Tool Steel Density and Thermal Expansion Chart
Density and mean thermal expansion for 57 tool steels — water-, shock-, oil-, air-hardening, cold-work (D), hot-work (H), high-speed (T, M), special-purpose (L) and mold (P) types. Both metric (g/cm³, µm/m·K) and imperial (lb/in.³, µin./in.·°F) values are listed, for die and tooling design that involves thermal growth or weight.
| Type | Density g/cm³ | Density lb/in.³ | µm/m·K 20→100 °C | µm/m·K →200 °C | µm/m·K →425 °C | µm/m·K →540 °C | µm/m·K →650 °C | µin./in.·°F 70→200 °F | µin./in.·°F →400 °F | µin./in.·°F →800 °F | µin./in.·°F →1000 °F | µin./in.·°F →1200 °F |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| W1 | 7.84 | 0.282 | 10.4 | 11.0 | 13.1 | 13.8(a) | 14.2(b) | 5.76 | 6.13 | 7.28 | 7.64(a) | 7.90(b) |
| W2 | 7.85 | 0.283 | — | — | 14.4 | 14.8 | 14.9 | — | — | 8.0 | 8.2 | 8.3 |
| S1 | 7.88 | 0.285• | 12.4 | 12.6 | 13.5 | 13.9 | 14.2 | 6.9 | 7.0 | 7.5 | 7.7 | 7.9 |
| S2 | 7.79 | 0.281 | 10.9 | 11.9 | 13.5 | 14.0 | 14.2 | 6.0 | 6.6 | 7.5 | 7.8 | 7.9 |
| S5 | 7.76 | 0.280 | — | — | 12.6 | 13.3 | 13.7 | — | — | 7.0 | 7.4 | 7.6 |
| S6 | 7.75 | 0.279 | — | — | 12.6 | 13.3 | — | — | — | 7.0 | 7.4 | — |
| S7 | 7.76 | 0.280 | — | 12.6 | 13.3 | 13.7(a) | 13.3 | — | 7.0 | 7.4 | 7.6(a) | 7.4 |
| O1 | 7.85 | 0.283 | — | 10.6(c) | 12.8 | 14.0(d) | 14.4(d) | — | 5.9(c) | 7.1 | 7.8(d) | 8.0(d) |
| O2 | 7.66 | 0.277 | 11.2 | 12.6 | 13.9 | 14.6 | 15.1 | 6.2 | 7.0 | 7.7 | 8.1 | 8.4 |
| O6 | 7.70 | 0.277 | — | 11.2 | 12.6 | 12.9 | 13.7 | — | 6.2 | 7.0 | 7.2 | 7.6 |
| O7 | 7.8 | 0.282 | — | — | — | — | — | — | — | — | — | — |
| A2 | 7.86 | 0.284 | 10.7 | 10.6(c) | 12.9 | 14.0 | 14.2 | 5.96 | 5.9(c) | 7.2 | 7.8 | 7.9 |
| A6 | 7.84 | 0.283 | 11.5 | 12.4 | 13.5 | 13.9 | 14.2 | 6.4 | 6.9 | 7.5 | 7.7 | 7.9 |
| A7 | 7.66 | 0.277 | — | — | 12.4 | 12.9 | 13.5 | — | — | 6.9 | 7.2 | 7.5 |
| A8 | 7.87 | 0.284 | — | — | 12.0 | 12.4 | 12.6 | — | — | 6.7 | 6.9 | 7.0 |
| A9 | 7.78 | 0.281 | — | — | 12.0 | 12.4 | 12.6 | — | — | 6.7 | 6.9 | 7.0 |
| A10 | 7.68 | 0.278 | 12.8 | 13.3 | — | — | — | 7.1 | 7.4 | — | — | — |
| D2 | 7.70 | 0.278 | 10.4 | 10.3 | 11.9 | 12.2 | 12.2 | 5.8 | 5.7 | 6.6 | 6.8 | 6.8 |
| D3 | 7.70 | 0.278 | 12.0 | 11.7 | 12.9 | 13.1 | 13.5 | 6.7 | 6.5 | 7.2 | 7.3 | 7.5 |
| D4 | 7.70 | 0.278 | — | — | 12.4 | — | — | — | — | 6.9 | — | — |
| D5 | — | — | — | — | — | 12.0 | — | — | — | — | — | 6.7 |
| H10 | 7.81 | 0.281 | — | — | 12.2 | 13.3 | 13.7 | — | — | 6.8 | 7.4 | 7.6 |
| H11 | 7.75 | 0.280 | 11.9 | 12.4 | 12.8 | 12.9 | 13.3 | 6.6 | 6.9 | 7.1 | 7.2 | 7.4 |
| H13 | 7.76 | 0.280 | 10.4 | 11.5 | 12.2 | 12.4 | 13.1 | 5.8 | 6.4 | 6.8 | 6.9 | 7.3 |
| H14 | 7.89 | 0.285 | 11.0 | — | — | — | — | 6.1 | — | — | — | — |
| H19 | 7.98 | 0.288 | 11.0 | 11.0 | 12.0 | 12.4 | 12.9 | 6.1 | 6.1 | 6.7 | 6.9 | 7.2 |
| H21 | 8.28 | 0.299 | 12.4 | 12.6 | 12.9 | 13.5 | 13.9 | 6.9 | 7.0 | 7.2 | 7.5 | 7.7 |
| H22 | 8.36 | 0.302 | 11.0 | — | 11.5 | 12.0 | 12.4 | 6.1 | — | 6.4 | 6.7 | 6.9 |
| H26 | 8.67 | 0.313 | — | — | — | 12.4 | — | — | — | — | 6.9 | — |
| H42 | 8.15 | 0.295 | — | — | — | 11.9 | — | — | — | — | 6.6 | — |
| T1 | 8.67 | 0.313 | — | 9.7 | 11.2 | 11.7 | 11.9 | — | 5.4 | 6.2 | 6.5 | 6.6 |
| T2 | 8.67 | 0.313 | — | — | — | — | — | — | — | — | — | — |
| T4 | 8.68 | 0.313 | — | — | — | 11.9 | — | — | — | — | 6.6 | — |
| T5 | 8.75 | 0.316 | 11.2 | — | — | 11.5 | — | 6.2 | — | — | 6.4 | — |
| T6 | 8.89 | 0.321 | — | — | — | — | — | — | — | — | — | — |
| T8 | 8.43 | 0.305 | — | — | — | — | — | — | — | — | — | — |
| T15 | 8.19 | 0.296 | — | 9.9 | 11.0 | 11.5 | — | — | 5.5(c) | 6.1 | 6.4 | — |
| M1 | 7.89 | 0.285 | — | 10.6(c) | 11.3 | 12.0 | 12.4 | — | 5.9(c) | 6.3 | 6.7 | 6.9 |
| M2 | 8.16 | 0.295 | 10.1 | 9.4(c) | 11.2 | 11.9 | 12.2 | 5.6 | 5.2(c) | 6.2 | 6.6 | 6.8 |
| M3, class 1 | 8.15 | 0.295 | — | — | 11.5 | 12.0 | 12.2 | — | — | 6.4 | 6.7 | 6.8 |
| M3, class 2 | 8.16 | 0.295 | — | — | 11.5 | 12.0 | 12.8 | — | — | 6.4 | 6.7 | 7.1 |
| M4 | 7.97 | 0.288 | — | 9.5(c) | 11.2 | 12.0 | 12.2 | — | 5.3(c) | 6.2 | 6.7 | 6.8 |
| M7 | 7.95 | 0.287 | — | 9.5(c) | 11.5 | 12.2 | 12.4 | — | 5.3(c) | 6.4 | 6.8 | 6.9 |
| M10 | 7.88 | 0.285• | — | — | 11.0 | 11.9 | 12.4 | — | — | 6.1 | 6.6 | 6.9 |
| M30 | 8.01 | 0.289 | — | — | 11.2 | 11.7 | 12.2 | — | — | 6.2 | 6.5 | 6.8 |
| M33 | 8.03 | 0.290 | — | — | 11.0 | 11.7 | 12.0 | — | — | 6.1 | 6.5 | 6.7 |
| M36 | 8.18 | 0.296 | — | — | — | — | — | — | — | — | — | — |
| M41 | 8.17 | 0.295 | — | 9.7 | 10.4 | 11.2 | — | — | 5.4 | 5.8 | 6.2 | — |
| M42 | 7.98 | 0.288 | — | — | — | — | — | — | — | — | — | — |
| M46 | 7.83 | 0.283 | — | — | — | — | — | — | — | — | — | — |
| M47 | 7.96 | 0.288 | 10.6 | 11.0 | 11.9 | — | 12.6 | 5.9 | 6.1 | 6.6 | — | 7.0 |
| L2 | 7.86 | 0.284 | — | — | 14.4 | 14.6 | 14.8 | — | — | 8.0 | 8.1 | 8.2 |
| L6 | 7.86 | 0.284 | 11.3 | 12.6 | 12.6 | 13.5 | 13.7 | 6.3 | 7.0 | 7.0 | 7.5 | 7.6 |
| P2 | 7.86 | 0.284 | — | — | 13.7 | — | — | — | — | 7.6 | — | — |
| P5 | 7.80 | 0.282 | — | — | — | — | — | — | — | — | — | — |
| P6 | 7.85 | 0.284 | — | — | — | — | — | — | — | — | — | — |
| P20 | 7.85 | 0.284 | — | — | 12.8 | 13.7 | 14.2 | — | — | 7.1 | 7.6 | 7.9 |
- (a) From 20 °C to 500 °C (70 °F to 930 °F).
- (b) From 20 °C to 600 °C (70 °F to 1110 °F).
- (c) From 20 °C to 260 °C (70 °F to 500 °F).
- (d) From 40 °C (100 °F).
Table notes
Density is given at room temperature. Thermal expansion is the mean coefficient between the base temperature (20 °C / 70 °F unless marked with a footnote) and the temperature shown in the column heading.
Dashes indicate values not given in the source table.
• Source correction: the source prints 0.255 lb/in.³ for S1 and M10, which is inconsistent with 7.88 g/cm³ (0.285 lb/in.³). The tabulated 0.285 value is shown here; the original figure is noted for traceability.
Note: footnote (d) is printed in the source as “From 40 ° (100 °F)” with the degree unit missing; it is shown here as 40 °C (100 °F).
The low-expansion cold-work grades (D2/D3, H13, M-series) sit near 10.4–12.4 µm/m·K, while the high-carbon water- and oil-hardening grades and L2 reach 13–15 µm/m·K — relevant when sizing dies, fixtures and tooling that see service heat. Verify against the applicable heat treatment before design use.
Related reference pages
D2 tool steel · D3 tool steel · O1 tool steel · H13 tool steel · H11 tool steel · H10 tool steel · S7 tool steel · M2 tool steel · Tool steel properties chart · Tool steel hot hardness chart · Tool steel hardening and tempering chart · Hot-work tool steel softening resistance · Tool steel thermal conductivity chart
Source: ASM Handbook, Volume 1 — Properties and Selection: Irons, Steels, and High-Performance Alloys, Table 11 “Density and thermal expansion of selected tool steels” (10th ed., pp. 1814–1817). Reference data for comparison — verify the applicable heat treatment before design use.