Austenitic SS 304

Austenitic SS 304

Here’s a breakdown of the components and properties of Stainless Steel 304.

Multi-purpose stainless steel consists of iron-based alloys, and the name (stainless steel 304) refers to its ability to resist varied types of corrosion. This resisting property is due to the interaction between its alloying components and the environment, where the exposure takes place. Ever popular, the 304 stainless steel (or SS 304) is durable and widely used, making it austenitic steel available in numerous forms and finishes.

This austenitic steel is a Chromium-Nickel austenitic stainless steel alloy. Stainless steel is an alloy, and the 304 SS composition is 18% Chromium and 8% Nickel, coining the 18/8 stainless steel name. Due to the austenitic structure, the material in SS 304 is ductile in nature.

Comparing the SS 304 to carbon steel, the former is less electrically conductive and essentially non-magnetic. It has a higher corrosion resistance than regular steel, and in addition to that, it can be used with ease, thus creating multiple formats and shapes.

That’s not all! The 304 stainless steel properties are not specific to a domain, but diverse too. One noteworthy characteristic of SS 304 is the excellent corrosion resistance to a wide range of atmospheric conditions, which often cause corrosive effects. SS 304 is subject to pitting and crevice corrosion in environments of warm chloride and also to stress corrosion cracking in temperatures above about 60°C. The 304 stainless steel properties are impressive – from forming and welding properties, to corrosion and oxidation resistance. This is because of the element chromium, known for its toughness, even deep down to cryogenic temperatures.

The carbon content in the 304 grade stainless steel strengthens and prevents the alloy from fragility. The SS 304 grade has brilliant processing capabilities, and the cold working technique occurring at low-temperature results in a positive response, obtaining a hardened final product.

All these properties further the SS 304’s use in manufacturing processes and applications. 304 stainless steel is not only a boon to the industrial sector but also a household saviour. It can be found in food handling and processing equipment, screws, machinery parts, and car headers. The 304 stainless steel is utilized in the architecture for exterior accents such as water and fire features.

The 304 grade stainless steel is available in two different forms, namely 304H and 304L stainless steels. They all possess the same nominal amounts of chromium and nickel, which enable the same corrosion resistance, ease of fabrication and weldability.

The carbon content of 304H (UNS S30409) is restricted to 0.04% – 0.10%, which provides optimal high temperature strength. The carbon content of 304L stainless steel (UNS 30403) is restricted to a maximum of 0.03%, which prevents sensitization during welding. Sensitization is the formation of chromium carbides along grain

boundaries when stainless steel is exposed to temperatures in the range of ~900 °F (480 °C) – 1,500 °F (820 °C).

In the case of type 304L stainless steel is the real deal. It is the most common type among stainless steels found across the globe because of its nature of easy processing and immediate availability. The magical trait of this 304L is because of its 0.035% carbon content, making it very ductile, stretching into thin wire, and even hammering it without breaking.

Type 304H has a higher carbon content (about 0.04% – 0.10%), which helps in making it a grade with diverse applications at any given elevated temperature. Both these grades, 304L and 304H, do not require any additional filler material because of its machinability and weldability. They possess a combination of low yield strength and high elongation, and can easily change into different shapes, however complex.