apart under the weight of both ends. That happened to me when heating a piece of hay rake tine. It was in the fire at the center of the curve with both ends sticking up. Don't know if I can find that post but the consensus was overheating without burning. Found the pictures. Looking at the first picture, I think there was a hot spot in the fire, possibly due to clinker.

[lyuv]

WHAAAAT???? 

Why did nobody tell me about this before? I have been struggling with crumbling steel (mainly O1) since I started blacsmithing, and especialy bladesmithing. I blamed working too cold (...). I blamed air blasting through the coal. Blamed the hammer

Seriously. That piece of information about hot shortness, is of top importance to any blacksmith working with steel. HUGE thank you to JHCC, Thomas and Irondragon.

To anyone who tutors novice blacksmiths - don't forget to teach this!

Edited April 3, 2019 by Mod34
Edited for inappropriate language

[Latticino]

Hmmm, left out again, even though I was first in with essential the same response.  Story of my life...

[ThomasPowers]

I don't have "novice blacksmiths" work with High C/High alloy steels.  I wait till they have proper hammer control and good temperature control.  *BECAUSE* they generally have difficulties working with it (And why I consider bladesmithing a more advanced skill; hard to stick limited temperature ranges in when folks are still having trouble hitting the same place twice and on the flat!.  For sadistic amusement have a student work alternatively Wrought iron and H-13 in the same solid fuel forge. Coming into Blacksmithing from knifemaking it takes an act of will  to heat WI to the temps it requires!)

[Frosty]

4 hours ago, lyuv said:

Why did nobody tell me about this before?

Because you maybe trusted the internet rather than books to learn about the blacksmith's craft?  Most books don't go into the metallurgical fine detail Thomas just did but most aren't written by folk with a degree or two in metallurgy and the material sciences. The internet is largely filled with the opinions of beginners and is a poor place to do research until you know enough about a subject to filter the good from the bad. OR you're a natural skeptic and vet everything you read online.

The books I "used to" have dealt with evaluating the steel under your hammer, not what to buy. A good rule of thumb when you're using salvaged steel is; "If something goes wrong with the work, try something different next time." "Cottage cheese," is a descriptive phrase for what hot short steel looks like in failure mode. Crumbled is I think a more common label in the older texts. 

Anyway, if you're using salvaged steels you want to buy or check out from a library some of the old blacksmithing books. The techniques for evaluating the working properties of found steel are tried and true from centuries of hands on experience.

Frosty The Lucky.

[ThomasPowers]

The old texts talk about testing every new shipment of iron to see how it works, like Moxon's 1703 "Mechanicks Exercises".  If you use scrap today you still need to do so! If you are using new, good steel you need to read the specs for "forging temps" for them.

[Steve Sells]

I covered testing unknown steels in the pinned threads too., all one had to do was read them to know

[Frosty]

You sure did Steve and all a person needs do is read the sticky for most any question they have. Unfortunately spending time reading and taking note is old school. The accepted method now is to just shout your questions to the universe and . . . ? 

We're dinosaurs Brother. Wanna go mastodon hunting this season? I'm knapping a new point for my spear. Still have that big club?

Frosty The Lucky.

[ThomasPowers]

I'll start building a fire and making a spit!

[SLAG]

Mr. Frosty,

Has written,

"Anyway, if you're using salvaged steels you want to buy or check out from a library some of the old blacksmithing books. "

Good idea.

And another source for copies of those books is on line.

One such source,  out of many,  is the Missouri Blacksmiths Association site

Try, 

www,bamsite.org/books/books.html

SLAG.