Difference between 304 Grade and 316 Grade Stainless Steel

304 Grade and 316 Grade Stainless Steel 

When dealing with stainless steel materials, people often have a tough time differentiating between “304 grade stainless steel” and “316 grade stainless steel”. The lack of understanding that persists can be justified given the fact that on the surface, the two grades of stainless steel in question look extremely similar, if not identical. They are virtually polished, grained and finished in the exact same fashion. Therefore, unless you are an expert on stainless steel or metallurgy in general, it would be very hard for you to pick up the tiny clues that tell us why these two stainless steel grades are different from one another.

Difference in Composition

The only way in which you can deduce the differences between the two grades is by conducting a proper material test report or MTR. Once the results of this test materialize, you will notice that it is in the composition or the material make-up of the two stainless steel grades where the major difference lies. In simple words, 304 contains 18% chromium and 8% nickel whereas 316 16% chromium content, 10% nickel content and 2% molybdenum. Although the changes in the concentrations of the various constituent elements do not appear that massive, they do however lead to significant changes in the characteristics of the two stainless steel grades. Alterations in the characteristic changes the applications for which the stainless steel grades may be purposeful.

Molybdenum Boosts Corrosion Resistance

The main difference between the two grades stems from the addition of the molybdenum in stainless steel grade 316. The presence of the molybdenum raises the corrosion resistance of the stainless steel, especially against chlorides (which are abundant underwater). As a result of that, grade 316 stainless steel naturally becomes more suitable for usage in conditions that do not favour the corrosion resistance of grade 304.

Higher Corrosion and Heat Resistance

Although grade 304 is arguably the most versatile stainless steel in the world today and is the most widely used austenitic stainless steel, it does not pack the same punch as grade 316 when it comes to providing heat resistance and incredible corrosion resistance. Grade 316, unlike grade 304, can be placed in highly corrosive solutions such as sulphuric acid, bromides and iodides without sustaining any significant damage. It’s ability to endure such hostile chemical solutions makes it the perfect fit for use in a number of different heavy duty applications such as in pharmaceutical activities and medical environments where replacing items from time to time is certainly not an option.

Which One is the Best?

At the end of the day, if you try to compare the two stainless steel grades and make your mind up on which of the two is better, then you will probably not come to a reasonable conclusion. This is because both the stainless steel grades have their own merits, and should be judged on the basis of their uses, the number of which is plenty for both. It is up to the purchases of the stainless steel grade to decide which type best suits the requirements of his or her applications.

Cougartron ProPlus for Stainless Steels

Talking of stainless steel, did you know that the Cougartron ProPlus is perfect for stainless steel maintenance? The ProPlus is designed to give you the most efficient, the fastest and the safest stainless steel maintenance in the world. Whether it be cleaning, polishing or etching, Cougarton ProPlus is the ultimate device that provides you with a top notch service. It’s easy to use, lasts for a long time and is far more effective than any other system out there. Not to mention, its intelligent electronics allows it to provide consistent power and uninterrupted production.

12th October 2017

Can we determine which one is SS 304 or 316 material just using a magnet object ?

16th October 2017

This can only be reliably differentiated by chemical analysis or some similar technique. You can try the magnet test. If the magnet sticks it cannot be 316 and might be 304. If the magnet doesn’t stick it could be either 316 or cold worked 304, so heat the piece to about 800 °C, let air-cool and try again with magnet. If it sticks now its 304. Heavy cold working results in a small attraction of 304 to a magnet, while cold worked 316 is only faintly attracted. Annealing removes the magnetism, so if annealed stainless sticks to a magnet, it’s a ferritic, martensitic or duplex SS.

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