What is the difference between 302 and 304 stainless steel?

Stainless steels are one of the most common types of materials used in construction because they are austenitic and non-magnetic. As both of them contain chromium and nickel in their composition, they have properties that make them corrosion-resistant and have high strength properties. As you can see from the composition of the 302 material, it contains 0.15% carbon, 17% minimum chromium, and 8% minimum nickel. 304 steel is composed of 0.08% carbon, 19% minimum chromium, and 8% minimum nickel with a minimum carbon content of 0.08%. 304 material has a higher content of chromium than 302 material, which gives it a bit of an advantage over 302 material in terms of corrosion resistance.

The strength values of the 302 material, on the other hand, are higher than those of the 304 material. A 304 steel material can withstand a minimum tensile strength of 515 MPa, whereas a 302 steel material can withstand a minimum tensile strength of 585 MPa. In addition, the yield strength of 302 is 240MPa, whereas that of 304 is only 205MPa. The elongation at break for 302 is higher than that of 304 as well. In comparison with the 304 material, the 302 has a higher carbon content, which makes the material more durable in comparison to the 304. As compared to the 302, the 304 is much more ductile 302, because the 302 is more robust and stronger.

A stainless steel alloy 302 is also an austenitic stainless steel alloy, just like grade 304. Due to the fact that they share certain elements, it is what gives them the same austenite microstructure that gives them their similar appearance. As a result of the modification of the composition of the elements, they, however, fall into different grades purely as a result of their difference in composition. In grade 302, for instance, the maximum amount of carbon can be found at a maximum of 0.15%, whereas the maximum amount of carbon can be found at a maximum of 0.8% in stainless steel alloy 304. 304 austenitic steel is known for its lower carbon content than grade 300 austenitic steel, which also reduces the risk of carbide precipitation, which occurs when alloys have a higher carbon content than grade 300 austenitic steel. It is important to mention that one of the main benefits of using grade 302 stainless steel alloy is that it exhibits good resistance to solvents, and acids, as well as resisting a number of chemicals.

302 Stainless Steel

As a result, 302 is often used in applications where corrosion resistance is important, such as marine environments, where corrosion resistance is essential. Additionally, it is often used in food processing applications, due to the fact that it will not leach harmful chemicals into the food. As a result of its high carbon content, 302 is not suitable for applications where high temperatures are a concern, due to its high carbon content.

304 Stainless Steel

On the other hand, 304 is an alloy that is often used in high-temperature applications due to its low carbon content. This means that 304 is less likely to suffer from heat damage than 302, which means that 304 is more heat resistant. In addition, due to the low carbon content of 304, it is not necessary to heat-treat the steel after welding – unlike 302, which requires heat-treating in order to prevent sensitization.

The price difference between 302 and 304

In terms of price, both the 304 and 302 materials are priced similarly, but there is a slight difference in the prices of the two materials. The 302 material, even when it has a lower cost, is difficult to machine and form due to its harder texture compared to the 304 material. Because of this, the 304 material is used in applications where the 302 material is used only if the 304 is not needed, and when heavy welding or machining is not required.

Austenitic stainless steel grade 302 is basically the same as austenitic stainless steel grade 304 in terms of its chemical composition. Despite the fact that they have the same chemistry, the only difference is that grade 304 has a higher carbon content, which gives it a higher hardness. Therefore, it can also be assumed that the alloying cost for both stainless steels would be roughly the same or within a similar range.

302 and 304 stainless steel welding

There are a number of conventional welding processes that can be used to weld stainless steel grade 304. An anneal is necessary once this alloy has been welded. After the weld has been completed, a post-weld annealing treatment can be performed to assist in restoring the corrosion-resistant properties of the material. Generally, welding without an annealing treatment can lead to a loss of corrosion resistance properties by causing sensitization to intergranular corrosion, leading to a reduction in corrosion resistance properties. During this stage, chromium carbide precipitates will form between grains, causing corrosion to occur in the weld HAZ or heat-affected zone, which causes chromium carbide precipitates to be formed within the grain boundaries. However, the chances of intergranular corrosion are greatly reduced since the carbon content is less than grade 302, which means there is a lower chance of corrosion between grains. In addition to shielded fusion welding and resistance welding processes, 302 stainless steel can also be readily welded using techniques such as fusion welding. We are not allowed to use Oxyacetylene when welding, simply because of the potential for carbon pick-up during the welding process. There are a number of filler metals that are required when working with this alloy. Depending on the welding process, either AWS E/ER308 or 312 may be used as filler metals during the welding process. Similarly, for grade 304, a post-weld annealing process is required to be conducted in order to ensure the quality of the product. Due to the presence of chromium carbide, this treatment is required, particularly since it is necessary to dissolve the existing chromium carbide. In order for the alloy to be resistant to intergranular attack at its greatest potential, the chromium carbide must be dissolving from it.

The carbon content in the 302 material is higher than the carbon content in the 304 material. Neither of these materials requires any preheating or post-weld heat treatment prior to welding, but they both have the possibility of precipitating chromium carbide during the welding process. Since the 304 material has a low carbon content, it is easier to weld and causes a smaller amount of precipitation of chromium carbide, as well as intergranular corrosion, compared to the 302. In the welding procedure of the 302 material, more chromium carbide precipitates due to the presence of chromium carbide, making it much more prone to intergranular corrosion and a decrease in strength at the joints where it is welded.

302 and 304 stainless steel melting point

There is no fixed melting point for most alloys, but both of these austenitic stainless steels are among those that have a melting range. An alloy is made up of a combination of several elements or metals, all of which have different melting points since they are an assembly of several elements or metals. As for alloys, a melting point, or what is also known as a melting range, refers to a temperature at which the solid metal becomes liquid, forming a sludge as a result of the processes involved. 304 and 302 have generally similar chemistry, and their melting points are compatible since their chemistry is the same for both grades. The melting point of stainless steel 302 varies between 2550°F and 2590°F during the process of melting, and the melting point of austenitic stainless steel 304 varies between 2,550°F and 2,650°F during the processing.

Its material has a high melting point of 1450 degrees Celsius as a result of its low carbon content and high nickel content. In comparison to the 302 material, the melting point of the 302 material is lower at 1421 degrees Celsius. Due to the difference in melting point, the operating temperature range is affected by the melting point difference. In a logical sense, the 304 material should be able to withstand higher temperatures than the 302 material. For the 304 material, there is a wide range of operating temperatures ranging from 650 degrees Celsius up to 870 degrees Celsius, while the 302 material, works better at lower temperatures.

The 302 material can be used in applications that require high strength, low corrosion, and low temperatures without any problem, as it is able to meet the requirements. There are situations where the 302 material cannot handle corrosive conditions, and the required operating temperature is higher than the 302 material, in which case the 304 material is preferred. Both these materials have applications in oil and gas, general corrosion, as well as construction.

Durability

In general, stainless steel is very corrosion-resistant because of its natural properties. It is important to note that grade 303, in contrast to grade 304, has a composition that has been modified to make it more machinable, which results in weakened corrosion resistance. Stainless steels of type 304 have been proven to be extremely tough and corrosion-resistant, however, they can be subject to pitting in environmental conditions such as those involving warm chloride-based environments.

Applications

The 302 stainless steel is designed for general-purpose industrial applications and is designed to offer a greater degree of corrosion resistance than the 301 stainless steel. In order to reduce the possibility of carbide precipitation in stainless steel, 304 stainless steel is constructed with a lower carbon percentage. It is commonly used in applications where high temperatures are involved in the use of stainless steel.

302 vs 304 Stainless Steel – What’s the Difference

Chemical composition

The chemical composition of stainless steel is one of the main differences between 302 stainless steel and 304 stainless steel. In comparison to 304 stainless steel, 302 stainless steel contains a higher percentage of chromium and nickel, making it ideal for applications that require corrosion-resistant stainless steel. Furthermore, due to the lower amount of chromium and nickel in 302 stainless steel, it is slightly less durable than 304 stainless steel.

Tensile strength

The tensile strength of stainless steel 302 and 304 is another difference between them. Stainless steel 302 has a higher content of chromium and nickel than stainless steel 304, which gives it a higher tensile strength than stainless steel 304, making it an ideal material for applications that require high levels of strength.

Temperature resistance

The temperature resistance of stainless steel 302 and 304 is also different. A stainless steel 302 is more suitable for applications that require high temperatures, since it has a higher melting point than a stainless steel 304, so it is more suitable for high temperature applications. However, 304 stainless steel is more resistant to corrosion than 302 stainless steel, making it the better choice if corrosion resistance is required in the application.