Identification of rust in alloy steel

"advise how to eastablish chemically/scientifically the presence of

rust ON in alloy steel."

Copper sulfate will plate out pure copper film on clean bare steel. It will not produce a bright copper film on iron oxides. (rust is one form of iron oxide)

A weak solution of Copper sulfate applied onto the area will show bare steel by 'plating' a thin film of copper. where iron oxide is there will be no copper plate, only a damp stain.

I mixed 1 table spoon of copper sulfate crystals in 8 oz of water to make my solution.

Looking for about 10% concentration, more or less.

On the bar ends you can see indications of copper from the drops i put on it. If i had put them on the dark oxide sides of the bars, nothing would have happened save 'moistening' the material.

Milo

ooh, ooh ooh,, another GA for you. And another GA and another GA and another GA for you.

_{(Sung to the tune of "another one bits the dust")}

Many moons ago, my colleagues and I guffawed loudly when a major customer complained bitterly that our stainless steel pump was rusting. I think it was determined in the end that an iron fitting above the pump was dripping rust onto the suction flange, and all was forgotten.

More recently, I came across an occurence of rust IN stainless steel. I'm racking my brain trying to recall where, when and what. If it comes to me, I'll let you know.

What I can say is that any alloy steel (or alloy containing ferrite) can or will rust. The thing is that in most circumstances and under most conditions, it will happen so slowly that we and our childrens children will not live long enough to see it.

It is particularly the Chromium content, but also the Nickel content, that helps to prevent oxidation of the ferrite, both internally and externally. Grades and types of stainless steel (ferritic more so than martensitic) may have less resistance to ferrite oxidation than the common austenitic stainless steels such as AISI 316, mostly due to lower Cr content.

However, the term 'Alloy Steel' goes way beyond the common stainless steels, and high Chrome/Nickel alloys. It also includes the 'low alloy steels', such as AISI 4140, which is a very common alloy steel, but with only approx 1% Chromium, it can be very prone to ferrite oxidation (rust).

I am not an expert in this field, but I am sure you can get more information from organisations such as AISI, NACE, etc.