Galvanic series

[eddiesalita]

I've been reading back a bunch of old posts., as you do. And i've been wondering regarding soft iron cladding and the galvanic series.
Being a carpenter who has laid a number of copper roofs, used lead flashing and zinc coated steel etc... also familiar with boats and sacrificial anodes. The galvanic series is of fundamental importance when dealing with mixing metals.
It got me wondering about just how significant the sacrificial nature of the soft iron cladding is in reducing corrosion with nickel and chromium containingcarbon steel alloys. Or more particularly in forming a patina instead of a less passive oxidation process resulting in active rust?

Those with more experience in various claddings over carbon steel cores and the exact alloy of the soft iron used and how they react. Or with a deeper understanding of the galvanic series I would be interested on their thoughts as to whether this may be a possible reason for soft iron cladding other than the more well known traditional reasons.

[aporigine]

I've been reading back a bunch of old posts., as you do. And i've been wondering regarding soft iron cladding and the galvanic series.
Being a carpenter who has laid a number of copper roofs, used lead flashing and zinc coated steel etc... also familiar with boats and sacrificial anodes. The galvanic series is of fundamental importance when dealing with mixing metals.
It got me wondering about just how significant the sacrificial nature of the soft iron cladding is in reducing corrosion with nickel and chromium containingcarbon steel alloys. Or more particularly in forming a patina instead of a less passive oxidation process resulting in active rust?

Those with more experience in various claddings over carbon steel cores and the exact alloy of the soft iron used and how they react. Or with a deeper understanding of the galvanic series I would be interested on their thoughts as to whether this may be a possible reason for soft iron cladding other than the more well known traditional reasons.

Chemically, steel and iron both react electrocheically as … iron. There should be no change in potential across the weld.

Stainless steels get an out due to their thin dielectric armor.

I would be curious if the “rainbow Damascus” cladding on some knives has the liability. Copper and iron are a definite galvanic couple.

[ex1580]

I would be curious if the “rainbow Damascus” cladding on some knives has the liability. Copper and iron are a definite galvanic couple.

I have wondered this too. Rainbow damascus is pretty but what will it look like after a decade of use. I don't know much about this topic but I have seen pipes fail when the wrong metals are used together.

[gladius]

Saji Rainbow
After a few years she still cuts great...

[eddiesalita]

Copper and aluminium are especially reactive. I recall silver building wrap corroding almost completely overnight from copper roof runoff. Copper is also the reason we must use lead flashing on copper roofs, gutters and downpipes. And only copper or stainless fixings.

What do you mean by thin dialectic armor?

[aporigine]

Copper and aluminium are especially reactive. I recall silver building wrap corroding almost completely overnight from copper roof runoff. Copper is also the reason we must use lead flashing on copper roofs, gutters and downpipes. And only copper or stainless fixings.

What do you mean by thin dialectic armor?

Stainless is corrosion-resistant by virtue of a thin layer of chromium (III) oxide, a dielectric (insulator).

When copper-to-aluminum wiring happened in the 70s, regulators were quick to step in with specified Cu-to-Al connectors for the reason you state. Degrading connections tended to get hot. Such a steep galvanic potential does bad things to the more electropositive metal (Al.)

[Radar53]

Saji Rainbow
After a few years she still cuts great...

Verrrrrrrrrrrrrry nice as well