Tool Steel Grades No Longer in Common Use, Compositions
Tool steel grades go out of use for the ordinary commercial reasons. Demand for a type falls, the mills stop rolling it, and the AISI keeps the designation for years after the last heat. That matters in two situations. A drawing written in the 1980s may still name a grade nobody sells, and a tool that arrives for repair may be marked with one. This page lists the compositions of the tool steels that are no longer in common use, grouped the way the source groups them, so the grade named on an old drawing can be placed against what is available now.
What the table covers
The table runs across the tool steel families rather than one of them: high speed, hot work, cold work, shock resisting, mold, special purpose and water hardening all appear in it, because a grade can fall out of use in any of them. The composition columns are the same ones used for the grades still in production, so a row here can be read directly against the tables for the current grades. Where a value is printed as a dash the source lists nothing for that element, and where the Others column carries an element the rest of that row does not, it is printed there.
| Type | C | W | Mo | Cr | V | Others |
|---|---|---|---|---|---|---|
| High-speed steels | ||||||
| M6 | 0.80 | 4.25 | 5.00 | 4.00 | 1.50 | 12.00 Co |
| M8 | 0.80 | 5.00 | 5.00 | 4.00 | 1.50 | 1.25 Nb |
| M15 | 1.50 | 6.50 | 3.50 | 4.00 | 5.00 | 5.00 Co |
| M45 | 1.25 | 8.00 | 5.00 | 4.25 | 1.60 | 5.50 Co |
| T3 | 1.05 | 18.00 | — | 4.00 | 3.00 | — |
| T7 | 0.75 | 14.00 | — | 4.00 | 2.00 | — |
| T9 | 1.20 | 18.00 | — | 4.00 | 4.00 | — |
| Hot-work steels | ||||||
| H15 | 0.40 | — | 5.00 | 5.00 | — | — |
| H16 | 0.55 | 7.00 | — | 7.00 | — | — |
| H20 | 0.35 | 9.00 | — | 2.00 | — | — |
| H41 | 0.65 | 1.50 | 8.00 | 4.00 | 1.00 | — |
| H43 | 0.55 | — | 8.00 | 4.00 | 2.00 | — |
| Cold-work steels | ||||||
| D1 | 1.00 | — | 1.00 | 12.00 | — | — |
| D6 (a) | — | — | — | — | — | — |
| A5 | 1.00 | — | 1.00 | 1.00 | — | 3.00 Mn |
| Shock-resisting steels | ||||||
| S3 | 0.50 | 1.00 | — | 0.74 | — | — |
| S4 | 0.55 | — | — | — | — | 2.00 Si, 0.80 Mn |
| Mold steel | ||||||
| P1 | 0.10 | — | — | — | — | — |
| Special-purpose steels | ||||||
| L1 | 1.00 | — | — | 1.25 | — | — |
| L3 | 1.00 | — | — | 1.50 | 0.20 | — |
| L4 | 1.00 | — | — | 1.50 | 0.25 | 0.60 Mn |
| L5 | 1.00 | — | 0.25 | 1.00 | — | 1.00 Mn |
| L7 | 1.00 | — | 0.40 | 1.40 | — | 0.35 Mn |
| F1 | 1.00 | 1.25 | — | — | — | — |
| F2 | 1.25 | 3.50 | — | — | — | — |
| F3 | 1.25 | 3.50 | — | 0.75 | — | — |
| Water-hardening tool steels | ||||||
| W3 | 1.00 | — | — | — | 0.50 | — |
| W4 | 0.60/1.40 (b) | — | — | 0.25 | — | — |
| W6 | 1.00 | — | — | 0.25 | 0.25 | — |
| W7 | 1.00 | — | — | 0.50 | 0.20 | — |
Source, ASM Handbook Vol.1, article Wrought Tool Steels, Table 3. Source footnotes, (a) D6 is now included with D3 in Table 1, so the source prints the grade with no separate composition for it, (b) various carbon contents were available for W4. A dash means the source lists no value.
The grades most often found on old drawings
Four of these turn up often enough to be worth naming. T3, T7 and T9 are the tungsten high speed steels between T1 and T15, and they sit in the same family as the T1 and T15 that are still sold, so a drawing calling for T3 is usually satisfied by a current tungsten grade or by the molybdenum equivalent depending on the application. H20 and H15 are hot work grades from before the chromium hot work series settled on H11, H12 and H13, and both are higher in tungsten than anything made today. D1 is the 12 per cent chromium cold work grade that D2 and D3 largely displaced, and D6 has been folded into D3 altogether. F1, F2 and F3 are the carbon tungsten special purpose grades, and their nearest current equivalent is a water hardening grade with more alloy.
Substituting for a grade that is no longer made
A discontinued grade is not usually replaced by a chemical match, because there is no match. The useful approach is to work back to the property the drawing was written for, and then pick from the grades that are available. In the tungsten high speed family the substitution is normally made on hot hardness, and the current tungsten grades or the cobalt molybdenum grades cover the same range. In hot work the substitution is made on the working hardness and on thermal fatigue resistance. In cold work the substitution is made on wear resistance at a given hardness, which is where the current D series and the P/M cold work grades sit. Two things stay true in every case: the hardness on the drawing is the hardness the tool was designed for and should be matched rather than exceeded, and the heat treatment cycle has to be taken from the grade actually supplied rather than from the old drawing.
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.
Where to go next
The compositions of the grades that are still made are on the tool steel composition chart, and the properties of the L and S groups, both of which lost grades to this list, are on the L series and S series properties page. The properties that decide a substitution are collected on the tool steel properties chart. Aobo Steel will quote a current equivalent against a drawing that names a discontinued grade.
Source: ASM Handbook, Vol 1, Properties and Selection: Irons, Steels and High-Performance Alloys.