Hot work tool steel
ALTA HM1 Tool Steel Specification
Steel properties
ALTA HM1 steel uses Molybdenum instead of tungsten when design its chemical composition, which greatly reduces the content of tungsten compared to 3Cr2W8V(~AISI H21/DIN 1.2581), this steel's production costs get much reduced. While the amount of chromium and vanadium is appropriately increased. It has excellent thermal fatigue resistance and tempering stability, when maintaining high strength, high thermal stability and high thermal fatigue resistance, meanwhile it can remain good toughness.
HM1 steel has much higher thermal fatigue resistance than 3Cr2W8V/H21/1.2581 steel (see Figure 1).
HM1 steel working temperature is unfavorable exceed 640 °C.
Applications
² Suitable for hot forging dies and forming roll forging dies for presses and bearing rings working under high temperature, high load, rapid heating and cooling conditions
² Precision forging dies for high strength and high heat resistance steel parts
² Die casting dies for aluminum and copper alloys, hot extrusion and other die parts
Chemical composition
Chemical Composition per %
|
C |
Si |
Mn |
P |
S |
Cr |
Mo |
W |
V |
Ni |
Cu |
Min. |
0.32 |
0.60 |
|
|
|
2.80 |
2.50 |
1.20 |
0.80 |
|
|
Max. |
0.42 |
0.90 |
0.65 |
0.020 |
0.010 |
3.30 |
3.00 |
1.80 |
1.20 |
0.25 |
0.25 |
Basic melting process : |
IM/EAF + LF + VD + ESR |
Hardness : |
Max 229 HB (annealed) |
Reduction ratio : |
5 : 1 minimum or required |
Grain size : |
≥ 6.0 per ASTM E112 |
Non-metallic inclusion : |
≤ 1.0 (thick), ≤ 1.5 (thin) per ASTM E45 method A (more pure by ESR route) |
Micro-structure | SEP1614 or NADCA # 207 |
Ultrasonic Test |
SEP1921, EN 10308, ASTM A388 or agreed methods |
Macro-structure |
As per ASTM E381 |
Straightness / flatness |
≤ 1.5 mm / m (machined), ≤ 2.5 mm / m (black) |
Tolerance |
Per discussed |
Size range (round bars) |
Ø 12 - 600 mm |
Size range (flats, plates) |
8 - 500 mm in thickness max. 1100 mm in width |
Heat treatment
Annealing |
Temperature(°C) |
Hardness |
860 - 920 |
max. 229 HB |
Hot-forming |
Temperature(°C) |
900 - 1100 |
Hardening and tempering |
Quenching temperature(°C) |
Quenching medium |
Frequently-used tempering temperature(°C) |
1050 - 1130 |
Oil |
600 - 680 |
**630~650°C tempering x 2h, air-cooled, hardness 51~54HRC
**670~680°C tempering x 2h, air-cooled, hardness 39~42HRC
Ac1 | Ac3 | Ar1 | Ar3 | Ms |
840 | 922 | 786 | 839 | 373 |
Downloads
-
2024-08-02 Alta HM1 SPEC (001 - S3 - T1).pdf
끂28 286.6 KB
Features
² High hot and cold fatigue resistance
² High red hardness
² High hot strength
² Good toughness
² Good wear resistance
² Good hardenability and tempering stability
Figure 1 – Hot and cold fatigue properties of HM1 and 3Cr2W8V
Grade | HRC | Number of cracks | Total depth of cracks/mm | Maximum depth of crack/mm |
HM1 | 45 | 21 | 0.89 | 0.135 |
3Cr2W8V | 47.3 | 8 | 0.56 | 1.34 |
** Test conditions: high frequency induction heating, heating temperature 730~740°C, water cooling, heating 12S, cooling 5S, cycle 630 times.
** GB/T 3Cr2W8V steel is similar as DIN 1.2581, AISI H21 steel
Figure 2 - Relationship between quenching temperature and hardness of HM1 steel
Quenching temperature/°C | 1040 | 1060 | 1080 | 1100 | 1130 | 1150 |
Hardness/HRC | 51.8 | 53.2 | 54 | 55 | 53.5 | 52.8 |
Mechanical properties:
Figure 3 - Impact toughness after 600°C tempering at different quenching temperatures
Quenching temperature/°C | 950 | 1000 | 1030 | 1050 | 1060 | 1090 | 1120 | |
Tempering temperature/°C | 600°C x 1.5h x 2 times, air-cooled | |||||||
Ak/(J/cm2) | longitudinal | 37 | 37 | 37 | 35 | 40 | 33 | 31 |
crosswise | / | / | 15 | 25 | 16 | / | / |
Figure 4 - Impact toughness and fracture toughness at room temperature and high temperature
Grades | Hardness (HRC) | Impact toughness |
Room fracture toughness KIC(MPa√m) |
||||
Room 20°C |
300°C | 600°C | 650°C | 700°C | |||
HM1 | 48~48.3 | 12.3 | 19.9 | 28.4 | 29.2 | 27.4 | 29.5 |
3Cr2W8V | 48.8~49.1 | 13.0 | 21.3 | 25.0 | 27.4 | 26.1 | 32.7 |
Coefficient of thermal conductivity : λ W/(m·K)
Temperature °C | 100 | 400 | 480 | 570 | 670 |
λ | 31.8 | 30.9 | 31.8 | 31.8 | 31.8 |
Coefficient of linear expansion : α(mm/(mm·°C))
Temperature °C | 20~100 | 20~200 | 20~300 | 20~400 | 20~500 | 20~600 | 20~700 |
Αx 10-6 | 10.40 | 12.80 | 12.90 | 12.80 | 12.70 | 12.30 | 12.70 |
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