ocrickard Posted November 19, 2008 Share Posted November 19, 2008 Hi everyone, A friend of mine recently lost the key to his U-Lock bicycle lock, and so we had to cut it with an angle grinder. I've got this long section of steel from it now that I straightened, and I was wondering if anyone knew what kind of steel is used in these things? It's made by Kryptonite, which are supposed to be almost impossible to break short of grinding them. Any ideas? This is the lock he had:Evolution series 4 Thanks, Oliver Quote Link to comment Share on other sites More sharing options...
orgtwister Posted November 19, 2008 Share Posted November 19, 2008 i'm not sure of that lock but most of them are case hardened just like the club steering wheel lock i was working as arecover agent and if you grab them in the middle (if your strong enough)and the end of the handle and pull in the midle and push on handle well i can bed them and pull the off it will crack the harding in the middle Quote Link to comment Share on other sites More sharing options...
petere76 Posted November 19, 2008 Share Posted November 19, 2008 Any idea what the difference is between case hardening and heat treating, or are they the same? Most of the lock shakles I have ground though thow off the visible high carbon sparks but I am still not sure of the metalurgy, maybe S-2 or S-7. I think they make the jaws for blt cutters out of S-7. Peter Quote Link to comment Share on other sites More sharing options...
hill.josh Posted November 19, 2008 Share Posted November 19, 2008 case hardening actually introduces more carbon into the steel therefore making it harder.. while heat treating as a whole either hardens or softens it depending on what you do but doesn't add any more carbon. Quote Link to comment Share on other sites More sharing options...
ThomasPowers Posted November 19, 2008 Share Posted November 19, 2008 (edited) When they claim something is case hardened they actually mean that it was processed to have an enhanced carbon content on the surface of the metal and then was hardened to make use of that layer. Heat treating covers a large number of different processes that have different results. Edited November 20, 2008 by ThomasPowers Quote Link to comment Share on other sites More sharing options...
petere76 Posted November 19, 2008 Share Posted November 19, 2008 Gents, thanks for the info. I will assume that the case harding is actually the addition of materials during the smelting of the steel as opposed to something done specifically during the heat treating cycle of the finished prodcut. As an example 4140 comes normalized and you work it then heat treat the finshed product. I recall a powder that could be spray coated on mild steel that was supposed to incur a surface hardening. The product did not work that well. Quote Link to comment Share on other sites More sharing options...
matt87 Posted November 19, 2008 Share Posted November 19, 2008 No, case-hardening is a process performed well after the smelting of the steel. Commercial products are available (e.g. Kasenite) that allow you to introduce carbon, nitrogen and possibly other chemicals into the surface of the object. They do work, but only as well as the limitations of the process itself. Example: I want to make a set of dies for a power-hammer. I use a piece of mild steel and it's too soft, so I decide to case-harden it. Now the surface is harder, but the steel underneath is still soft, so it slumps and I chuck the whole lot in the scrap bin and start again with a decent piece of tool steel. Quote Link to comment Share on other sites More sharing options...
ThomasPowers Posted November 20, 2008 Share Posted November 20, 2008 I recently case hardened some wrought iron about 100+ years after it was smelted; in fact I made blister steel from it. It can't be done when the metal is liquid so nope not during smelting. Case hardening can be a step in a heat treat process and does not really help for impact items; but rather wear/abrasion surfaces. Quote Link to comment Share on other sites More sharing options...
ocrickard Posted November 20, 2008 Author Share Posted November 20, 2008 I guess I'll just make some new tongs with it then - don't want to chance making a knife from it if it's mild steel. -Oliver Quote Link to comment Share on other sites More sharing options...
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