Stainless steel — ferrous or non-ferrous metal
Which metal stainless steel is is a question of classification, not of properties. Stainless steel is an alloy based on iron, so in the industry classification it belongs to the ferrous metals.
Chromium, nickel and molybdenum, which are part of its composition, are themselves non-ferrous, but in the alloy they are alloying additions, not the base.
Below we will examine how the classification of metals is arranged, why stainless steel is stubbornly listed as non-ferrous, and what follows from this when purchasing and handing in scrap.
Classification of metals
All metals are divided into two large groups. Ferrous — alloys based on iron: steel, cast iron, ferroalloys. Non-ferrous — everything else: copper, aluminium, lead, zinc, tin, nickel, titanium, magnesium, as well as the precious metals. The division is practical: the two streams have different ores, different metallurgy, different warehouses and different receiving points.
| Criterion | Ferrous metals | Non-ferrous metals |
|---|---|---|
| Base of the alloy | iron | any metal except iron |
| Examples | steel, cast iron | copper, aluminium, nickel, titanium, zinc |
| Magnetism | more often magnetic | more often not magnetic |
| Volume of production | mass-scale | smaller by mass |
| Scrap acceptance | ferrous scrap | non-ferrous scrap |
Within the non-ferrous metals there is also a division: heavy, light, refractory, precious, rare-earth. For buying rolled steel this detail is almost unnecessary, but the boundary between ferrous and non-ferrous is important: it is where accounting, scrap acceptance and customs classification begin.
Where stainless steel fits
Stainless steel is steel. Its base is iron, and chromium, nickel and molybdenum are added in such quantities as to obtain corrosion resistance. By the basic criterion "what the alloy is based on" it unambiguously falls into the ferrous metals, like any other steel.
The alloying elements confuse the issue. Chromium, nickel and molybdenum are mined and sold as non-ferrous metals, and their share in the composition of stainless steel is noticeable. But the classification looks at the base, not at the additions. By the same logic brass remains a non-ferrous metal, although in some grades it may contain more zinc than copper.
In the customs classification, stainless steel products also fall under the sections reserved for ferrous metals. Chapter 72 covers flat and long products, including sheet, round bar and angle, chapter 73 — pipes and articles. The HS codes from the exchange catalogue look like this.
| HS code | What it encodes | Type of rolled product |
|---|---|---|
| 730640 | round welded pipes | round pipe |
| 730661 | profile welded pipes | profile pipe |
| 721922, 721923, 721932, 721933, 721934 | flat products | sheet |
| 722211, 722220 | bars | round bar |
| 722240 | angles and profiles | angle |
The code is chosen for the specific type and size of rolled product, and it does not change depending on whether the material is called non-ferrous or ferrous in correspondence. In more detail — in the analysis of HS codes.
Why people confuse them
The first reason is scrap. Stainless steel is often handled as a separate stream on acceptance, and in price it is closer to non-ferrous than to ordinary steel, because it contains nickel and chromium. Hence the habit of saying "I handed in non-ferrous", although formally steel has been handed in. The price of scrap depends on the grade and condition, not on the name of the group.
The second reason is the magnet. Many are sure that a ferrous metal must be magnetic, while stainless steel after annealing hardly reacts to a magnet. But magnetism is a sign of structure, not of the metal group. Austenitic grades are weakly magnetic, ferritic and martensitic grades are strongly magnetic, and all of them remain steel.
The third reason is appearance and behaviour. Stainless steel shines, does not become covered with red corrosion and does not look like the familiar "black steel". On top of that it is often sold where non-ferrous products are sold. All of these are everyday signs that have nothing to do with the classification.
What this changes when purchasing
For the choice of metal — almost nothing. For the buyer what matters is the grade, the size, the surface, the standard and the condition of the edge. The name of the group in the specification affects neither the strength, nor the weldability, nor the resistance to the environment. A dispute about whether this metal is non-ferrous or ferrous will not help you choose between 304 and 316L.
| What changes | How to take it into account |
|---|---|
| Warehouse accounting | stainless steel is stored separately from carbon steel to avoid surface contamination |
| Scrap acceptance | a separate stream and separate requirements for grade and cleanliness |
| Customs | the HS code is chosen by type of rolled product, not by metal group |
| Certificates | the grade and the analysis of the batch are checked, not the name of the group |
| Price | depends on the grade, size, surface and volume of the batch |
The practical conclusion is simple. In the contract and the order you write the type of rolled product, the grade and the size — that is enough for an unambiguous delivery. And if you are handing in scrap, ask at the receiving point which stream they accept stainless steel in: the paperwork procedure depends on this, but not the classification itself.
Frequently asked questions
Does stainless steel belong to the ferrous or the non-ferrous metals
To the ferrous. The base of stainless steel is iron, as with any other steel. Alloying additions do not affect the group.
Stainless steel is a non-ferrous metal
No. People say this in everyday speech because the composition contains nickel and chromium, and stainless scrap is accepted separately from ferrous scrap. Formally it is steel, that is, a ferrous metal.
Why is stainless steel sometimes considered a non-ferrous metal
Because of scrap and appearance. It is accepted as a separate stream, it is not magnetic and does not rust, so it does not look like familiar carbon steel. These are practical signs, not a classification.
Stainless steel is not magnetic, so it is not steel
Magnetism depends on the structure. Austenitic grades after annealing are weakly magnetic, after cold deformation they are noticeably more magnetic. Ferritic grades are always magnetic. A magnet test does not replace a composition analysis.
How is stainless steel scrap handed in
As a separate stream, with the grade stated and an assessment of cleanliness. The price depends on the grade, condition and volume, so the scrap is sorted rather than mixed with carbon steel. More about acceptance — in the section stainless steel scrap.
Does the classification affect the choice of grade
No. The grade is chosen by environment: 304 for water and food, 316L for chlorides and acids, 201 and 430 for dry conditions and decor. What exactly this steel is by composition we examine in the article what stainless steel is.
What to do next
Classification does not hinder delivery: in an order on the GCX exchange you state the type of rolled product, the grade, the size, the surface and the shipment week. On sale — pipe, sheet, round bar and angle made of grades AISI 201, 304, 316L and 430.