by Chupacabra » Sun Feb 03, 2008 6:59 pm
Hi Congalou,
In blacksmithing, to anneal something like steel, the blacksmith would heat the item to the prescribed temperature for a prescribed time. The variables depend on the grade of steel (amount of carbon), the amount, thickness and other factors. To indicate temperature you would use the colour of the steel when you heat it (need experience), or temperature indicating markers (foolproof). Technical specs on the steel are available from the suppliers. When the steel is annealed the grain is refined to the point where all the stresses are relieved, especially where the weld is. It also softens the steel, which wouldn't be desirable for a bell. This is where "normalizing" comes in. This process involves heating the steel to the prescribed temperature again (usually bright, cherry red) and quickly dipping it in brine, or just water and letting it cool in air. This reintroduces some hardness back to the steel and you have (insert technical term here) minimal stresses in the steel, which could affect the sound of the bell. These are just a couple of the basic techniques that the old, village blacksmiths have been practising for centuries!
There is also case-hardening but that's another topic!
If I had a shop to experiment in, this would be one of the first things I would try. It's costly, though. The price of acetylene is through the roof!
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