Tool Steel Hot Hardness Chart
Hot hardness — Rockwell C hardness measured at elevated temperature — for selected high-speed and die steels. The table shows how hardness falls as testing temperature rises, ranking each grade for red hardness in hot-work and high-speed service.
| AISI | Room temperature | 315 °C (600 °F) | 425 °C (800 °F) | 540 °C (1000 °F) | 650 °C (1200 °F) |
|---|---|---|---|---|---|
| High-speed tool steels | |||||
| M1 | 65 | 61 | 58 | 54 | 32 |
| M2 | 65 | 62 | 59 | 55 | 36 |
| M3, classe 1 | 65 | 63 | 60 | 56 | 36 |
| M3, classe 2 | 65 | 63 | 60 | 56 | 36 |
| M4 | 66 | 63 | 60 | 56 | 37 |
| M7 | 65 | 61 | 58 | 54 | 35 |
| M10 | 65 | 60 | 57 | 52 | 33 |
| M30 | 65 | 63 | 58 | 55 | 35 |
| M33 | 65 | 64 | 60 | 57 | 40 |
| M36 | 65 | 64 | 60 | 57 | 40 |
| M42 | 68 | 66 | 65 | 62 | 44 |
| M50 | 64 | 59 | 57 | 52 | — |
| M52 | 64 | 60 | 57 | 53 | — |
| T1 | 65 | 61 | 57 | 53 | 33 |
| T4 | 65 | 61 | 59 | 55 | 38 |
| T5 | 66 | 62 | 60 | 56 | 40 |
| T15 | 68 | 64 | 61 | 57 | 42 |
| Cold-work die steels | |||||
| A2 | 60 | 52 | 46 | 35 | — |
| A8 | 58 | 55 | 52 | 45 | — |
| D2 | 60 | 53 | 47 | 38 | — |
| D4 | 62 | 52 | 46 | 37 | — |
| Hot-work die steels | |||||
| H11 | 54 | 49 | 47 | 42 | 22 |
| H12 | 54 | 49 | 47 | 42 | 22 |
| H13 | 55 | 49 | 47 | 42 | 22 |
| H19 | 54 | 51 | 47 | 42 | 31 |
| H21 | 54 | 52 | 49 | 45 | 29 |
| H23 | 41 | 32 | 30 | 28 | 25 |
| H26 | 58 | 54 | 50 | 46 | 31 |
- (um) Small-diameter bars tested according to the recommended heat treatment.
Notas de mesa
Hot hardness measures hardness at elevated temperature after exposure to that temperature — it is the property behind “red hardness” in high-speed and hot-work tool steels. The 540 °C (1000 °F) and 650 °C (1200 °F) columns rank the grades for hot-work service.
The source table lists A8 at the head of both the cold-work and the hot-work groups; it is shown once here, under cold-work die steels.
Values are comparative hardness test results from the source’s reference 7; small variations between heats and test conditions are normal. Reference data for comparison — verify with the applicable heat-treatment schedule for your part.
Páginas de referência relacionadas
Aço para ferramentas H13 · Aço para ferramentas H11 · Aço para ferramentas H10 · Aço para ferramentas H21 · Aços para ferramentas de trabalho a quente · Tabela de têmpera e revenimento de aços para ferramentas · Tool steel heat treatment guide · Tabela de propriedades do aço ferramenta · Tool steel composition chart · How to select tool steels
Source: ASM Handbook, Volume 1 — Properties and Selection: Irons, Steels, and High-Performance Alloys, Table 14 “Hot hardness of selected high-speed tool steels and die steels” (10th ed.). Reference data for comparison — verify the applicable heat treatment before service.