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What is Stainless Steel? A Comprehensive Guide to Identifying Common Types of Stainless Steel

Stainless steel, a versatile and familiar material, is widely used in the production of various essential items, offering durability and a sleek finish that meets both functional and aesthetic demands.

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25 September, 2025

Stainless Steel, commonly known as inox, is an alloy composed of metals such as Nickel, Chromium, Copper, Iron, Carbon, Manganese, Silicon, and more. This material stands out for its high durability, resistance to corrosion, and color retention, making it widely used in various everyday products.

The durability of inox depends on the mixture of metals like Chromium and Carbon. Inox exhibits excellent oxidation resistance when it contains a high percentage of Chromium. Currently, the most common types of inox are 201, 410, 304, 301, and 430.

Properties of Inox

Inox properties are categorized into 4 main groups, each with several subtypes:

Austenitic: SUS 301, 304, 304L, 316, 316L, 321, 310s, etc.
Ferritic: SUS 409, 410, 430, etc.
Austenitic-Ferritic (Duplex): LDX 2101, SAF 2304, 2205, 253MA, etc.
Martensitic: 420S45, 248SV, etc.

General properties of inox include:

Alloy Group	Magnetic	Corrosion Resistance	Ductility	Heat Resistance
Austenit	No	High	Very High	Very High
Duplex	Yes	Very High	Medium	Low
Ferritic	Yes	Medium	Medium	High
Martensitic	Yes	Medium	Low	Low
Precipitation Hardening	Yes	Medium	Medium	Low

Inox has 4 main property groups with various subtypes

Common Types of Inox

Inox (stainless steel) is a form of iron alloy containing at least 10.5% Chromium. It is highly resistant to discoloration and corrosion compared to regular steel. Its ability to withstand harsh environments, high humidity, and outdoor weather makes it an excellent material for various manufacturing fields.

Currently, there are hundreds of inox types, categorized into 4 main groups: austenitic, ferritic, duplex, and martensitic. The most common type is austenitic, with grades like SUS 201, 304, and 316. Ferritic grades such as 430, 410, and duplex 201 are also widely used.

Comparing Common Inox Types

Let’s compare the 4 most common inox types: 304, 316, 201, and 430.

Inox 304

Widely used globally, inox 304 contains up to 10.5% nickel and approximately 20% chromium. These properties make it highly versatile and meet user demands effectively.

Inox 201

The most commonly used type today due to its suitable quality and size. Its nickel content is reduced, replaced by 7.1% manganese. Inox 201 has lower corrosion resistance compared to other types but is more affordable.

Inox 316

Offers the best corrosion resistance due to its molybdenum content, which is absent in other common inox types. It excels in environments with corrosive salts like chlorides and fluorides.

Inox 430

Inox 430 contains at least 18% chromium and no nickel, making it the lowest quality among the 4 common types. It is prone to corrosion and discoloration.

How to Distinguish Common Inox Types

Using Acid

A common and accurate method. Prepare inox 201 and 304 samples and a small amount of acid. Drop acid onto both samples and observe for 10 seconds.

If the sample bubbles and turns brick red, it’s inox 201. If there’s no reaction and the acid spot remains gray, it’s inox 304.

Using Specialized Test Kits

Clean the inox surface, then apply a drop of the test solution. Wait 3 minutes and compare the color change to the chart on the packaging. Darker colors indicate lower quality.

If the solution turns red but doesn’t fade within 5 seconds, it’s inox 316. If it turns red and fades immediately, it’s inox 304. Black or no color change indicates inox 201 or 430. Use a magnet to differentiate between 201 and 430.

Using Toilet Bowl Cleaner

Scratch the inox surface, then apply toilet bowl cleaner. After 20 minutes, yellowing indicates inox 201 or 430, while no change indicates inox 304 or 316. Use other methods to differentiate further.

Using a Magnet

Place a magnet near the inox samples. Strong attraction indicates inox 430, moderate attraction indicates inox 201, weak or no attraction indicates inox 304, and no attraction indicates inox 316.

Note: Avoid using magnets on finished inox products, as processing can induce magnetism, making this method unreliable.

Frequently Asked Questions About Inox

What is Stainless Steel?

Stainless steel (inox) is an alloy made from iron (Fe) and chromium (Cr), containing 1.2% carbon (C) or less. It is known for its high corrosion resistance. SUS304 (18Cr-8Ni) is commonly used in kitchen products.

What is Inox and Its Applications in Manufacturing?

Inox is a stainless steel alloy containing at least 10.5% chromium, resistant to corrosion and environmental factors. It is used in household items, medical equipment, food industry, and more.

Why Doesn’t Inox Rust?

Inox resists rust due to chromium forming an oxide layer on the surface, protecting the inner iron from corrosion.

How is Inox Processed?

Inox can be cut, ground, bent, welded, and polished into finished products.

What are the Main Inox Products in Manufacturing?

Inox is used to produce pipes, sheets, bars, wires, and household items like showerheads and sinks.

How to Polish Inox for a Shiny Surface?

A shiny inox surface is achieved through polishing and chromium plating.

Can Inox Withstand High Temperatures?

Yes, inox is used in chemical and metallurgical industries due to its heat resistance.

How is Inox Used in the Food Industry?

Inox is used for food storage equipment, cooking vessels, and water pipes due to its safety and durability.

Is Inox Highly Durable?

Yes, inox is highly durable, corrosion-resistant, and chemical-resistant, ensuring long-term structural integrity.

How to Clean and Maintain Inox Products?

Clean inox with warm water and soap. Store in a dry place, avoiding corrosive chemicals.

What Shapes Can Inox Take in Mechanical Engineering?

Inox can be shaped into round pipes, square pipes, solid bars, sheets, and more, depending on the application.

Why is Inox Ideal for Medical Products?

Inox is corrosion-resistant, easy to clean, and ideal for medical tools and equipment.

How to Weld Inox?

Use TIG or MIG welding to avoid surface rust.

Is Inox Durable in Seawater?

Yes, inox is highly resistant to seawater corrosion and is used in marine structures.

Why is Inox Called “Inox”?

“Inox” comes from the French “inoxydable,” meaning non-oxidizing, reflecting its corrosion resistance.

Can Inox Be Recycled?

Yes, inox can be recycled and reused for new products.

What are Common Inox Alloys?

SUS 304 and SUS 316 are popular, with chromium and nickel as main components.

Is Inox Used in Renewable Energy?

Yes, inox is used in solar and wind energy systems.

What are Inox’s Disadvantages?

Inox is more expensive than other steels and requires specialized processing.

Is Inox Used in Aerospace?

Yes, inox is used in aircraft and spacecraft components due to its durability and heat resistance.

What Makes Inox Unique in Manufacturing?

Inox stands out for its corrosion resistance, chemical resistance, and aesthetic appeal, making it ideal for various applications.

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