Date Published:May. 10. 2016
Stainless Steel
About stainless steel
Stainless steel refers to alloy steel containing chrome (Cr) and nickel (Ni) in addition to the 6 iron elements whose Cr content is approximately above 11%. Basically stainless steel should be Fe-Cr alloy containing Cr for about 11% and Ni, Mo, Cu, Al and/or Si, etc. are added to improve corrosion resistance, mechanical properties, processing properties and other properties. As the primary raw materials are Cr and Ni, they are classified into 2 major categories: Cr and Cr-Ni. They are also classified into categories of martensitic, ferrite and austenitic in terms of metal composition. Also, there are other stainless steel materials such as austenitic/ferrite stainless steel and precipitationhardened stainless steel, etc.
● Stainless steel categories
| Categories | Cr | Cr-Ni | |
|---|---|---|---|
| Metal composition | Martensitic |
Ferrite | Austenitic |
| Hardening | Quenching hardening |
Non-quenching hardening |
Processing hardening |
● Effects of each element on performance
| Element | Performance improvement |
|
|---|---|---|
| C | Low carbon | Corrosion resistance（resistance to grain boundary corrosivity） |
| High carbon | Strength and hardness |
|
| Mo | Corrosion resistance（resistance to porous corrosion） | |
| Cu | Acid resistance |
|
| Ti・Nb | Corrosion resistance（resistance to grain boundary corrosivity） | |
| Si・Al | Oxidation resistance |
|
| S・Se | Machinability |
|
Types and features of stainless steel
| Classification code | Features |
|---|---|
| SUS302 | Standard type 18Cr-8Ni steel. SUS303 and SUS304 are both improved variants of SUS302. Addition of Ni improves corrosion resistance and mechanical properties. |
| SUS303 | Machinability is improved by addition of S and P to SUS302. However, its corrosion resistance are relatively low. Mo is added to improve the corrosion resistance. |
| SUS304 SUS304L |
This is an improved variant of SUS302 and features smaller amount of carbon and is superior in corrosion resistance and weldability. This is the most standard product among austenitic stainless steel. SUS304L has carbon content lower than that of SUS304 and the resistance to grain boundary corrosion and weldability are improved. |
| SUS310S | This has good corrosion resistance and oxidation resistance as well as excellent high-temperature properties due to addition of Ni and Cr and is used as heat resistant steel. This reduces the processing hardening by cold processing while weakening its magnetic property, so it is used as low process hardening steel and nonmagnetic steel. |
| SUS316 SUS316L |
This has good corrosion resistance and acid resistance as well as high-temperature strength due to addition of Mo and is used as heat resistant steel. SUS316L has carbon content lower than that of SUS316 and the resistance to grain boundary corrosion and weldability are improved. |
| SUSXM7 | Cu is added to SUS304 to suppress the processing hardening in cold processing. |
| SUS430 | This is a standard type of 18Cr steel, having a good cold processing property and corrosion resistance. Because of its inexpensive price, it is widely used in many applications. |
| SUS434 | Mo is added to SUS430 to improve the corrosion resistance. |
| SUS410 | Representative martensitic stainless steel This has excellent mechanical properties and corrosion resistance after heat treatment. |
| SUS403 | Corrosion resistance and toughness after heat treatment are improved with Si and Cr composition range narrowed down. This is used for valves, pump shafts, edges, bolts, nuts, steam turbine blades and jet engine components, etc. |
| SUS416 | Machinability of 13Cr steel is improved by addition of S and P. Its corrosion resistance are relatively lower than the standard type. |
| SUS431 | Toughness and corrosion resistance are improved by addition of Ni and Cr, respectively and its corrosion resistance is the best among martensitic materials that endure heat treatment. This is used for papermaking machines, marine shafts and aerospace components, etc. |
| SUS440C | This has the highest hardness among stainless steel materials and excellent abrasion resistance, so this is used for dice and ball bearings, etc. |
| SUS631J1 | This is precipitation-hardened stainless steel with the highest heat resistance among JIS steel types and used for thin plates and wire springs. |
Chemical components and mechanical properties of various stainless steel materials
● Austenitic
| Classification code |
Chemical components（％） | Mechanical property | ||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| C | Si | Mn | P | S | Ni | Cr | Mo | Others | Tensile strength （N/mm2） |
Extension （％） |
Brinell hardness （HB） |
|
| SUS302 | 0.15 or less |
1.00 or less |
2.00 or less |
0.045 or less |
0.03 or less |
8.00 - 10.00 | 17.00 - 19.00 | - | - | 520 or above | 40 or above | 187 or less |
| SUS303 | 0.15 or less |
1.00 or less |
2.00 or less |
0.20 or less |
0.15 or above |
8.00 - 10.00 | 17.00 - 19.00 | 0.60 or less |
- | 520 or above | 40 or above | 187 or less |
| SUS304 | 0.08 or less |
1.00 or less |
2.00 or less |
0.045 or less |
0.03 or less |
8.00 - 10.50 | 18.00 - 20.00 | - | - | 520 or above | 40 or above | 187 or less |
| SUS304L | 0.03 or less |
1.00 or less |
2.00 or less |
0.045 or less |
0.03 or less |
9.00 - 13.00 | 18.00 - 20.00 | - | - | 480 or above | 40 or above | 187 or less |
| SUS310S | 0.08 or less |
1.50 or less |
2.00 or less |
0.045 or less |
0.03 or less |
19.00 - 22.00 | 24.00 - 26.00 | - | - | 520 or above | 40 or above | 187 or less |
| SUS316 | 0.08 or less |
1.00 or less |
2.00 or less |
0.045 or less |
0.03 or less |
10.00 - 14.00 | 16.00 - 18.00 | 2.00 - 3.00 | - | 520 or above | 40 or above | 187 or less |
| SUS316L | 0.03 or less |
1.00 or less |
2.00 or less |
0.045 or less |
0.03 or less |
12.00 - 15.00 | 16.00 - 18.00 | 2.00 - 3.00 | - | 480 or above | 40 or above | 187 or less |
| SUSXM7 | 0.08 or less |
1.00 or less |
2.00 or less |
0.045 or less |
0.03 or less |
8.50 - 10.50 | 17.00 - 19.00 | - | Cu：3.00 - 4.00 | 480 or above | 40 or above | 187 or less |
● Ferrite
| Classification code |
Chemical components（％） | Mechanical property |
||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| C | Si | Mn | P | S | Ni | Cr | Mo | Others | Tensile strength （N/mm2） |
Extension （％） |
Brinell hardness （HB） |
|
| SUS430 | 0.12 or less | 0.75 or less | 1.00 or less | 0.04 or less | 0.03 or less | 0.60 or less | 16.00 - 18.00 | - | - | 450 or above | 22 or above | 183 or less |
| SUS434 | 0.12 or less | 1.00 or less | 1.00 or less | 0.04 or less | 0.03 or less | 0.6 or less | 16.00 - 18.00 | 0.75 - 1.25 | - | 450 or above | 22 or above | 183 or less |
● Martensitic
| Classification code |
Chemical components（％） | Mechanical property | ||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| C | Si | Mn | P | S | Ni | Cr | Mo | Others | Tensile strength （N/mm2） |
Extension （％） |
Brinell hardness （HB） |
|
| SUS410 | 0.15 or less | 1.00 or less | 1.00 or less | 0.04 or less | 0.03 or less | 0.60 or less | 11.50 - 13.50 | - | - | 540 or above | 25 or above | 159 or above |
| SUS416 | 0.15 or less | 1.00 or less | 1.25 or less | 0.06 or less | 0.15 or above |
0.60 or less | 12.00 - 14.00 | 0.60 or less | - | 540 or above | 17 or above | 159 or above |
| SUS440C | 0.95 - 1.20 | 1.00 or less | 1.00 or less | 0.04 or less | 0.03 or less | 0.60 or less | 16.00 - 18.00 | 0.75 or less | - | 780 or above | 15 or less | 56HRC or above |
●Values in chart are for reference only. They are not guaranteed values.
Engineering Tips HINTS for NEW IDEAS
Examples to help you resolve any issues you may have.
Technical Data
Others
Machine Tools
Semiconductor Manufacturing Equipment
Food Machinery
Automotive Manufacturing Process
Medical equipment
FA Devices
Technical Data
Couplings
Special Screws
Machine Elements
FA solutions