Is it or isn't it stainless?

[hooblah]

I've bought a supposedly stainless steel pipe fitting. There are some small brown marks on it which is quite possibly rust, and a magnet sticks to it. Certain grades of stainless can go rusty and are magnetic, which can make things confusing. Is there another way I can identify if this is mild or stainless?

 

[cheb]

My test is how well I feel the magnet sticks to it. Hard and it's mild, just and it's 304/A2, and if not it's 316/A4.

 

[Barking Mat]

A2 is mildly magnetic, A4 isnt.

But I've already discussed this on here, and it's way more complicated I 'seem to remember'.

 

[Barking Mat]

316 / A4 is marine and food standard.

 

[hooblah]

Hmm so is judging how hard the magnet sticks to it the only way without getting too technical?

 

[roofman]

Recycled Steel identification

How to use the spark test method to identify various types of recycled steel.

www.tharwavalleyforge.com

hit it with a grinder

 

[Ross365]

Austenitics (300 series, with best corrosion resistance) non-magnetic, ferritic series (never used them, less good corrosion resistance ) are magnetic.

 

[cheb]

Hmm so is judging how hard the magnet sticks to it the only way without getting too technical?

There's no doubt other and better ways but I only test for what I need to know.

 

[Barking Mat]

Austenitics (300 series, with best corrosion resistance) non-magnetic, ferritic series (never used them, less good corrosion resistance ) are magnetic.

That's the word I was looking for, but couldn't find, like my keys.

 

[optima21]

if they are 409 grade stainless they will be magnetic as thats a ferritic grade

 

[MetalMonkey]

if they are 409 grade stainless they will be magnetic as thats a ferritic grade

They also rust and stain quite well too!

 

[Hitch]

The colour can be a good indicator.
What sort of pipe fitting is it?

 

[Barking Mat]

Does it actually matter ?

What's the application ?

 

[hooblah]

It's a hydraulic quick release fitting. I'm reluctant to start grinding it.

It was sold to me as stainless but I can't be certain. The finish is smooth and dull, and I can't tell if it's plated or not.

 

[Screwdriver]

You have to wonder if it's a specialised hydraulic fitting, would anyone even make a mild steel version?

 

[Gritineye]

It maybe a fitting subject to fatigue, a long time ago I had a 3.5 Mazda diesel engine fitted to a LR, I was shocked when the SS exhaust quickly went quite rusty. I was told it was a less brittle grade that would put up with the vibrations.

The exhaust was still fine and hadn't rusted any more when I sold it around 18 yrs later.

 

[hotponyshoes]

Plenty of the stainless grades are magnetic,
Bearings, kitchen knives, rulers, etc..
Get a piece of mild steel the same thickness and you should find that the magnet sticks to that a lot better.


Most pipe fittings have the grade on them somewhere (on the mass produced ones)
Hydraulic fittings etc may often be called stainless when frequently the parts in contact with the fluid will be one grade and the other bits something else.

They will also carry contamination rust very easily.
If it's been tightened with a pair of steel stilsons, or even held in a steel chuck/vice during manafacture.

I quite often see "rust" on 316 marine grade stainless. It's normally on some expensive custom made part on a boat when somebody is asking me if they have been charged for something and given something else. It's generally from contamination during construction and fine once cleaned off.

If you have some accurate scales and an accurate measuring jug you could probably work out if it's stainless or steel.

 

[hooblah]

Density... Good shout

 

[Smallfry]

Even the marine grades will dissolve in seawater eventually.

 

[Pigeon_Droppings2]

They will also carry contamination rust very easily.

My mate was saying he has separate spanners for stainless...I thought he was pulling my leg but did some reading and turned out to be a good idea.