We’ve been getting a lot of requests from end-users about the operating temperature for our Golden Pin shackles.

So why is this a Titanic question?

It wasn’t the fact that Rose lost Jack Dawson or that Rose threw a perfectly priceless diamond over the stern of the ship many years after…

It is believed that a large contributing factor to the Titanic sinking was due to poor steel performance at cold temperatures.

Yes, the ship hit an iceberg and the musicians kept playing, however, the steel composition of the hull wasn’t equipped to handle cold temperature and became brittle and fractured. Had this happened in warmer water the outcome could have been vastly different.

Now that we have Rose and Jack out of the way we can talk more about why.

For the nerdier, here is a little information on the why.

There are a few elements that have a direct impact on steel in cold weather:

-Carbon

• The more carbon, the more brittle the steel. 

-Nickel

• Nickel increases hardenability and toughness, 

-Manganese

• Increased manganese, increase hardness. It’s also an Austenite stabilizer that lowers the eutectoid temperature, thereby expanding the austenite phase field (i.e., temperature range over which austenite is stable). I’ll be honest, this is above basic nerdy.

Why do we care about cold temperatures?

It is important because of the reaction of steel when subjected to cold temperatures.

Like what happened to the sinking of the Titanic the molecular state of the grain will change as the temperature drops causing a reduction in ductility/elongation. When this happens, the steel will no longer show as many signs before braking. Metals that are typically ductile at room temperature may lose that in the colder temperature and become stiffer and therefore brittle.

The brittle transition temperature is the temperature where fractures in steel change from ductile to brittle. In other words, instead of bending, it breaks. The temperatures will differentiate based on how the steel is composed, the profiles, and heat treating. If people are using steel below temperatures of -20 it means that an engineer cannot accurately predict the mode of failure in the low-temp zone. Any brittle failure will be catastrophic, but the failure won’t necessarily be predictable. It will be from a random impact, dynamic loading, or propagate out of a crack or nick.

Charpy impact test, or V-notch test, is utilized to determine the amount of energy absorbed by steel during a fracture. The energy absorbed gives a measurement of toughness and helps determine the brittle transition temp. Two criteria needed to run the test are the amount of load (in foot/pounds) and the temperature of the sample. The test is relatively quick and cost-effective. It confirms that the steel will be able to stand up in weather conditions required for the end-user.

Why don’t more factories do these tests?

• There is no requirement under the regulations to do this.
• There is no guarantee that you will be able to obtain the results to meet the requirements.

The way steel reacts at room temperatures will not give you any indications of how well it will perform at low temperatures. Meaning you can have a perfectly fine shackle that tests within specs but subject it to cold temps and it fails the DNV impact test. That’s another reason why they don’t do the test.

Meeting the 42 joules lets the user know the steel used here is still predictable.

• Our Golden Pin shackles can meet DNV impact requirements of 42 joules (31ft.lbs) at -20 degrees C (-4 degrees F)

For a lot of applications and as long as the user doesn’t push the safety factors there shouldn’t be an issue, however, a lot is riding on it.