904L vs. 304L

904L vs. 304L Stainless Steel: Key Differences, Applications, and Equivalents

 

904L Stainless Steel .pdf

 

Choosing the right stainless steel grade is critical for balancing corrosion resistance, mechanical performance, and cost. Among the many options, 304L and 904L stainless steels are commonly discussed-especially when durability in corrosive environments is a concern. This article compares 904L vs. 304L and answers key questions about their composition, applications, and global equivalents.

 What Is the Difference Between 304L and 904L Stainless Steel?

Property	304L Stainless Steel	904L Stainless Steel
UNS Designation	S30403	N08904
EN Standard	1.4307	1.4539
Nickel Content	~8–10.5%	~23–25%
Molybdenum Content	None	~4–5%
Corrosion Resistance	Good in mild environments	Excellent in highly corrosive environments
Cost	Low	High

904L is a super austenitic stainless steel with superior resistance to chlorides, sulfuric acid, and aggressive chemicals, while 304L is a cost-effective general-purpose grade suitable for mild corrosive environments like kitchens or architectural applications.

What Does the "L" in 304L Stand For?

The "L" in 304L stands for "Low carbon."
It means the carbon content is reduced to 0.03% max, which improves weldability and reduces the risk of intergranular corrosion after welding. The same applies to 904L, which also has low carbon content for similar benefits.

What Is 904 Stainless Steel Used For?

Despite being more expensive, 904L stainless steel is used in demanding chemical and marine environments, including:

Chemical processing plants

Acetic and sulfuric acid handling

Seawater piping systems

Heat exchangers and condensers

Luxury watches (due to its high corrosion and aesthetic properties)

Its high nickel and molybdenum content makes it ideal for extreme environments where 304L and even 316L may fail.

What Is the Equivalent of Stainless Steel 304L?

UNS S30403

EN 1.4307

JIS SUS304L

ASTM A240 / A312 (plate/pipe standard)