U-lock or Disc lock?

[celticdog]

For hardening - the chains without any case hardening are also easy to cut with bolt cutters.
The trick is optimal hardness. Something Abus gets quite right with their Granig X-plus series of chains, U-locks etc. Not sure about other brands, since very few of quality are imported / available in my country.

Nothing is really theft proof, given enough time. Materials that can't be cut relatively easily with a grinder and the proper disk/blade aren't going to be cheap, They're also very brittle and hard to work with, and/or extremely heavy. However good chain link design helps by making it difficult to get a good angle and purchase on the chain when cutting through it.


High carbon, high molybdenum steel is harder to cut with an angle grinder. The addition of carbide further wears  the blade, slowing progress. The problem with high strength is increased brittleness. You'd have to use a fairly thick cross section and design it in such a way that it would be difficult to strike with force or difficult to pry apart with a jack. Steel like this isn't cheap and is hard to work with than other steels. It's a trade off between being saw and grinder resistant but more vulnerable to cutting torch or impact force.


Making a chain that can't be cut with a diamond wheel on an angle grinder is a tall order. The paradox being in order to make a chain the metal must be workable, so the same means used to produce it can be used to defeat it, i.e. mechanical force and or heat. Buy the best you can afford.