So my general understanding as to why iron over-took bronze as the main material for weapons and armor has not only to do with its superior qualities but as well as its abundance and accessibility to ore. Given that historians generally date the start of the Iron age to around the 12th century BC why in the 5th 4th and even 3rd centuries BC we still see bronze being used regularly in chest plates, shields (most notably the aspis) and helmets. With iron, armor would be cheaper, lighter, and stronger, so why do we still see this proliferation of bronze? My only guesses are that it was maybe a sign of wealth to be able to use bronze? Or was bronze cheaper given that it's easier to mold and cast than iron despite the difficulty in acquiring tin?
Bronze is in many ways better than iron. Comparing the commonly-used 10% tin bronze (90% copper, 10% tin) with low-carbon iron/steel (1006 low-carbon steel, with 0.06% carbon):
| . | Bronze | Iron |
|---|---|---|
| Hardness (Rockwell B) | 55 | 49 |
| Tensile strength | 260-450MPa | 295MPa |
| Elongation at break | 50% | 30% |
The higher hardness means that a bronze blade will stay sharper for longer. Bronze blades sometimes used high-tin alloys for an even higher hardness (this was common in East Asia), and edges were work-hardened to produce higher hardnesses. The variation in the tensile strength above is because the tensile strength depends on the heat treatment of bronze. A higher tensile strength and elongation at break, together with the higher hardness, means that bronze armour is more effective. The 1006 low-carbon steel above is a modern steel, with far fewer slag inclusions than ancient steel - ancient iron might only have about 2/3 to 3/4 the strength of modern 1006 steel.
Bronze has another advantage when making large thin objects, such as plate cuirasses, helmets, greaves, shield facings, etc.: it can be cold-forged. This means that a large thin workpiece can be forged at room temperature, with no problems with it cooling below forging temperature, or the bronzesmith burning himself on it. There are very good reasons why bronze armour with large thin plates preceded iron plate armour by a long time.
Finally, bronze is much more corrosion resistant.
Iron has one very important advantage: once iron-making technology is well-established, iron is typically much cheaper than bronze. This meant that iron armour should have been cheaper than bronze armour, but the difficulty of making large thin plates/sheets of iron mean that bronze continued to be used for plate armour. Iron was suitable for making scale, lamellar, and mail armour.
Once steel (rather than low-carbon iron) could be reliably made, and quench-hardening of steel was established, hardened steel was superior to bronze for bladed weapons (and tools). And, of course, also superior to iron bladed weapons and tools. However, despite this superiority, iron continued to be used for cheap cutting tools, and even for swords (to about the end of the first millennium AD in Europe). Despite not being as good, iron blades were still effective enough to be used.