As the name implies, stainless steel is highly resistant to staining. It comes in many types; this article describes the types of “304 and 303 stainless steel”; these are the most commonly used forms of stainless steel for bushings, bolts, nuts etc.
These two types belong to the ferritic metal family. Ferritic stainless steels usually contain high levels of nickel and chromium and are non-magnetic. What distinguishes them from other metals and series is their corrosion resistance and formability.
Both 303 stainless steel and 304 stainless steel are made of iron. 303 stainless steel and 304 stainless steel have almost identical formulations.
But what are the differences between 303 and 304 and how do you decide which one to choose? In this article you will find the answers you are looking for, of course in relation to stainless steels 304 and 303.
What is 303 stainless steel?
Compared to other types of austenitic stainless steel, Type 303 performs best in terms of machinability. It is mainly used in the manufacture of automatic screw machines that incorporate large mechanical processes. Its machinability index (compared to B1212) is approximately 78%.
303 is available as the “ultimate” enhanced machinability grade. Has a higher machinability than standard 303.
What makes 303 less resistant to corrosion than 304 is the addition of sulphur. It is responsible for improving the excisability and machinability characteristics of Grade 303. It is this structure that gives 303 its excellent toughness compared to other austenitic grades, although the sulphur in 303 reduces its toughness to some extent.
Grade 303Se (UNS S30323) has no added sulphur, but has added selenium, which gives it greater hot and cold build-up characteristics and a smoother machined surface than 303. The machinability index is smoothly reduced. 303Se grade is not available in Australia.
What is 304 stainless steel?
Grade 304 is an “18” class stainless steel. It is the most widely used and flexible stainless steel available, although there are a considerable number of alternatives; and it has excellent welding and forming properties.
The uniform shape of Grade 304 austenite allows it to be drawn tight without the need for intermediate annealing. This means that this grade of steel dominates in the creation of stretched stainless steel components such as frying pans, pots and sinks. In particular, the “304DDQ” variant is commonly used for these applications.
Grade 304 can be easily ground or rolled into various elements for use in construction, transport and industrial applications. It also has excellent welding properties. When welding thin sections, no post-weld annealing is necessary.
Grade 304L, a low carbon version of 304, does not require pre-weld annealing and is therefore widely used for large gauge parts (over 6 mm). Due to its higher carbon content, grade 304H has been used for high temperature applications. In addition, the austenitic form provides exceptional toughness at these levels. The austenitic structure also gives these grades excellent toughness, even at low temperatures, even at very low temperatures.
303 vs 304 stainless steel, what is the difference?
303 is always used in situations where smooth cutting and extreme surface finishes are mainly required. It contains selenium and so cuts easily, whereas 304 is a flexible stainless steel and does not contain selenium. It is often used to produce high performance (formability and corrosion resistance) materials and machine parts.
We will discuss in detail the differences between 303 and 304 in 4 areas: alloy composition, mechanical properties, applications for beginners and cost.
Alloy comparison
The table shows the typical composition range of 303 and 304 grade stainless steel sheets.
| Element | 303 Stainless steel plate | 304 Stainless steel plate |
| C | Max 0.15 | Max 0.08 |
| Cr | 17.0~ 19.0 | 18.0 ~20.0 |
| Se | / | min 17.0 |
| Mn | Max 2.0 | Max 2.0 |
| Si | Max 1.0 | Max 0.75 |
| P | Max 0.2 | Max 0.045 |
| S | min 0.15 | Max 0.03 |
| Ni | 8.0 ~10.0 | 8.0 ~10.5 |
| N | min 0.1 | Max 0.1 |
| Fe | Balance | Balance |
Application Comparison
Users consider 304 stainless steel to be food grade because it is mainly used for packaging equipment. Others consider 304 stainless steel sheet for general use, so let’s take a look at the actual applications.
Grade 303 stainless steel is generally used for items that require heavy-duty machining and is ideal for small, complex parts. Conventional applications include.
-Aircraft gears and fittings
-Bushings
-Electrical components
-Screws, bolts and nuts
-Shafts
Grade 304 stainless steel, due to its aesthetic appeal and superior corrosion resistance, is typically found in the following applications
-Aerospace components
-Construction components
-Threading
-Packaging
-Food processing
-Automotive parts
-Chemical containers
-Heat exchangers
-Construction materials
-Liquid or food processing equipment
-Kitchen appliances, utensils and surfaces
-Cost components
Costs can climb quickly, depending on project requirements and the form of property you are looking for. It is customary to spend a little more on 303 stainless steel than type 304; however, costs still change periodically as the market changes.
The best way to deal with these changes is to deal with OEM merchants who can help you decide if your particular project requires a more expensive alloy.
F&A&Q
Here are some of the most common questions you may encounter when thinking about the differences between the two grades of stainless steel, 303 stainless steel and 304 stainless steel. Follow up.
Abstract
Through this article, I believe you have a certain understanding of the difference between 303 stainless steel and 304 stainless steel, if this article is helpful to you, please share it with more people, it’s my pleasure, thank you!
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