The Ultimate Guide to Stainless Steel Grades and Their Uses
When you are in the market to buy stainless steel, the major factors that you might consider are its appearance, strength, and resistance to corrosion and oxidation. So, randomly buying any product won’t do you any good. For this, it is important that you choose the right grade of stainless steel. In this article, you can find the different grades of stainless steel and their uses.
What is Stainless Steel?
Stainless steel is corrosion-resistant and rustless steel, an alloy of iron containing 10.5% chromium and usually Nickel, and 0.2 to 2.11% Carbon. It is the presence of chromium that makes this steel resistant to corrosion by forming a passive film that protects the material and self-heals in the presence of oxygen.
The major issue that affects different steel parts is corrosion. It is the ability to resist corrosion that makes stainless steel a popular choice. You can convert it into coils, tubes, circles, plates, and sheets.
Stainless steel alloys usually have two main labels:
- Families
- Grades
What are the Different Stainless Steel Families and Grades?
Here are the different stainless steel families:
- Austenitic – They are the most common type of stainless steel, which can be hardened when cold worked and not by heat treatment. They have high formability, weldability, and excellent chemical resistance.
- Martensitic - They have high strength, brittleness, and better corrosion resistance. Hardness and strength can be increased on treatment with heat.
- Ferritic - They have high thermal conductivity, low coefficient of thermal expansion, and superior resistance to stress corrosion cracking.
- Duplex - They have strength twice that of regular austenitic and ferritic stainless steel. Also, they have good resistance to stress corrosion cracking, but their corrosion resistance varies based on the composition.
- Precipitation hardened - They have corrosion resistance similar to austenitic stainless steel. They are of three types, namely, austenitic, semi-austenitic, and martensitic PH stainless steels.
There are different grades of stainless steel for each family. Let’s see those in detail.
Austenitic Stainless Steel
| 301 | 17% Chromium 7% Nickel | ● Better corrosion resistance in mildly corrosive environments at ambient temperatures ● Low corrosion resistance in extremely corrosive environments at high-temperature ● High strength ● Good formability and weldability | ● Aircraft structural parts ● Utensils and tableware ● Trailer bodies ● Roof, drainage/door frames, etc. ● Auto body trim and wheel covers ● Conveyor parts |
| 302 | 18% Chromium 8% Nickel | ● High toughness ● Good tensile strength ● High yield strength, and ● High corrosion resistance | ● Stamping industry ● Spinning industry, and ● Wire forming industry ● Food and drink applications ● Form washers, springs, screens and cables |
| 303 | 17% Chromium 8% Nickel | ● Easily machined due to the presence of Sulphur ● Lower corrosion resistance and toughness | ● Nuts and bolts ● Aircraft fittings ● Screws ● Gears ● Bushings ● Shafts |
| 304 | 17.5-19.5% Chromium 8-10.5% Nickel | ● Excellent chemical resistance ● High oxidation resistance ● Excellent corrosion resistance ● Improved toughness ● High ductility | ● Food handling and processing equipment ● Screws ● Machinery parts ● Utensils ● Exhaust manifolds |
| 305 | 18% Chromium a minimum of 10% nickel | ● High strength ● Good corrosion resistance ● Good chemical resistance ● Low rate of work hardening | ● Deep drawing application ● Chemical, petroleum, textile, dairy, and food industries |
| 309 | 22% Chromium 12% Nickel | ● Improved temperature resistance ● Excellent oxidation resistance ● Excellent corrosion resistance ● High tensile strength | ● Furnace components ● Boiler baffles ● Oven linings ● Firebox sheets ● High-temperature containers |
| 316 | 16 to 18% chromium, 10 to 14% nickel | ● High resistance to crevice corrosion in saline environments due to the presence of Molybdenum ● Higher tensile and yield strength (316 H) | ● Food industry ● Surgical equipment ● Marine steel for swimming pool and seawater applications |
| 321 | Titanium-stabilized | ● Good corrosion resistance ● High resistance to chromium carbide precipitation at high temperatures ● High creep and stress rupture properties | ● Aircrafts ● Expansion joints ● Heat Exchangers ● Furnace parts ● Spiral welded tube for flues, burner pipes, etc |
Martensitic Stainless Steel
| Grade | Composition (of chromium and Nickel) | Properties | Uses |
| 410 | 11.5-13.5% Chromium 0.75% Nickel | ● Useful in mild to moderate corrosive environments | ● Refinery equipment ● Turbines ● Pumps ● Valves ● Bolts ● Screws ● Nuts ● Bushings |
| 420 | 12-14% Chromium | ● Resists corrosion in the presence of mild acids, freshwater, alkali, food products, and normal atmospheric conditions ● Good ductility | ● Surgical instruments ● Needle valves ● Shear blades ● Surgical equipment ● Cutlery |
| 440 | 16-18% Chromium | ● High strength, wear resistance, and hardness after treatment with heat | ● High-quality knife blades ● Pivot pins ● Dental and surgical instruments ● Valve seats ● Nozzles ● Oil pumps ● Ball bearings |
Ferritic Stainless Steel
| Grade | Composition (of chromium and Nickel) | Properties | Uses |
| 409 | 12% Chromium 0.5% Nickel | ● Good mechanical properties at high temperatures ● High corrosion resistance at high temperatures ● good formability and weldability | ● Automotive exhaust systems ● Fuel filters ● Agricultural machinery (spreaders) ● Heat Exchangers |
| 430 | 17% Chromium 0.5% Nickel | ● High-stress corrosion cracking resistance ● Good machinability and formability ● Low work hardening rate ● Low ductility rate | ● Decorative items ● Car accessories ● Cookers ● Washing machines ● Dishwashers ● Industrial roofing ● Flue linings ● Wall cladding ● Hinges ● Fasteners |
These are some of the stainless steel grades. But it is not just these; many other grades also belong to the stainless steel family. So, the next time you choose a steel, do not just randomly choose one. Each grade has its own specific characteristics, which are meant to serve a certain list of applications. The wide range of applications makes stainless steel important in diverse industries such as food processing, transportation, medical, construction, and much more.
Metal and Steel India is a popular company whose primary focus is to supply the best raw materials for producing stainless steel. You can contact us for your stainless steel needs.
Experience our services at least once; you will never think of backing off.