Stainless Steel Composition
Stainless steel refers to a wide variety of grades of iron that contain an alloy that has at least 10.5% chromium with low carbon content and other elements include Carbon (C), Silicon (Si), Manganese (Mn), Phosphorus (P), Sulfur (S), Nickel (Ni), Molybdenum (Mo), Titanium (Ti), Nitrogen (N), and Cuprum (Cu) are added in the chemical composition, the composition provides unique characteristics of the material.
Stainless Steel Composition
The chemical compositions for some commonly used austenitic, ferritic, martensitic, and duplex stainless steels are provided in the following tables based on ASTM standards.
Austenitic Stainless Steel Grades
| UNS No | AISI No. | C | Si | Mn | P | S | Cr | Mo | Ni | Others |
|---|---|---|---|---|---|---|---|---|---|---|
| S30100 | 301 | 0.15 | 1.00 | 2.00 | 0.045 | 0.030 | 16.0/18.0 | – | 6.0/8.0 | N 0.10 |
| S30400 | 304 | 0.07 | 0.75 | 2.00 | 0.045 | 0.030 | 17.5/19.5 | – | 8.0/10.5 | N 0.10 |
| S30403 | 304L | 0.030 | 0.75 | 2.00 | 0.045 | 0.030 | 17.5/19.5 | – | 8.0/12.0 | N 0.10 |
| S30453 | 304LN | 0.030 | 0.75 | 2.00 | 0.045 | 0.030 | 18.0/20.0 | – | 8.0/12.0 | N 0.10/0.16 |
| S30500 | 305 | 0.12 | 0.75 | 2.00 | 0.045 | 0.030 | 17.0/19.0 | – | 10.5/13.0 | – |
| S31600 | 316 | 0.08 | 0.75 | 2.00 | 0.045 | 0.030 | 16.0/18.0 | 2.00/3.00 | 10.0/14.0 | N 0.10 |
| S31603 | 316L | 0.030 | 0.75 | 2.00 | 0.045 | 0.030 | 16.0/18.0 | 2.00/3.00 | 10.0/14.0 | N 0.10 |
| S31635 | 316Ti | 0.08 | 0.75 | 2.00 | 0.045 | 0.030 | 16.0/18.0 | 2.00/3.00 | 10.0/14.0 | Ti 5x (C+N) / 0.70 N 0.10 |
| S31653 | 316LN | 0.030 | 0.75 | 2.00 | 0.045 | 0.030 | 16.0/18.0 | 2.00/3.00 | 10.0/14.0 | N 0.10/0.16 |
| S31700 | 317 | 0.08 | 0.75 | 2.00 | 0.045 | 0.030 | 18.0/20.0 | 3.0/4.0 | 11.0/15.0 | N 0.10 |
| S31703 | 317L | 0.030 | 0.75 | 2.00 | 0.045 | 0.030 | 18.0/20.0 | 3.00/4.00 | 11.0/15.0 | N 0.10 |
| S31753 | 317LN | 0.030 | 0.75 | 2.00 | 0.045 | 0.030 | 18.0/20.0 | 3.0/4.0 | 11.0/15.0 | N 0.10/0.22 |
| S32100 | 321 | 0.08 | 0.75 | 2.00 | 0.045 | 0.030 | 17.0/19.0 | – | 9.0/12.0 | Ti 5 X C Min/0.70 N 0.10 |
| S34700 | 347 | 0.08 | 0.75 | 2.00 | 0.045 | 0.030 | 17.0/19.0 | – | 9.0/13.0 | Nb+Ta 10 X C Min/1.0 |
Chemical Composition % By Mass Max
Super Austenitic Grades
| UNS No | AISI No. | C | Si | Mn | P | S | Cr | Mo | Ni | Others |
|---|---|---|---|---|---|---|---|---|---|---|
| N08904 | 904L | 0.020 | 1.00 | 2.00 | 0.045 | 0.035 | 19.0/23.0 | 4.0/5.0 | 23.0/28.0 | Cu 1.0/2.0 N 0.10 |
Chemical Composition % By Mass Max
Duplex Grades
| UNS No | AISI No. | C | Si | Mn | P | S | Cr | Mo | Ni | Others |
|---|---|---|---|---|---|---|---|---|---|---|
| S31803 | 2205 | 0.030 | 1.00 | 2.00 | 0.030 | 0.020 | 21.0/23.0 | 2.5/3.5 | 4.5/6.5 | N 0.08/0.20 |
| S32304 | 2304 | 0.030 | 1.00 | 2.50 | 0.040 | 0.030 | 21.5/24.5 | 0.05/0.60 | 3.0/5.5 | N 0.05/0.20; Cu 0.05/0.60 |
| S32750 | 2507 | 0.030 | 0.80 | 1.20 | 0.035 | 0.020 | 24.0/26.0 | 3.0/5.0 | 6.0/8.0 | N 0.24/0.32; Cu 0.50 |
Chemical Composition % By Mass Max
Ferritic Stainless Steel Grades
| UNS No | AISI No. | C | Si | Mn | P | S | Cr | Mo | Ni | Others |
|---|---|---|---|---|---|---|---|---|---|---|
| S40300 | 403 | 0.15 | 0.50 | 1.00 | 0.040 | 0.030 | 11.5/13.0 | – | – | – |
| S40500 | 405 | 0.08 | 1.00 | 1.00 | 0.040 | 0.030 | 11.5/14.5 | – | – | Al 0.10./0.30 |
| S40800 | – | 0.08 | 1.00 | 1.00 | 0.045 | 0.045 | 11.5/13.0 | – | 0.50 | Ti 12xC/1.10 |
| S41008 | 410S | 0.08 | 1.00 | 1.00 | 0.040 | 0.030 | 11.5/13.5 | – | 0.60 | – |
| S43000 | 430 | 0.12 | 1.00 | 1.00 | 0.040 | 0.030 | 16.0/18.0 | – | – | – |
| S43400 | 434 | 0.12 | 1.00 | 1.00 | 0.040 | 0.030 | 16.0/18.0 | 0.75/1.25 | – | – |
| S43600 | 436 | 0.12 | 1.00 | 1.00 | 0.040 | 0.030 | 16.0/18.0 | 0.75/1.25 | – | Nb+Ta 5xC/0.80 |
| S44200 | 442 | 0.20 | 1.00 | 1.00 | 0.040 | 0.035 | 18.0/23.0 | – | 0.60 | – |
Chemical Composition % By Mass Max
Heat Resisting Grades
| UNS No | AISI No. | C | Si | Mn | P | S | Cr | Mo | Ni | Others |
|---|---|---|---|---|---|---|---|---|---|---|
| S30409 | 304H | 0.04/0.10 | 0.75 | 2.00 | 0.045 | 0.030 | 18.0/20.0 | – | 8.0/10.5 | – |
| S30451 | 304N | 0.08 | 0.75 | 2.00 | 0.045 | 0.030 | 18.0/20.0 | – | 8.0/10.5 | N 0.10/0.16 |
| S30900 | 309 | 0.20 | 1.00 | 2.00 | 0.045 | 0.030 | 22.0/24.0 | – | 12.0/15.0 | – |
| S30908 | 309S | 0.08 | 0.75 | 2.00 | 0.045 | 0.030 | 22.0/24.0 | – | 12.0/15.0 | – |
| S30909 | 309H | 0.04/0.10 | 0.75 | 2.00 | 0.045 | 0.030 | 22.0/24.0 | – | 12.0/15.0 | – |
| S31000 | 310 | 0.25 | 1.50 | 2.00 | 0.045 | 0.030 | 24.0/26.0 | – | 19.0/22.0 | – |
| S31008 | 310S | 0.08 | 1.50 | 2.00 | 0.045 | 0.030 | 24.0/26.0 | – | 19.0/22.0 | – |
| S31400 | 314 | 0.25 | 1.50/3.00 | 2.00 | 0.045 | 0.030 | 23.0/26.0 | – | 19.0/22.0 | – |
| S31609 | 316H | 0.04/0.10 | 0.75 | 2.00 | 0.045 | 0.030 | 16.0/18.0 | 2.00/3.00 | 10.0/14.0 | – |
| S31651 | 316N | 0.08 | 0.75 | 2.00 | 0.045 | 0.030 | 16.0/18.0 | 2.00/3.00 | 10.0/14.0 | N 0.10/0.16 |
| S32109 | 321H | 0.04/0.10 | 0.75 | 2.00 | 0.045 | 0.030 | 17.0/19.0 | – | 9.0/12.0 | Ti 4x(C+N) / 0.70 |
| S34709 | 347H | 0.04/0.10 | 0.75 | 2.00 | 0.045 | 0.030 | 17.0/19.0 | – | 9.0/13.0 | Nb 8xC /1.00 |
| S44600 | 446 | 0.20 | 1.00 | 1.50 | 0.040 | 0.030 | 23.0/27.0 | – | 0.75 | N 0.25 |
| N08800 | 800 (332) | 0.10 | 1.00 | 1.50 | 0.045 | 0.015 | 19.0/23.0 | – | 30.0/35.0 | Fe 39.5 Min; Al 0.15/0.60; Ti 0.15/0.60 |
| N08810 | 800H | 0.05/0.10 | 1.00 | 1.50 | 0.045 | 0.015 | 19.0/23.0 | 30.0/35.0 | 30.0/35.0 | Cu 0.75; Fe 39.5 Min; Al 0.15/0.60; Ti 0.15/0.60 |
Chemical Composition % By Mass Max
Reading more: Stainless steel equivalent grades
Stainless Steel Chemical Elements
Various chemical elements play an important role in stainless steel, each of the different grades of stainless steel contains different alloying elements that contribute to its properties such as resistance to corrosion, strength, and flexibility, several critical elements with explanations are listed below:
Carbon (C)
- Yield point and tensile strength increased with Carbon content increasing, but ductility and impact resistance decreased.
- When carbon content exceeds 0.23%, the welding performance of steel will be not good, Carbon content is generally not more than 0.20%.
- High carbon content can also affect the corrosion resistance of the steel, and make it easy to rust.
- In addition, carbon can increase cold brittleness and aging of steel, like 304 and 304L, 304L is low carbon 304.
Silicon (Si)
- In the process of making steel, silicon as a reducing agent and oxidizing agent, containing 0.15 – 0.30% of silicon content
- If silicon content is more than 0.50-0.60%, silicon significantly improves elastic limit, yield point, and tensile strength, so it is widely used in spring steel.
- Adding 1.0 – 1.2% silicon in the quenched and tempered steel, strength can be increased by 15 – 20%.
- The combination of Silicon, Molybdenum, Tungsten and Chromium has the effect of improving the corrosion resistance and oxidation resistance.
- Low carbon steel containing silicon 1 – 4%, with high permeability, used in electrical industry silicon steel sheet
- Silicon content increasing, not good for welding.
Manganese (Mn)
- In the process of making steel, manganese is a good agent and desulfurization agent, manganese content in common steel of 0.30 – 0.50%.
- Carbon steel, adding more than 0.70% manganese, not only has enough toughness, and has higher strength and hardness, improves steel quenching and performance of thermal processing
- Manganese content increased, weakened the corrosion resistance of steel, and reduced the welding performance. Manganese can improve the strength of steel.
Phosphorus (P)
In general, phosphorus is a harmful element in steel, increasing the cold brittleness of steel to result in welding performance deterioration, and reducing ductility to influence the cold bending performance. It usually requires the phosphorus content in steel to be less than 0.045%.
Sulfur (S)
- Sulfur in normal circumstances is also a harmful element. generating heat, reducing ductility and toughness
- Sulfur on the welding performance is also bad, reducing corrosion resistance. So the sulfur content is less than 0.055%
- The requirement of high-quality steel is less than 0.040% of sulfur. The addition of 0.08-0.20% to the steel can improve the machinability, often referred to as free-cutting steel
Chromium (Cr)
- Chromium can improve oxidation resistance and corrosion resistance, so it is an important alloying element of stainless steel
- In structural steel and tool steel, chromium can significantly improve the strength, hardness, and wear resistance, but at the same time reduce ductility and toughness
Nickel (Ni)
- Nickel element can improve the strength of steel, and maintain a good ductility and toughness. Nickel has a higher corrosion resistance to acid and alkali, and has the ability of anti rust and heat resistance at high temperature
- Improve toughness, so that the steel has a high strength, but also to maintain a good ductility and toughness
- Nickel can improve the corrosion resistance and low temperature impact toughness
- Nickel based alloys have a higher thermal performance
Molybdenum (Mo)
- Molybdenum can make the grain refinement, improve the quenching and thermal properties
- Under high temperature to maintain sufficient strength and creep resistance (long-term at high temperature under stress, deformation, said creep)
- Mechanical properties can be improved with the addition of molybdenum in structural steel
Titanium (Ti)
- Titanium steel is strong deoxidizing agent, making the internal structure of the steel dense, fine grain size, and reduce the aging sensitivity and cold brittleness
- Improving the welding performance
- Adding proper titanium to Austenitic stainless steels, avoiding Intergranular corrosion
Copper (Cu)
- Copper can improve the strength and toughness, especially to atmospheric corrosion performance
- Disadvantage is prone to cracking during thermal processing, the copper content more than 0.5% ductility significantly reduced
- When the copper content is less than 0.50%, no effect on the welding property
Nitrogen (N)
Nitrogen can improve the strength of steel.