When you need custom stainless steel castings, do you know the grades of stainless steel? How to choose stainless steel casting grades according to the application?
If you have the above questions, please read this article carefully. Besser Casting, as the leader of stainless steel investment casting in China, our team of professional engineers has specially written this article for you.
What is Stainless Steel Casting
Stainless steel castings are also known as stainless steel investment castings. It is a casting using a silica sol process, a casting process with little or no cutting. In the foundry industry, this is an excellent investment casting process technology. Its applications are very broad and diverse. It is not only suitable for casting of various types and alloys, but also produces castings with higher dimensional accuracy and surface quality than other casting methods.
Common Stainless Steel Casting Grades
There are several "families" of stainless steel castings. Each of these families has different proportions of iron, chromium and carbon. Some contain other elements such as nickel, molybdenum, manganese or copper.
The most common grades are:
- Austenitic stainless steel: 304, 302, 303, 310, 316, 317, 321, 347
- Ferritic Stainless Steel: 430, 444, 409
- Martensitic stainless steel: 420, 431, 440, 416
- Duplex stainless steel: 2304, 2205
1. Austenitic Stainless Steel Casting
Austenitic stainless steel castings are non-magnetic. When nickel is added to stainless steel in sufficient amounts the crystal structure changes to “austenite”. The basic composition of austenitic stainless steel casting grade is 18% chromium and 8% nickel. This enhances their corrosion resistance and modifies the structure from ferritic to austenitic. Austenitic stainless steel casting grades are the most commonly used stainless steels casting material accounting for more than 70% of production (type 304 is the most commonly specified stainless steel casting grade by far). They are not hardenable by heat treatment.
| Austenitic Stainless Steel Casting Grades | |||||||||
| C | M | Si | Cr | Ni | Mo | P | S | Cu | |
| Min-Max | Min-Max | Min-Max | Min-Max | Min-Max | Min-Max | Max | Min-Max | Min-Max | |
|
CF-16Fa (303) |
0.16 Max | 1.5 Max | 2.0 Max | 18.0 -21.0 | 9.0-12.0 | 0.40-0.80 | 0.04 | 0.20-0.40 | |
|
CF-8 (304) |
0.08 Max | 1.5 Max | 2.0 Max | 18.0-21.0 | 8.0-11.0 | 0.04 | 0.04 Max | ||
|
CF-3 (304L) |
0.03 Max | 1.5 Max | 2.0 Max | 17.0-21.0 | 8.0-12.0 | 0.04 | 0.04 Max | ||
|
CF-8M (316) |
0.08 Max | 1.5 Max | 2.0 Max | 18.0-21.0 | 9.0-12.0 | 2.0-3.0 | 0.04 | 0.04 Max | |
|
CF-3M (316L) |
0.03 Max | 1.5 Max | 1.5 Max | 17.0-21.0 | 9.0-13.0 | 2.0-3.0 | 0.04 | 0.04 Max | |
|
CF-8C (347) |
0.08 Max | 1.5 Max | 2 Max | 18.0-21.0 | 9.0-12.0 | 0.04 | 0.04 Max | ||
|
CG-8M (317) |
0.08 Max | 1.5 Max | 1.5 Max | 18.0-21.0 | 9.0-13.0 | 3.0-4.0 | 0.04 | 0.04 Max | |
2. Ferritic Stainless Steel Casting
Ferritic stainless steel casting are plain chromium stainless steel casting process with a chromium content varying between 10.5 and 18% and a low carbon content. They are magnetic and not hardenable by heat treatment. Ferritic stainless steel casting grades have good ductility and formability but a relatively poor high temperature strength compared to that of austenitic grades.
| Ferritic Stainless Steel Casting Grades | |||||||||
| C | M | Si | Cr | Ni | Mo | P | S | Cu | |
| Max | Max | Max | Min-Max | Max | Max | Max | Max | Max | |
|
409 /Nb |
0.16 | 1.5 | 2 | 10.5-11.75 | 0.5 | 0.045 | 0.045 | ||
|
442 (CB-30) |
0.3 | 1 | 1.5 | 18.0-22.0 | 2 | 0.04 | 0.04 | ||
|
446 (CC-50) |
0.5 | 1 | 1.5 | 26.0-30.0 | 4 | 0.04 | 0.04 | ||
3. Martensitic Stainless Steel Casting
Martensitic stainless steel casting were the first stainless steel casting type that were commercially developed and have a relatively high carbon content (0.1 – 1.2%) compared to other stainless steel casting types. Martensitic stainless steel casting contains chromium between 12 and 18%. They are magnetic and hardenable by quenching and tempering like plain carbon steels and find their main application in cutlery, aerospace and general engineering.
| Martensitic Stainless Steel Casting Grades | |||||||||
| C | M | Si | Cr | Ni | Mo | P | S | Cu | |
| Min-Max | Max | Min-Max | Min-Max | Min-Max | Min-Max | Max | Min-Max | Min-Max | |
| 410 | 0.05-0.15 | 1 | 1.5 Max | 11.5-14.0 | 1.0 Max | 0.5 Max | 0.04 | 0.04 Max | 0.50 Max |
| 416 | 0.15 Max | 1.25 | 1.50 Max | 11.5-14.0 | 0.50 Max | 0.50 Max | 0.05 | 0.15-0.35 | 0.50 Max |
| 420 | 0.15 Max | 1 | 1.0 Max | 12.0-14.0 | 0.04 | 0.03 Max | |||
| 15-5 PH | 0.05 Max | 0.6 | 0.50-1.00 | 14.00-15.50 | 4.20-5.00 | 0.025 | 0.025 Max | 2.5-3.2 | |
| 17-4 PH | 0.06 Max | 0.7 | 0.50-1.00 | 15.5-16.7 | 3.60-4.60 | 0.04 | 0.03 Max | 2.8-3.5 | |
4. Duplex Stainless Steel Casting
These are stainless steels containing relatively high chromium levels (between 18 and 28%) and moderate amounts of nickel (between 4.5 and 8%). The high corrosion resistance and the excellent mechanical properties combination of duplex stainless steels can be explained by their chemical composition and balanced (‘duplex’) microstructure of approximately equivalent volume fractions of ferrite and austenite.
| Duplex Stainless Steel Casting Grades | |||||||||
| C | Ma | Si | Cr | Ni | Mo | P | S | Cu | |
| Max | Max | Max | Min-Max | Min-Max | Min-Max | Max | Max | Min-Max | |
| ASTM A890 Grade 1A (CD4MCu) | 0.04 | 1 | 1 | 24.5-26.5 | 4.75-6.00 | 1.75-2.25 | 0.04 | 0.04 | 2.75-3.25 |
| ASTM A890 Grade 4A (CD3MN) | 0.03 | 1.5 | 1 | 21.0-23.0 | 4.5- 6.5 | 2.5-3.5 | 0.04 | 0.02 | 1.00 Max |
Conclusion
Besser Casting is a top stainless steel casting manufacturer in China. With more than 20 years of manufacturing experience. Can help you complete the stainless steel castings required for your project. If you need our help and services, please contact us immediately. We will reply you within 24 hours. We look forward to hearing from you!