How to distinguish stainless steel from stainless iron in pipes and fittings

I’m not sure if magnets will work; I encountered a similar issue in a previous project. After testing, the composition of various elements met the standards for 316L, but magnets still attracted to it. I wonder if this is stainless steel.

I checked online, and there are portable handheld metal analyzers that are like a handle* attached to them, which is very convenient. I heard that experienced workers can tell just by listening to the sound, but I’m not sure if that’s true or not

Does \"stainless iron\" refer to ferritic stainless steel? There is a liquid that can be used to test austenitic stainless steel; I don’t know exactly what it is, but I’ve seen it used by people who collect scrap. Here is the information from Baidu: The density of carbon steel is slightly higher than that of ferritic and martensitic stainless steels, but slightly lower than that of austenitic stainless steels ； The resistivity increases in the order of carbon steel, ferritic stainless steels, martensitic stainless steels, and austenitic stainless steels ； The order of linear expansion coefficients is similar as well, with austenitic stainless steels having the highest value and carbon steels the lowest ； Carbon steel, ferritic, and martensitic stainless steels are magnetic, while austenitic stainless steels are non-magnetic. However, they become magnetic when cold working induces a martensitic phase transformation; this martensitic structure can be eliminated through heat treatment to restore their non-magnetic properties.

Stainless steel cannot be attracted by magnets, whereas stainless iron can be. What is commonly referred to as stainless iron is actually non-austenitic stainless steel, and it possesses a certain degree of magnetism; in other words, stainless iron refers to stainless steel that is magnetic

It is somewhat feasible to identify them using magnets, as ferritic stainless steel is magnetic. Austenitic stainless steels are generally non-magnetic or exhibit only weak magnetism. There is a solution that can detect the presence of nickel in stainless steel; ferritic stainless steel generally does not contain nickel, so this allows for an easy distinction, and such a solution is quite inexpensive. That said, if there are still manufacturers using ferritic stainless steel to pass it off as austenitic stainless steel, then such fraudulent tactics are truly outdated – they belong to a time from 10 years ago. Today, unscrupulous merchants generally use low-quality 201 stainless steel to pass off as 304; both are austenitic stainless steels, non-magnetic, and have similar appearances. .

There seem to be several methods: 1. Test for magnetism; stainless steel generally has no magnetism. 2. Using a spectrometer, it is very accurate. 3. There’s also something like chemical reagent testing; I’m not very familiar with that either.

Just perform a spectral identification; it’s very simple.

We often encounter this problem as well; it’s really frustrating. We can’t just buy some materials and then have them tested, right? There’s a certain solution claimed to be able to conduct such tests, but it’s not clear whether it’s genuine or not

I’ve learned it; a regular magnet should work, right?

Stainless iron is a type of stainless steel. Stainless steel does not rust because it contains chromium in its composition. The entire category of stainless steels can be divided into four main types: First, martensitic stainless steels: these are stainless steels to which chromium is added directly; they are magnetic and require heat treatment to produce highly strong martensite structures with a needle-like microstructure. Second, ferritic stainless steels: these also contain chromium added directly, are magnetic, but do not require heat treatment; ferritic phases are present in them. Third, austenitic stainless steels: these contain chromium and nickel; they are non-magnetic and do not require heat treatment. After quenching, the austenitic structure becomes very tough, highly ductile, and possesses considerable strength. Fourth, precipitation-hardening stainless steels (duplex stainless steels): these steels contain both martensitic and austenitic structures. In terms of price, stainless steel is generally more expensive than cast iron. The term commonly used for \"stainless iron\" refers to non-austenitic stainless steels, which possess a certain degree of magnetism. In other words, stainless iron is stainless steel that is magnetic; its microstructure consists of ferrite and martensite, whereas the microstructure of ordinary stainless steels is austenite. Martensitic and ferritic stainless steels are what people colloquially call \"stainless iron\"”