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Products like Hawkins Contura Black Pressure Cooker are hard anodised but haven't specified the metal used in the body, here. Others explicitly mention they are made from anodised aluminium.

I want to know whether hard anodising a metal (aluminum in this case) makes it stronger than steel? Steel doesn't get a dent if it falls from a height, can the same be said regarding this hard Andonised Aluminum?

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    "Steel doesn't get a dent if it falls from a height"....that seems like an absurd test...how thick is the steel, how high is the fall, what is it falling on? – rfusca Apr 3 '12 at 17:13
  • @rfusca Assumption was the steel used in those pressure cookers, and falling distance was from the kitchen shelf on the cemented floor. – Aquarius_Girl Apr 4 '12 at 1:07
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Anodizing is a surface treatment that thickens the natural oxide layer of a piece of metal. Aluminum is the most commonly used metal that is anodized, but magnezium, zinc, and some other metals can also be anodized. Steel can not be effectively anodized.

So any description of pots and pans that uses "anodized" is almost certainly referring to aluminum.

It doesn't change the strength of the metal, only the surface properties - corrosion resistance, colour, etc.

Hard anodizing creates a thicker layer of oxide than "normal" anodizing, but it's still a surface treatment, it doesn't change the strength of the metal.

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  • that means if the hard andonised aluminium lid falls from the kitchen shelf on the cememted floor, it may get a dent? – Aquarius_Girl Apr 4 '12 at 1:09
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    It means that the anodizing won't make any difference - whether or not the lid gets dented depends only on how thick it is, how high it falls from, and what part of it hits the floor. – Ward - Reinstate Monica Apr 4 '12 at 2:02
  • Actually hawkinscookers.com/1.5.pc_what_HA_is.html talks about the durability of the hard andonized metals, so I was confused. – Aquarius_Girl Apr 4 '12 at 6:40
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'Durability' means a lot of different things, as it's concept of how well things last over time.

'Strength' actually has a specific meaning in material science, as it's the amount of force per area something can take without causing significant plastic deformation. (ie, it doesn't bounce back when the load's removed)

'Toughness' is the amount of energy required before fracture, and because aluminium deforms to absorb energy, it's considered tougher than steel by weight in most conditions.

Annodizing can improve these two measurements (although, if I remember my classes, it's brittle so it'd help in compression not tension), but what we mostly care about is it changes the surface characteristics is improve the 'hardness' (likelihood of scratching for the most part) and changes its corrosion characteristics (eg, how it behaves in contact with acids).

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