Why is my wrench turning black

My guess, messed up chrome plating.

If it even is proper chrome plating, with nickel underneath....sounds like just a "flash" of something...maybe chromium, maybe not.

I dont see how you can call it a piece of crap if it is a really nice wrench. It's one or the other or neither, but it can't be both.

Maybe it's a nice bit of crap?

Probably oxidation. Not much chromium in the steel to prevent it.

metallurgy) Any of several strong, hard alloy steels containing 0.15-0.25% vanadium, 0.50-1% chromium, and 0.45-0.55% carbon. Also known as chrome-vanadium steel.

a.. 8650 is the most common grade in use throughout the U.S. and the Far East. It does not have the hardness or ductility of Protanium® Steel a.. Chrome Vanadium is about comparable in quality to 8650. It is used primarily in Europe. a.. Chrome Moly is similar to Chrome Vanadium, but is somewhat stronger and harder. Because it is fairly expensive, manufacturers generally only use it on their higher grade and higher priced tools like ball head products, and substitute lower grades for their other tools. Europe and Japan are the primary users.

Chromium vanadium steel is not plated. It is just the name of a specific alloy.

Yeah I can't really think of why it would be turning. Maybe the alloys are modifying the rusting. Iron Oxide is black too, and there is some blue underneath it too. Vanadium and Chrome don't turn black and vanadium is toxic to boot as an oxide. Like I said it looks like it has been heated - that blue/black/greenish color that copper pipes turn when heated. It's only where I touch the wrench - the handle and the head - but not the flat part of the handle where the name is stamped.

Oh well not the end of the world, just wondering really.

You can't define "strength" and "hardness" of a steel based on alloy content. Alloys are used to enhance hardenability. Physical properties are developed through appropriate heat treatment where these alloys have an effect. Ultimate properties are a function of carbon content.

The noted levels of alloy have no significant effect on corrosion properties.

In a hardenable grade, as hardness increases, ductility decreases, just like a pretty good wrench can't be a piece of crap. :)

OK but we did not talk about or question strength; this was a definition copied. . So, your answer to the original question is . . . . . . ?

There's no reason why it couldn't be plated (although it sounds like the OPs wrench isn't).

Chromium Vanadium steel isn't a specific alloy...it's part of the AISI

I wasn't addressing the original question. I was correcting your post which dealt with those things.

I suspect the OP has an unplated or black-oxide coated wrench that is smutting as a result of the effects of his sweat on the handle.

Would that be oxidation?

Of course. There aren't many other mechanisms that cause iron to change color.

I don't believe you're correct here. But I'm really not interested in getting into it with you because I suspect it wouldn't prove fruitful for either.

I'm sorry I asked the question.

I don't think there's a reason for YOU to be miffed. You didn't indicate in your original post what type of coating your wrench had, if any. Others, including me, spoke of plating.

High priced wrenches can have bright chromium finishes underlain by one or even two layers of nickel. Cheaper tools my have just a "flash" amount of chromium. Still cheaper may have zinc. Others may have nothing.

My responses were directed at the metallurgical information provided by Edwin that, while true to an extent, contained some misinformation.

It isn't a matter of "getting into it with anyone". It IS true that bare steel, or steel that is poorly protected, can discolor or smut from exposure to moisture, especially sweat.