|Rusty iron plate.|
Just some old iron pulled from a junk pile at the farm. The sound is steel plate like this being beaten with a blacksmith's hammer.
See hafnium for some pictures of a plasma-arc cutting torch cutting some steel plate much like this, and see oxygen for a story about how oxyacetylene cutting torches actually work.
Source: Marco's Scrap Metal
Contributor: Theodore Gray
Acquired: 15 April, 2002
Text Updated: 29 January, 2009
Price: $0.10/pound for scrap iron.