303 Stainless Steel – The Ultimate Guide

303 Stainless Steel

There is the need to know about 303 stainless steel, its various applications, properties, element compositions, and more before you finally decide.

This guide will help you know more about the 303 SS and how it is different from the others – let’s delve in.

What is 303 SS?

This alloy is also called 1.4305 or UNS S30300. When all austenitic grades of SS are mentioned, grade 303 is known to be very easy to use.

It’s machinable and usable nature is linked to the Sulphur presence in it.

 

303 Stainless Steel Properties

Most of the properties it has is similar to those of other grades of SS.

Mechanical Properties

Quite a number of variables can be used to gain clarity on mechanical properties and strength of 303 which includes:

  1. The best yield strength which is 0.2% and 450 – 650 Mpa
  2. Fine tensile strength stands at 750 – 800 Mpa
  3. 34% elongation at break which is about 50mm sheet.
  4. 95 Rockwell
  5. 262 Brinell

There is the need to note that, all the above values are not stagnant. Anytime you import 303 SS, ensure the manufacturer makes available to you detailed specifications of data connected to mechanical properties.

The data given will be dependent on their own tests.

Austenitic Stainless Steel
Austenitic Stainless Steel

Chemical 303 SS Properties

By the composition elements below as you read, nickel of 10% and chromium of 19% do their work in the following ways:

  1. Resists oxidation to perfection. Although 303 must not be widely exposed to some environments like marine environments, it provides the best oxidization resistance of up to 760oC.
  2. Best resistance to corrosion. Corrosion is resisted to its highest point even at working temperatures. However, it is not advisable to use within ranges 450oC to 860oC. This is due to carbide precipitation.
  3. Chemical resistance. It has resistance to sulphur.

Physical Properties of 303 SS

303 ss comes with a density of 7900 kg. It has an electrical conductivity or resistivity of about 720 nΩ.m. Also, at 0 to 100oC:

  • The coefficient of thermal expansion is 3 µm/moC
  • Conductivity is approximately 16.3 W/m.K.

303 Stainless Steel Equivalent

303 SS Sheet
303 SS Sheet

This grade of alloy is compared mostly with grade 304. This is due to the many similarities in features and elements they offer.

What makes them similar:

  1. Both 303 SS and 304 SS have about 17% Cr, and 8% Ni.
  2. They both come with unique machinable features.
  3. Corrosion resisting features are almost the same in 303 and 304.

Details of 303 Stainless Steel Composition Elements

Let’s look at the main element composition:

Element Minimum % Maximum %
Sulphur 0.15 0.35
Carbon 0 0.15
Nickel 8.00 10.00
Manganese 0 2.00
Chromium 17.00 19.00
Silicon 0 1.00
Phosphorus 0 0.06

Unique Differences of 303 and 304 Stainless Steel

304 SS has superior corrosion resistance. Additionally, grade 303 has sulphur and phosphorous. However, in some cases, machinability outweighs this advantage.

Your decision to use grade 303 or 304 SS will and should be based on the industry where you will be using it and also the end result expected.

Consider these disparities where 303 and 304 is concerned:

  1. Ease to use. Cutting 303 is very easy and comes with the finest machinability features more than 304.
  2. Welding. Welding 303 is not very easy. 304 on the other hand can be welded. However, it is not easy to cut and use like 303 is.
  3. Chemical composition. Grade 303 typically does have more carbon, silicon, phosphorus, and sulphur than grade 304, which in turn increases extra chromium.
  4. Pricing or cost. Choosing to buy and use 303 will cost you some more money compared to buying 304.

Comparing 303 SS vs 316 Stainless Steel

The low heat and electrical conductivity characteristics are a result of non-magnetic and austenitic nature of 303.

Besides, 316 stainless steel has molybdenum. Of course, this is alongside high amounts of nickel. As a result, 316 SS has unmatched corrosion resistance properties. Because of this, it works perfectly in any environment, including ones with chloride.

Considering the differences on these levels:

  1. Strength levels. 316 comes with better temperature, and tensile strengths compared to 303.
  2. Chemical structure. The chemical makeup is very necessary when comparing 303 and 316. Less chromium and nickel can be found in 303 compared to 316. That leads to a less or low outcome where corrosion resistance is concerned. Also, 303 SS is not as heat resistant as 316 is.
  3. Price or cost. The price is another consideration. In general, 303 stainless steel costs less than 316. Yet, the greater corrosion resistance and capacity to bear higher temperatures in 316 SS are what account for its higher costs.
  4. Uses. Both steels 303 and 316 are frequently utilized in a variety of applications. 303 is frequently used for electrical parts or components, architectural trim, and food processing equipment. Medical tools, maritime hardware, and equipment for chemical treatment are a few common uses for 316 SS.
  5. Welding features. Whereas 316 stainless steel requires the use of an approved process due to its high carbon content, 303 can be welded using any conventional welding procedure.
  6. Corrosion resist. One of 316’s main pros over 303 is its greater ability to resist corrosion. This exceptional resilience is because of the inclusion of molybdenum, which creates a barrier coating layer on the metallic surface to impede corrosion.

Designations of SS Grade 303 Alloy

Grade 303 works perfectly as well to these designations:

Euronorm UNS BS
1.4305 530300 303531

Estimating Current Stainless Steel Price

The price of steel is affected by the characteristics of steel and the place where it is bought. Demand determines how much steel costs at any time.

Considering the certain types of steel are tougher than some others, the final product’s level of workmanship also influences the cost of steel.

Steel is mostly calculated per ton with this equation SCPT = SC/(W/2000). Here:

  1. SCPT represents the steel cost per ton ($ or ton).
  2. SC represents the steel cost ($).
  3. W represents the weight of steel (lbs)

With the above stated, the fluctuation of currencies worldwide can also affect the cost of steel.

Fabricating 303 SS

The fabricating process helps in transforming 303 alloy into products that are beneficial for use in various industries.

So, before you decide on using this metal for your fabrications, getting to know its welding, heat treatment, and machining abilities is important.

303 SS Welding Properties

 

The presence of sulphur in 303 SS is what makes it poor for welding.

It will be ideal to use 308L and 309 grades if welding will be involved. Stick with annealed welding to prevent 303 from corroding.

303 Grade SS Machining

 Laser cutting SS
Laser cutting SS

Machining this stainless steel grade is easy as long as you adhere to:

  1. Keep the edges of all cutting tools very sharp. Work hardening is enhanced when you use tools with dull edges.
  2. Even with light cuts, ensure they are deep enough. This helps in preventing work hardening.
  3. As you go through cutting, coolants need to be on hand. It prevents heat from building up.

There is much similarity in this cutting properties of 304 to 309.

Heat treatment for 303 SS

The 303 SS grade doesn’t react well with heat treating. Annealing can be attained through quick cooling.

Cold Working Vs. Hot Working 303 Stainless Steel

The chart below shows the major differences between hot and cold working 303.

Cold Working Hot Working
Because cold working is done below the recrystallization temperature, there is not a significant amount of metal recovery. Hot working is done at the degree of recrystallization yet below the melting point, thus both metal deformation and restoration happen at the same time.
It takes substantially more stress to create deformation. Less stress is necessary for deformation since higher deformation temperature are used.
Tensile stresses form in the metal during the procedure. Tensile stress do not form in the metal even during the procedure.
Grain distortion happens due to cold working. Metal grains are refined by hot working, producing new characteristics.
Metal hardening happens. Metal hardening doesn’t happen.
It raises the metal’s ultimate tensile strength, bending stress, and endurance force but lowers its corrosion resistance. The metal’s ultimate tensile strength, hardness, corrosion resistance, or wear resistance are unaffected by the procedure if it is done correctly.
Impact resistance and elasticity are decreased during the procedure. Moreover, it enhances a few mechanical qualities including impact resistance and elasticity.

Forms in Which you Supply 303 Stainless Steel Grade?

Available options include:

  1. Hexagonal bars
  2. Square bars
  3. Round bars
  4. Flat bars, sheets or plates
  5. Tubes and pipes

303 Stainless Steel Uses

SS is a functional material you can use in many applications including:

  1. Springs
  2. Shafts
  3. Gears
  4. Bolts & Nuts
  5. Bushings
  6. Aircraft fittings.

Conclusion

303 stainless steel is the ideal choice if you want that steel kind that is easy to machine. Due to the high level of sulphur, along with other elements, using this steel is indeed a delight.

Even though welding features are not so great, this can be worked around based on what it is needed for.

More Resources:

How is Stainless Steel Made – Source: Tuolian

303 SS – Source: AZO Material

303 Vs. 304 SS – Source: TurnTech

Stainless Steel 303 – Source: Krupp

One Stop Stainless Steel Supply.

Whether you need stainless steel materials for your business or fabrication projects, TuoLian is your best supplier. You can find all types, grades, and thicknesses based on your needs. Guaranteed that we provide the best quality at a reasonable cost.
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