Cast iron skillet breaking in two

[Dawgluver]

OK, I'm also a member of a different cooking forum, and one of the members said her Griswold CI skillet broke in half after she put ground beef in it. It's over 30 years old, and she didn't put it in the fridge or use any cold stuff with it. I've not heard of this, other than the skillet is defective. Ideas?

 

[Andy M.]

Over 30 years that skillet suffered many minor and some major trauma that weakened the metal over the years and finally developed into a crack and split. It wasn't the hamburg working alone.

 

[Dawgluver]

I have CI much older than the residents in the nursing homes here. I've never heard of it falling apart!

 

[jennyema]

It has nothing to do with the Hamburg.

If it happened it was probably a heat shock that caused prior defects to give way

 

[Kayelle]

Many years ago, I had a CI skillet that developed a leaking crack and needed to be discarded. I have no idea why, but after that episode I concluded that CI isn't all it's cracked up to be. Sorry, I couldn't help myself. Groan,

 

[RPCookin]

Not knowing the exact circumstances, all I can add is that cast iron is a very brittle metal. It will take very little stress or flexing to cause it to crack or break. If the pan had been previously mistreated, it could have had invisible stress fractures in the material. It may have been holding together by just a thin surface layer which finally gave out, with no fault going to the use in which it actually broke.

 

[Chief Longwind Of The North]

Cast iron is much like glass. It is not very malleable, that is, it doesn't bend well. It tends to fail catastrophically when it does fail. Griswold pans were very popular due to the thinner metal of the pan, and the smooth cooking surface. It was lighter than most of its competitors. This made the brand subject to more failure from thermal shock as well.

What happens with thermal shock is that the outer surface of a material begins to heat up. If that material is a poor conductor of heat, that surface expands faster than does the middle of the material, and the inside surface. As the material, be it glass, ceramic, or cast iron does not readily bend, the enormous stress of the outer expansion, and the immovable inner material creates tremendous pressures that can cause the material for fail, i.e. crack of fracture. In extreme cases, the metal can fail violently.

Cast iron is tough, and usually will last multiple lifetimes. But like all things made by humans, it is less than perfect.

Very hard carbon steel pans can suffer similar issues if treated to heavy enough thermal shock, though steel of any kind bends better than does cast iron, and so usually warps from thermal stress rather than shatter.

Seeeeeeeya; Chief Longwind of the North

 

[puffin3]

Many years ago I inherited my grandmother's cast iron kettle.
Took it on a moose hunting trip. A thin layer of ice formed overnight on the lake beside where we had set up camp.
I tied a rope onto the kettle's handle and threw the kettle a few feet out unto the ice to break it the ice and have the kettle fill with drinking water.
When the kettle hit the thin ice there was a 'ping' sound. I pulled on the rope and retrieved the kettle which had broken into two pieces.

 

[tenspeed]

Perhaps there’s a metallurgist or materials engineer in the house that can shed more light on this, but failure due to thermal shock is a generally a result of rapid cooling (e.g. putting a hot pan in cold water), rather than rapid heating, especially in a household environment. Rapid cooling puts the surface of the object in tension (trying to shrink around an expanded core), and most materials are more likely to fail in tension rather than compression.

As compared to a lot of other materials, cast iron is regarded as has having good thermal shock resistance and is a fairly tough material. A lot of machine components are iron castings. There are a number of types and alloys of cast iron, and the thermal shock resistance varies among them. It’s been a few decades since I was in the metal removal industry, so I’ve forgotten a lot of details. By the way, machining metal can produce some red hot chips, and there is usually a flood of cooling water over the cutting area.

As far as the skillet breaking, I’ll guess that it was a result of previous abuse or a manufacturing defect. I can’t imagine how putting ground beef into it would cause a failure. Deglazing a pan would cause more rapid cooling than that.

 

[GotGarlic]

What if she had heated the pan and then put a hunk of frozen ground beef in it? (I'm asking out of curiosity; don't know that she did that.)

 

[tenspeed]

What if she had heated the pan and then put a hunk of frozen ground beef in it? (I'm asking out of curiosity; don't know that she did that.)

Best guess is that the ground beef isn't thermally conductive enough to cool the pan fast enough to generate the temperature differential needed to crack a pan. Put a frozen burger in a pan and most of it will remain frozen for quite a while. Liquid water, on the other hand, is a good thermal conductor and requires quite a bit of energy to go to the gaseous state (steam), and can cool the pan quite rapidly.

Think of how long it takes to heat a burger all the way through vs. how long it takes to boil off the water when deglazing a pan.

 

[GotGarlic]

Thanks

 

[Dawgluver]

The burger was defrosted.

Lots of interesting info here, thanks guys!

 

[CStanford]

CI is a brittle material as others have mentioned. It probably got a little hairline crack from banging against another CI pan or a drop. Over time the heating and cooling worked on the crack until it fractured all the way through.

 

[tenspeed]

Brittle is a relative term. There are a variety of types of cast iron. Remember, engine blocks, cylinder heads, and crankshafts are made from CI.

 

[Chief Longwind Of The North]

Perhaps there’s a metallurgist or materials engineer in the house that can shed more light on this, but failure due to thermal shock is a generally a result of rapid cooling (e.g. putting a hot pan in cold water), rather than rapid heating, especially in a household environment. Rapid cooling puts the surface of the object in tension (trying to shrink around an expanded core), and most materials are more likely to fail in tension rather than compression.

As compared to a lot of other materials, cast iron is regarded as has having good thermal shock resistance and is a fairly tough material. A lot of machine components are iron castings. There are a number of types and alloys of cast iron, and the thermal shock resistance varies among them. It’s been a few decades since I was in the metal removal industry, so I’ve forgotten a lot of details. By the way, machining metal can produce some red hot chips, and there is usually a flood of cooling water over the cutting area.

As far as the skillet breaking, I’ll guess that it was a result of previous abuse or a manufacturing defect. I can’t imagine how putting ground beef into it would cause a failure. Deglazing a pan would cause more rapid cooling than that.

I'm purposely mixing apples and oranges here. I had a chafing dish that came with two small candles, in holders, to keep food warm. The dish was made of tempered glass, not borosilicate glass. I replaced the candles, when used up with two cans of Sterno fuel to provide the heat under the chafing dish. I was preparing other parts of the meal, and had warm casserole type food (fice pilaf with chicken strips) in the chafing dish. The dish was on the dinner table and I was in the adjacent kitchen. I hear the pop of the glass shattering. There wasn't a single crack, but many chunks of glass littering my table, and impeded into the rice dish, which of course went into the trash.

I assumed that the glass was heating to quickly, and that as an insulator, the pressure built by differing rates of expansion cause the failure. I have seen glass pots, and dishes fail do to heating too quickly, especially if the heat is applied only to one surface. I would assume that the cast iron used in pans would react similarly. Though cast iron is a better conductor of heat than is glass, it is still a relatively poor heat conductor.

And yes, like you stated, rapid contraction of the metal will also cause it to fail. Most CI pans come with a warning not to throw a hot pan into cold water, so as to avoid failure of the metal.

The cause of my chafing dish failure was applying excessive heat to the dish bottom. I could see it happening with CI, though rarely.

Seeeeeeeya; Chief Longwind of the North

 

[roadfix]

Almost anything cast can over time develop cracks and eventually fail.

 

[tenspeed]

Fun facts:

According to

http://www.engineeringtoolbox.com/thermal-conductivity-d_429.html

aluminum has approx. 4 times the thermal conductivity of CI, and CI has approx. 50 times the thermal conductivity of glass.

Borosilicate glasses have a very low thermal coefficient of expansion (don't change much in size due to temperature changes), which is what makes them resistant to thermal shock.

 

[Chief Longwind Of The North]

Fun facts:

According to

http://www.engineeringtoolbox.com/thermal-conductivity-d_429.html

aluminum has approx. 4 times the thermal conductivity of CI, and CI has approx. 50 times the thermal conductivity of glass.

Borosilicate glasses have a very low thermal coefficient of expansion (don't change much in size due to temperature changes), which is what makes them resistant to thermal shock.

When Pyrex started using temperd glass for their cookware instead of borosilicate glass, I was highly disappointment.

By the way, just in case your'e wondering, I agree with you and just threw in the apples to oranges comparison to highlight that the issue is with rates of expansion.

Seeeeeeya; Chief Longwind of the North

 

[redclay13]

Simple case of old metal being hot and cold material put into it. After thirty years of who knows how it was used this is not unusual. One of those things that makes get party chatter.