Steel Machinability Rating Chart
Machinability ratings for plain carbon, free-cutting and alloy steels on the 1212 steel basis, where 1212 is set at 100 and every other grade is expressed as a percentage of the cutting speed it allows. The hardness range the rating was measured at travels with each grade, because machinability follows hardness more than it follows the grade number.
1212 = 100 rating basis
140 rating, cutting speed as a percentage of 1212 steel
179-235 hardness range at which the rating applies
(b) footnote
Plain carbon steels
Ratings on the 1212 steel basis, where 1212 is set at 100. Table 4 of the source.
| SAE/AISI grade | Machinability rating | Hardness, HB |
|---|---|---|
| 1212 | 100 | 175 |
| 1005 | 45 | 95 |
| 1006 | 50 | 95 |
| 1010 | 55 | 105 |
| 1015 | 60 | 111 |
| 1017 | 65 | 116 |
| 1019 | 70 | 131 |
| 1030 | 70 | 149 |
| 1038 | 65 | 163 |
| 1040 | 60 | 170 |
| 1045 | 55 | 179 |
| 1045 | 60 | 170 |
| 1050 | 45 | 197 |
| 1050 | 55 | 189 |
| 1065 | 60 | 183 |
| 1070 | 55 | 187 |
| 1075 | 48 | 192 |
| 1085 | 45 | 192 |
| 1095 | 45 | 197 |
| 1524 | 60 | 163 |
| 1536 | 55 | 187 |
| 1541 | 45 | 207 |
| 1547 | 40 | 207 |
| 1547 | 45 | 187 |
Source: ASM Handbook, Vol 1 (10th ed.), “Machinability of Steels”, Table 4.
Steel machinability ratings chart, printable PDF
Two A4 pages with the plain carbon, free-cutting and alloy steel tables, the hardness range each rating was measured at, and our contact details.
Free-cutting resulfurized and rephosphorized steels
Cutting speed as a percentage of the speed used on 1212 steel. Table 5 of the source.
| Grade | Machinability rating, % | Hardness, HB |
|---|---|---|
| 1117 | 90 | 137 |
| 1118 | 85 | 143 |
| 1137 | 70 | 197 |
| 1140 | 70 | 170 |
| 1141 | 70 | 212 |
| 1144 | 80 | 217 |
| 1146 | 70 | 187 |
| 1151 | 65 | 207 |
| 1212 | 100 | — |
| 1213 | 136 | — |
| 1215 | 136 | — |
| 12L14 | 160 | 163 |
| 12L14 | 190 | 137 |
| 12L14 | 235 | 137 |
| 12L14 | 295 | 137 |
Source: ASM Handbook, Vol 1 (10th ed.), “Machinability of Steels”, Table 5.
Alloy steels
Ratings for the through-hardening alloy grades, again against 1212 steel at 100. Table 6 of the source.
| Grade | Machinability rating | Hardness, HB |
|---|---|---|
| 1330 | 55 | 179–235 |
| 1340 | 50 | 183–241 |
| 1345 | 45 | 183–241 |
| 4024 | 75 | 156–207 |
| 4028 | 75 | 167–212 |
| 4042 | 65 | 179–229 |
| 4130 | 70 | 187–229 |
| 4140 | 65 | 187–229 |
| 41L40 | 85 | 185–230 |
| 4150 | 55 | 187–240 |
| 4340 | 50 | 187–240 |
| 4620 | 65 | 183–229 |
| 50B40 | 65 | 174–223 |
| 50B60 | 55 | 170–212 |
| 5130 | 70 | 174–212 |
| 5140 | 65 | 179–217 |
| 5160 | 55 | 179–217 |
| 51B60 | 55 | 179–217 |
| 50100 | 40 | 183–240 |
| 51100 | 40 | 183–240 |
| 52100 | 40 | 183–240 |
| 8115 | 65 | 163–202 |
| 81B45 | 65 | 179–223 |
| 8630 | 70 | 179–229 |
| 8620 | 65 | 179–235 |
| 86L20 | 85 | — |
| 8660 | 55 | 179–217 |
| 8645 | 65 | 184–217 |
| 86B45 | 65 | 184–217 |
| 8740 | 65 | 184–217 |
Source: ASM Handbook, Vol 1 (10th ed.), “Machinability of Steels”, Table 6.
Steel machinability ratings chart, printable PDF
Two A4 pages with the plain carbon, free-cutting and alloy steel tables, the hardness range each rating was measured at, and our contact details.
- (a) The machinability rating of 1212 steel is assigned at 100, and the ratings of the other grades are percentages of its cutting speed at the same tool life.
- (b) The hardness shown is the range the grade is normally supplied in, not a single value. Ratings measured outside that range do not transfer.
- (c) A rating is a shop comparison, not a specification. Tool material, tool geometry, coolant, rigidity and surface finish requirement all move the achievable cutting speed by more than the gaps between neighbouring grades in these tables.
Table notes
The two tables use slightly different bases and are printed here as the source gives them. Table 5 is a cutting speed percentage against 1212 steel, while Tables 4 and 6 are ratings on the same 1212 basis. Do not read a number from one table against a number from another without checking which basis it uses. Some grades appear more than once because the rating is quoted for more than one condition, and the hardness column tells those rows apart.
Hardness is the supplied condition of the bar. A prehardened or cold-drawn item moves down the table, and an annealed item moves up it. Confirm the delivery hardness with the material test certificate or ask Aobo Steel for the condition that suits the part.
Composition data is for general reference only. Actual values vary by standard, mill, and heat number. Confirm against the material test certificate (MTC) or contact Aobo Steel.
Machinability is bought with sulfur
The 12xx series sits at the top of these tables because sulfur is raised on purpose. The carbon steel composition chart shows the sulfur column that does it.
Where tool steel sits on this scale
Tool steel uses the same kind of rating on a different basis, so the two charts are read separately. See the tool steel machinability ratings for that scale.
Rating against the part, not the grade
A 4140 part at 28 HRC and the same part at 34 HRC do not machine alike. The hardness the grade is normally supplied in is mapped on the 4140 properties page.
Related reference pages
Carbon steel composition chart · Alloy steel composition chart · Tool steel machinability ratings · Tool steel processing characteristics · Tap drill size chart · 4140 steel properties · H steel composition chart
Source: ASM Handbook, Vol 1 (10th ed.), “Machinability of Steels”, Tables 4, 5 and 6. Ratings are percentages of the cutting speed of 1212 steel at equal tool life.