The existence of these stainless steel variants can cause some confusion—especially when the names & formulations of two stainless steel alloys are almost the same. This is the case with grade 304 and 304L stainless steels.
304 and 304L stainless steels are among the most versatile and widely used of all the stainless steel grades. So, what’s the difference between the two stainless steel?
Benefits of 304 and 304L Stainless Steel
High strength Excellent Formability and Weldability Excellent Low-Temperature Properties Great Response to Hardening by Cold Working High Corrosion/Oxidation Resistance Carefully Controlled Chemical Composition Affordable Cost
304 and 304L can be press-baked or roll-formed into numerous shapes for various applications across industrial, architectural and transportation sectors.
What is the Difference Between 304 and 304L Stainless Steel?
The Mechanical Difference
Grade 304L has a slight, but noticeable, reduction in key mechanical performance characteristics compared to the “standard” grade 304 stainless steel alloy.
The Corrosion Difference
When it comes to variations between 304 and 304L stainless steel, an essential thing to note is the latter’s greater immunity to intergranular corrosion. Intergranular corrosion is the cracking that can occur along grain boundaries of steel in the presence of tensile stress.
304 stainless steel has good welding characteristics and does not typically require post-weld annealing.
304L stainless steel also doesn’t require post-weld annealing and is widely used in heavy-gauge components where its immunity to carbide precipitation is needed.
Why Would You Want to Use 304L, Then?
So, if 304L is weaker than standard 304 stainless steel, why would anyone want to use it?
The answer is that the 304L alloy’s lower carbon content helps minimize/eliminate carbide precipitation during the welding process. This allows 304L stainless steel to be used in the “as-welded” state, even in severe corrosive environments.
If you were to use standard 304 stainless in the same way, it would degrade much faster at the weld joints.
Basically, using 304L eliminates the need to anneal weld joints prior to using the completed metal form—saving time and effort.
In practice, both 304 and 304L can be used for many of the same applications. The differences are often minor enough that one isn’t considered massively more useful over the other. When stronger corrosion resistance is needed, other alloys, such as grade 316 stainless steel, are usually considered as an alternative.
Common Applications of 304 and 304L Stainless Steel
Precision Engineering Precision Parts Precision Turning Custom Machined Parts Chemical Processing Equipment Textile Industry Equipment Paper Industry Processing Equipment Pharmaceutical Equipment Architectural Moldings Kitchen Equipment