Stainless steel is a property notorious for its corrosion resistance and remarkable ability to resist stains. That said, stainless steel is broken down into different grades, each with slightly varying characteristics based on the chemical makeup. Below, we review the differences between grades 303 vs 304 stainless steel.
Grade 303 stainless steel is similar to grade 304 stainless, but with sulfur added to help increase machinability while maintaining both corrosion resistance and mechanical elements that are associated with stainless steel. The added sulfur decreases corrosion resistance of grade 303 when compared to grade 304, but for certain applications the machinability is worth the trade-off.
Grade 304 stainless is among the most popular alloys due to its incredible corrosion resistant properties. Its low carbon content makes it ideal for welding operations common to the construction industry, among others. Type 304 stainless is austenitic and non-magnetic, meaning it also provides low thermal and electrical conductivity.
Deciding whether to use grade 303 vs 304 stainless steel often comes down to determining what the application will be. There are several factors that come into play when choosing the type of stainless steel to use.
Stainless steel in general is naturally corrosion resistant. However, type 303 has a composition that’s been altered to increase machinability, so it’s weakened to corrosion resistance compared with grade 304. Type 304 stainless steel boasts incredible toughness and corrosion resistance but is susceptible to pitting in situations such as warm chloride-based environments.
Machinability, heat treatment, weldability – these are all important factors in the type of stainless steel you use for your application.
Type 303 stainless is a free-cutting material, with the best machinability of any austenitic stainless steel. That said, grade 303 steel is, for the most part, unweldable. Type 304 stainless doesn’t harden with heat treatment and is not a free-cutting material, making it less than ideal for use in machining. However, grade 304 stainless steel is relatively weldable.
Grade 303 stainless is typically used for parts that need to be heavily machined, making it ideal for intricate, small components. Common applications include:
· Aircraft fittings and gears
· Electrical components
· Screws, nuts and bolts
Grade 304 stainless steel, due to its superior corrosion resistance and aesthetic, is more often found in applications such as:
· Aerospace components
· Architectural components
· Automotive parts
· Chemical containers
· Construction materials
· Food or liquid processing equipment
· Heat exchangers
· Kitchen appliances, surfaces and utensils