Stainless Steel and Acid-Resistant Steel — Common Terms, Real Differences
Many customers bring steel components to the scrap yard, referring to them broadly as "stainless." This is an understandable simplification, but in practice it makes a significant difference in the scrap trade. Stainless steel and acid-resistant steel are two distinct types of alloys that differ in chemical composition, functional properties, and — crucially from the seller's perspective — their value on the secondary raw materials market.
What Exactly Is Stainless Steel?
Stainless steel is a broad term covering iron alloys with a minimum chromium content of 10.5%. Chromium forms a thin oxide layer on the surface that protects the metal from rust under typical atmospheric conditions. This is sufficient for everyday applications: cutlery, kitchen equipment components, household appliance housings, railings, and plumbing pipes.
The most popular group of stainless steels is the austenitic 300 series, with grade 304 (also known as 1.4301) being the most common. It contains approximately 18% chromium and 8% nickel. Nickel is a particularly important element from the perspective of non-ferrous scrap metal — it is largely responsible for the value of stainless steel scrap on commodity exchanges.
What Makes Acid-Resistant Steel Different?
Acid-resistant steel is a subset of stainless steels that has been optimised for use in chemically aggressive environments — in contact with acids, seawater, chlorides, and other highly corrosive substances. The key distinguishing feature is the addition of molybdenum, typically in quantities of 2–3%. The most recognisable grade is 316 (1.4401) and its low-carbon variant 316L (1.4404).
Molybdenum enhances resistance to so-called pitting and crevice corrosion, making this steel indispensable in the chemical, pharmaceutical, food processing, and shipbuilding industries, as well as anywhere the material is in direct contact with aggressive media. Reactors, heat exchangers, industrial pipelines, and acid tanks are typical sources of this type of scrap at yards serving business customers and industrial facilities.
Chemical Composition and Scrap Prices — A Relationship Worth Understanding
At scrap yards dealing in non-ferrous and special metals, the price of stainless and acid-resistant steel is determined based on current nickel and molybdenum quotations on the London Metal Exchange (LME). This means rates can change from week to week, and the price difference between grade 304 and grade 316 can be substantial.
- Grade 304 — contains approx. 8% nickel, no molybdenum. The most commonly seen at scrap yards, priced according to the current nickel price.
- Grade 316/316L — contains approx. 10–14% nickel and approx. 2–3% molybdenum. The higher content of valuable elements translates into a higher scrap purchase price.
- Ferritic grades (e.g. 430) — contain chromium but virtually no nickel. They react to a magnet and are priced significantly lower than austenitic grades.
- Martensitic grades (e.g. 410) — hard, magnetic, used for knives and tools. Also lower nickel content, lower scrap price.
This is precisely why at a well-equipped scrap yard, staff use XRF analysers (X-ray fluorescence), which can read the elemental composition of an alloy within seconds — without damaging the material. This is the only reliable method for distinguishing stainless steel grades at the point of purchase, as the naked eye or a magnet alone are not sufficient when dealing with austenitic steels.
The Simple Magnet Test — Useful, But Not Enough
It is often said that a magnet helps distinguish stainless steel from ordinary steel. This is partially true. Austenitic stainless steels (304, 316) do not attract magnets, or do so very weakly. Ferritic and martensitic grades do. The problem is that a magnet cannot distinguish grade 304 from 316 — and it is precisely that difference which determines the higher price of acid-resistant scrap. Accurate identification requires compositional analysis, which is why professional measuring equipment at the scrap yard is so important.
How to Prepare Stainless Steel Scrap for Sale?
A few practical tips to help you get a better price and speed up the process:
- If you have technical documentation for the equipment or markings on the scrapped components (e.g. nameplates indicating the grade), bring them with you — this will make valuation easier.
- Visually separate items that differ in appearance, thickness, or hardness — they may be different grades.
- Remove components made from other materials (rubber seals, plastic connectors, bolts from different steel) where possible — contaminants reduce the scrap price.
- For larger quantities of industrial scrap, it is worth contacting the scrap yard by phone in advance to arrange a collection or delivery date and terms.
Where to Sell Stainless and Acid-Resistant Steel in Greater Poland?
EURO-SCRAP operates scrap purchasing points for non-ferrous metals, steel scrap, and special alloys at several locations in Poznań and the Greater Poland region. Weighing is carried out on certified scales, and every transaction is documented in accordance with applicable regulations, including BDO waste records for business customers. If you run a company and are disposing of industrial scrap, you will receive a complete waste acceptance document.
Customers from the Poznań area are welcome at our scrap yard Poznań Górczyn and Grunwald and at the scrap yard Poznań Jeżyce and Ogrody location. We also serve customers from outside the city — we operate, among other places, at scrap yard Przeźmierowo and Baranowo and at scrap yard Rawicz.
Summary — What to Remember Before Visiting the Scrap Yard
Distinguishing stainless steel from acid-resistant steel has a real impact on money. Grade 316 with its molybdenum addition is valued higher than the common 304, while ferritic steels without nickel are valued even lower. If you are unsure what you have, the scrap yard staff will identify the material on the spot. However, it is worth knowing where the material came from and whether it has any markings — such information speeds up the valuation process and helps you get the best possible price for the scrap you deliver.
