From WoWWiki

To process raw ore into purer bars of the base metal or combine other smelted metals into an alloy such as Bronze. Requires a forge.

This is the primary sub-skill of the Mining profession.

Smelting Difficulty:

Metal	Orange	Yellow	Green	Gray	Ore Rarity	Ingredients
[Copper Bar]	1	25	50	70	Common	[Copper Ore]
[Tin Bar]	65	x	65	75	Common	[Tin Ore]
[Bronze Bar]	65	65	90	115	Alloy	Copper Bar + Tin Bar
[Silver Bar]	75	100	112	125	Uncommon Tin Vein	[Silver Ore]
[Iron Bar]	125	130	135	140	Common	[Iron Ore]
[Gold Bar]	155	170	177	185	Uncommon Iron or Mithril Deposit	[Gold Ore]
[Steel Bar]	165	x	x	165	Alloy	Iron Bar + [Coal]
[Mithril Bar]	175	175	205	230	Common	[Mithril Ore]
[Dark Iron Bar]	230				Common	8x [Dark Iron Ore] (at [Black Forge])
[Truesilver Bar]	230	x	x	230	Uncommon Mithril Deposit	[Truesilver Ore]
[Thorium Bar]	250	250	270	290	Common	[Thorium Ore]
[Elementium Bar]	1	x	x	x	Uncommon drop from Blackwing Technician in Blackwing Lair	[Elementium Ore] + 10x [Arcanite Bar] + [Fiery Core] + 3x [Elemental Flux]
Burning Crusade
[Fel Iron Bar]	300	300	307	315		2x [Fel Iron Ore]
[Adamantite Bar]	325	325	332	340		2x [Adamantite Ore]
[Eternium Bar]	350	350	357	365		2x [Eternium Ore]
[Felsteel Bar]	350	355	367	x		3x Fel Iron Bar + 2x [Eternium Bar]
[Khorium Bar]	375	x	x	x		2x [Khorium Ore]
[Hardened Adamantite Bar]	375	x	x	x		10x Adamantite Bar

v • d • e Metal bars Azeroth Copper • Tin • Bronze • Silver • Iron • Gold • Steel • Mithril • Thorium • Truesilver • Dark Iron • Elementium Outland Fel Iron • Adamantite • Eternium • Felsteel • Khorium • Hardened Adamantite • Hardened Khorium Northrend Cobalt Non-smelted Enchanted Thorium • Arcanite