Machinability and machining of 321 stainless steel
The machinability of grade 321 stainless steel is 36% in annealed conditions based on a 100% machinability rating for 1212 steel.
| Rated speeds and feeds for turning a variety of steels and cast irons with single-point and high-speed steel (HSS) case tools |
| Material |
Hardness, HB |
Illness |
Cutting depth, mm (in.) |
high speed steel tool |
Tool material |
| Speed |
To feed |
| m/min |
sfm |
mm/rotation |
in./rev |
ISO |
AISI |
| SS321 forged austenitic |
135-185 |
Annealed |
1 (0.04) |
34 |
110 |
0.18 |
0.007 |
S4, S5 |
M2, M3 |
| 4 (0.15) |
27 |
90 |
0.4 |
0.015 |
| 8 (0.30) |
21 |
70 |
0.5 |
0.02 |
| 16 (0.625) |
17 |
55 |
0.75 |
0.03 |
| Rated speeds and feeds for turning a variety of steels and cast irons with single-point and carbide-tipped case tools |
| Material |
Hardness, HB |
Illness |
Carbide Tool |
| Uncoated |
Coated |
| Speed |
To feed |
Tool material class |
Speed |
To feed |
Tool material class |
| Soldier |
Indexable |
| m/min |
sfm |
m/min |
sfm |
mm/rotation |
in./rev |
ISO |
W |
m/min |
sfm |
mm/rotation |
in./rev |
ISO |
W |
| SS321 forged austenitic |
135-185 |
Annealed |
105 |
350 |
120 |
400 |
0.18 |
0.007 |
K01, M10 |
C-3 |
160 |
525 |
0.18 |
0.007 |
CK01, CM10 |
CC-3 |
| 100 |
325 |
105 |
350 |
0.4 |
0.015 |
135 |
450 |
0.4 |
0.015 |
| 76 |
250 |
84 |
275 |
0.5 |
0.02 |
C-2 |
105 |
350 |
0.5 |
0.02 |
CC-2 |
| 60 |
200 |
64 |
210 |
0.75 |
0.03 |
K20, M20 |
– |
– |
– |
– |
– |
– |
| Rated speeds and feeds for turning a variety of steels and cast irons with ceramic tools |
| Material |
Hardness, HB |
Illness |
Cutting depth, mm (in.) |
Speed |
To feed |
Type of ceramic |
| m/min |
sfm |
mm/rotation |
in./rev |
| SS321 austenitic |
135-185 |
Annealed |
1 (0.040) |
425 |
1400 |
0.13 |
0.005 |
Cold pressed alumina |
| 4 (0.150) |
275 |
900 |
0.25 |
0.010 |
| 8 (0.300) |
185 |
600 |
0.40 |
0.015 |
| Rated speeds and feeds for turning a variety of steels and cast irons with high-speed steel and carbide cutting and forming tools |
| Material |
Hardness, HB |
Illness |
Speed |
Feed, mm/rev (in./rev) |
Tool material class |
| Cutting tool width |
Form tool width |
| m/min |
sfm |
1.5 mm (0.062 in.) |
3 mm (0.125 in.) |
6 mm (0.250 in.) |
12 mm (0.500 in.) |
18 mm (0.750 in.) |
25 mm (1.00 in.) |
35 mm (1.50 in.) |
50 mm (2.00 in.) |
ISO |
AISI or C |
| SS321 austenitic |
135-185 |
Annealed |
26 |
85 |
0.033 (0.0013) |
0.041 (0.0016) |
0.050 (0.002) |
0.050 (0.002) |
0.041 (0.0016) |
0.036 (0.0014) |
0.030 (0.0012) |
0.025 (0.001) |
S4, S5, K40, M40 |
M2, M3, C-2 |
| 84 |
275 |
| Speeds and feeds for trepanning deep holes of various steels with high-speed tool steels and carbide tools |
| Material |
Hardness, HB |
Illness |
Speed |
To feed |
Tool material class |
| m/min |
sfm |
mm/rotation |
in./rev |
ISO |
AISI or C |
| Austenitic: SS321 |
135-185 |
Annealed |
20 |
65 |
0.075 |
0.003 |
S4, S5 |
M2, M3 |
| 84 |
275 |
0.15 |
0.006 |
K20 |
C-2 |
| 225-275 |
Cold drawing |
18 |
60 |
0.075 |
0.003 |
S4, S5 |
M2, M3 |
| 69 |
225 |
0.10 |
0.004 |
K20 |
C-2 |
| Nominal speeds for grinding ferrous alloy and carbide threads |
| Material |
Hardness, HB |
Illness |
Thread designation |
ANSI Wheel Identification |
Wheel speed |
Working speed |
| Step, mm |
Threads per 25 mm (1 in.) |
IN |
sfm |
m/min |
sfm |
| Forged austenitic stainless steels: 321, 201, 202, 301, 302, 302B, 304, 304L, 305, 308, 309, 309S, 310, 310S, 314, 316, 316L, 317, 330, 347, 34 8, 3 84, 385 |
135-275 |
Annealed or cold drawn |
6-2.5 |
4-12 |
A90RB |
43 |
8,500 |
1.2 |
4.0 |
| 2-1 |
13-27 |
A120SB |
46 |
9,000 |
| 0.8-0.45 |
28-63 |
A180TB |
48 |
9500 |
| 0.4-0.35 |
64-80 |
A220UB |
51 |
10,000 |
| Recommended speeds and feeds for face milling of ferrous and non-ferrous alloys with high-speed steel and carbide cutters |
| Material |
Hardness, HB |
Illness |
Cutting depth, mm (in.) |
high speed steel tool |
Carbide Tool |
| Uncoated |
Coated |
| Speed |
Feed per tooth, mm (in.) |
Tool material class, ISO (C) |
Speed, m/min (sfm) |
Feed per tooth, mm (in.) |
Tool material class, ISO (C) |
| Speed, m/min (sfm) |
Feed per tooth, mm (in.) |
Tool material, ISO (AISI) |
Soldier, m/min (sfm) |
Indexable, m/min (sfm) |
| Forged Austenitic Stainless Steel 321 |
135-185 HB |
Annealed |
1 (0.040) |
40 (130) |
0.20 (0.008) |
S4, S2 (M2, M7) |
130 (430) |
145 (475) |
0.20 (0.008) |
K10, M20 (C-2) |
215 (700) |
0.20 (0.008) |
CK10, CM20 (CC-2) |
| 4 (0.150) |
30 (100) |
0.30 (0.012) |
S4, S2 (M2, M7) |
100 (325) |
110 (360) |
0.30 (0.012) |
K20, M30 (C-2) |
145 (475) |
0.30 (0.012) |
CK20, CM30 (CC-2) |
| 8 (0.300) |
24 (80) |
0.40 (0.016) |
S4, S2 (M2, M7) |
70 (230) |
85 (280) |
0.40 (0.016) |
K30, M40 (C-2) |
105 (350) |
0.40 (0.016) |
CK30, CM40 (CC-2) |
| Recommended speeds and feeds for milling plates (or flats) of ferrous and non-ferrous alloys with high-speed steel cutters |
| Material |
Hardness, HB |
Illness |
Cutting depth, mm (in.) |
Speed |
Feed per tooth |
High speed steel tool material |
| m/min |
sfm |
mm (in.) |
ISO |
AISI |
| Forged Austenitic Stainless Steel 321 |
135-185 HB |
Annealed |
1 (0.040) |
55 |
180 |
0.15 (0.006) |
S4, S2 |
M2, M7 |
| 4 (0.150) |
43 |
140 |
0.20 (0.008) |
| 8 (0.300) |
34 |
110 |
0.25 (0.010) |
Recommended speeds and feeds for end (peripheral) milling of ferrous and non-ferrous alloys with high-speed steel and carbide
cutters |
| Material |
Hardness, HB |
Illness |
Radial depth of cut, mm (in.) |
high speed steel tool |
Carbide Tool |
| Speed, m/min (sfm) |
Feed, mm/tooth (in./tooth), in cutter diameter of: |
Tool material, ISO (AISI) |
Speed, m/min (sfm) |
Feed, mm/tooth (in./tooth), in cutter diameter of: |
Tool material, ISO (C) |
| 10 mm (0.375 in.) |
12 mm (0.5 in.) |
18 mm (0.75 in.) |
25-50 mm (1-2 in.) |
10 mm (0.375 in.) |
12 mm (0.5 in.) |
18 mm (0.75 in.) |
25-50 mm (1-2 in.) |
| SS321 |
135-185 HB) |
Annealed |
0.5 (0.020) |
34 (110) |
0.025 (0.001) |
0.050 (0.002) |
0.102 (0.004) |
0.13 (0.005) |
S4, S5, S2 (M2, M3, M7) |
110 (360) |
0.013 (0.0005) |
0.025 (0.001) |
0.050 (0.002) |
0.102 (0.004) |
K20, M20 (C-2) |
| 1.5 (0.060) |
24 (80) |
0.050 (0.002) |
0.075 (0.003) |
0.13 (0.005) |
0.15 (0.006) |
82 (270) |
0.025 (0.001) |
0.050 (0.002) |
0.075 (0.003) |
0.13 (0.005) |
diam/4
diam/4 |
21 (70) |
0.025 (0.001) |
0.050 (0.002) |
0.102 (0.004) |
0.13 (0.005) |
72 (235) |
0.025 (0.001) |
0.038 (0.0015) |
0.063 (0.0025) |
0.102 (0.004) |
diam/2
diam/2 |
18 (60) |
0.025 (0.001) |
0.038 (0.0015) |
0.075 (0.003) |
0.102 (0.004) |
67 (220) |
0.013 (0.0005) |
0.025 (0.001) |
0.050 (0.002) |
0.075 (0.003) |
