Stainless Steel is a metal or iron alloys made with 10.5% chromium. In order to enhance the structure and other properties like strength, formability, toughness etc, other alloying elements are also added to stainless steel. The metallic additions made in stainless steel are nickel, molybdenum, titanium, and copper etc.

Some non-metal additions are also made in it like carbon and nitrogen. The stainless steel suppliers should make sure that their stainless steel supplies should fulfill the basic requirement i.e. it should be corrosion resistant. Additional physical properties are required to achieve the overall quality of a product.

In this article, you will read about the different types of stainless steel grades so that you can buy stainless steel supplies easily.

Stainless Steel Grades

The manufacturer uses various steel grades to make steel supplies. Stainless steel grades are based upon the amount of alloying elements that are added to give corrosion resistance balance, mechanical properties etc. Grading of stainless steel is divided into five groups, namely:

Austenitic Grade:

It is easy to work and weld on austenitic grade stainless steel. It has many good properties like ductility, toughness, good strength and corrosion resistance. It contains 17-25 % chromium and 8-20 % nickel and other alloys in order to get expected results. This kind of steel is generally non-magnetic but it becomes slightly magnetic when cold worked. This category further contains the following grades:

  • 304 Grade: It is used in a variety of application; in fact, it is the most commonly used stainless steel by suppliers and manufacturers. It contains 18% chromium and 8% nickel, therefore, it is also known as 18/8 stainless steel.
  • 304L Grade: It has the same corrosion resistance as 304 grade, but it has less susceptibility to sensitization when it is welded. This is limited to service up to the temperature of 425 degree Celsius.
  • 316 Grade: It is a marine alloy as its corrosion resistance capacity is more than 304 steel. It is increased by 2 % of molybdenum that’s why it is more corrosion resistant. This grade is used in the chemical, textile, and paper industry.
  • 316L Grade: It is a low carbon steel but has the same corrosion resistance property. The thermal treatment and physical property of this grade are the same as 316 grade.
  • 303 Grade: This grade of stainless steel is used where production requires extensive machining in automatic screw machines. This grade cannot be used in water.
  • 253 MA®: It is suitable for high-temperature applications as it has excellent strength at elevated temperatures.

Ferritic Grade:

The ferritic grade steel generally lacks toughness that’s why it is not used in structural applications and hence it is supplied in sheets and coils of 1.6 mm thickness. It is further divided into two grades:

  • 409 Grade: It contains 10.5 % chromium and mainly used in an automotive exhaust system. It has the same ductility and strength as carbon steel.
  • 430 Grade: It is used in a mild indoor environment, automotive trim and dishwasher liners. It has less corrosion resistance than 304 as it contains 17 % chromium.

Duplex and Super Duplex Grade:

It is a combination of both austenite and ferrite grade stainless steel. It contains 18-29 % chromium and 3-8 % nickel. The steel of this grade is magnetic in all conditions and are easy to weld and fabricate. This is further categorized into the following:

  • 2205 Grade: Being known as duplex stainless steel, it has a high strength and well suited in a high chloride environment. It is used in chemical tankers, heat exchangers, and in oil and gas equipment. Best to use when 316 and 316L can’t serve your purpose for corrosion resistance.
  • S32750 Grade: It is used in petrochemical plants, desalination plants, and structural components that require high strength and corrosion resistant steel.

Martensitic Grade:

It responds well to heat treatments and gives high mechanical strength and hardness. This group of stainless steel contains chromium and carbon. It consists of 410, 420 C, and 431 grade and generally used for stainless steel supplies such as cutlery, bolts, bushings, furnace parts, springs, shaft, valves etc. It can be heated to the highest mechanical properties.

Precipitation Hardening Grade:

This group of stainless steel contains chromium and nickel with the addition of aluminum, copper, titanium, and niobium. It has high strength, ductility, and toughness. This grade of stainless steel is used in aerospace, boat shafting, and other high-tech industries.

Steel supplies or steel products are carefully manufactured and designed keeping in mind the various uses of different steel grades.