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Unveiling the Mystery: What is Stainless Steel? A Comprehensive Guide to Identifying Common Types

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

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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 the steel 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.

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 an 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 conditions 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, 316, followed by ferritic grades such as 430, 410, and duplex 201.

Comparing Common Inox Types

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

Inox 304

Widely used globally, this type contains up to 10.5% nickel and 20% chromium. Its exceptional properties make it a top choice for various applications.

Inox 201

Popular due to its affordability and suitability for many applications. It has reduced nickel content (7.1%) replaced by manganese. While its corrosion resistance is lower than other types, its cost-effectiveness makes it a common choice.

Inox 316

Offers the best corrosion resistance due to its molybdenum content, making it ideal for environments with corrosive salts like chlorides and fluorides.

Inox 430

Contains at least 18% chromium and no nickel, making it the least durable among the 4 common types, 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, if the surface turns yellow, it’s inox 201 or 430. 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, mild attraction indicates inox 201, and no attraction indicates inox 316. Slight attraction indicates inox 304.

Note: Avoid using magnets on finished inox products, as they may have acquired magnetism during processing.

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. Its key feature is high corrosion resistance. For kitchen products, SUS304 (18Cr-8Ni) is commonly used.

What is Inox and Its Applications in Manufacturing?

Inox is a stainless steel alloy with at least 10.5% chromium, resistant to corrosion and environmental factors. It’s 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 are the Common Inox Forms in Mechanical Engineering?

Inox comes in round pipes, square pipes, solid bars, sheets, and various shapes for mechanical engineering applications.

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 Suitable for Marine Environments?

Yes, inox is highly resistant to seawater corrosion and is used in ships and coastal 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 the 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 Drawbacks?

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

Is Inox Used in Aerospace?

Yes, inox is used in aircraft and spacecraft 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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