Stainless free cutting steel or stainless machining steel is a kind of alloy steel in which sulfur, lead, calcium, selenium, tellurium and other free cutting elements are added to improve its cutting ability. These free cutting element compounds lubricate the cutting tool and reducing the cutting resistance of the stainless steel, thereby reducing the surface roughness and improving tool service life even at higher cutting speeds and greater depth of cutting. Stainless free-cutting steels have been widely used in machine parts that require corrosion resistance and free cutting.
The commonly used stainless free-cutting steels mainly include Austenite SUS303, 430F, Martensite 410F2, 416, SUS 420F2. The sulfur content of more than 0.3% added to SUS303 and 430 is to improve the machinability, but too high sulfur will reduce the corrosion resistance and other characteristics, so each free cutting element family should be added according to the optimal combination. We should increase the total amount of free cutting elements family and limit the deterioration of characteristics to the minimum level. The most commonly used is to add S and Pb, Se and Te in Ferrite and Martensite.
Austenitic Stainless Steel Grades
| UNS | C | Si | Mn | P | S | Cr | Ni | Mo | Se | Cu | Al |
| S20300
XM-1 |
≤0.08 | ≤1.00 | 5.00-
6.50 |
≤0.04 | 0.18
0.35 |
16.00
18.00 |
5.00
6.50 |
/ | / | 1.75
2.25 |
/ |
| S30300
303 |
≤0.15 | ≤1.00 | ≤2.00 | ≤0.20 | ≥0.15 | 17.00
19.00 |
8.00
10.00 |
/ | / | / | / |
| S30310
XM-5 |
≤0.15 | ≤1.00 | 2.5-
4.5 |
≤0.20 | ≥0.25 | 17.00
19.00 |
7.00
10.00 |
/ | / | / | / |
| S30323
303Se |
≤0.15 | ≤1.00 | ≤2.00 | ≤0.20 | ≤0.06 | 17.00
19.00 |
8.00
10.00 |
/ | ≥0.15 | / | / |
| S30345
XM-2 |
≤0.15 | ≤1.00 | ≤2.00 | ≤0.05 | 0.11
0.16 |
17.00
19.00 |
8.00
10.00 |
0.40
0.60 |
/ | / | 0.60
1.00 |
Martensitic Stainless Steel Grades
| UNS | C | Si | Mn | P | S | Cr | Ni | Se | Cu |
| S41600
416 |
≤0.15 | ≤1.00 | ≤1.25 | ≤0.06 | ≥0.15 | 12.00
14.00 |
/ | / | / |
| S41610
XM-6 |
≤0.15 | ≤1.00 | 1.50
2.50 |
≤0.06 | ≥0.15 | 12.00
14.00 |
/ | / | / |
| S41623
416Se |
≤0.15 | ≤1.00 | ≤1.25 | ≤0.06 | ≤0.06 | 12.00
14.00 |
/ | ≥0.15 | / |
| S42020
420F |
0.30
0.40 |
≤1.00 | ≤1.25 | ≤0.06 | ≥0.15 | 12.00
14.00 |
(≤0.5) | / | (≤0.6) |
| S44020
440F |
0.95
1.20 |
≤1.00 | ≤1.25 | ≤0.06 | ≥0.15 | 16.00
18.00 |
(≤0.5) | / | (≤0.6) |
Ferritic Stainless Steel Grades
| UNS | C | Si | Mn | P | S | Cr | Ni | Mo | Se | Ti | N |
| S18200
XM-34 |
≤0.08 | ≤1.00 | ≤2.50 | ≤0.04 | ≥0.15 | 17.50
19.50 |
/ | 1.50
2.50 |
/ | / | / |
| S18235 | ≤0.025 | ≤1.00 | ≤0.50 | ≤0.03 | 0.15
0.35 |
17.50
18.50 |
≤1.00 | 2.00
2.50 |
/ | 0.30
1.00 |
≤0.025注 |
| S41603 | ≤0.08 | ≤1.00 | ≤1.25 | ≤0.06 | ≥0.15 | 12.00
14.00 |
/ | / | / | / | / |
| S43020
430F |
≤0.12 | ≤1.00 | ≤1.25 | ≤0.06 | ≥0.15 | 16.00
18.00 |
/ | / | / | / | / |
| S43023
430FSe |
≤0.12 | ≤1.00 | ≤1.25 | ≤0.06 | ≤0.06 | 16.00
18.00 |
/ | / | ≥0.15 | / |
(Note：C+N≤0.035)
