M42
M42 Grade Introduction:
Molybdenum high-speed steels and tungsten high-speed steels are two types of high-speed tool steels. Molybdenum high-speed steels, also known as group M steels, comprise less initial cost. Molybdenum steel types M1 to M10 have tungsten whereas cobalt is not found in type M6. Cobalt is totally absent in these types of molybdenum high-speed steels.
M42 Grade Application:
- machine materials
- superalloys
- chasers
- broaches
- form and gear cutters
- hobs
- milling cutters
- end mills
M42 Equivalent Grades:
| Country |
USA |
German |
Japan |
| Standard |
ASTM A600 |
DIN EN ISO 4957 |
JIS G4403 |
| Grades |
M42 |
1.3247/HS2-9-1-8 |
SKH59 |
M42 Chemical Composition:
| Element |
C |
Mn |
Si |
Cr |
Ni |
Mo |
W |
V |
Co |
Cu |
P |
S |
| Content (%) |
1.05-1.15 |
0.15-0.40 |
0.15-0.65 |
3.50-4.25 |
0.3 |
9.00-10.00 |
1.15-1.85 |
0.95-1.35 |
7.75-8.75 |
0.25 |
0.03 |
0.03 |
Mechanical Properties:
| Mechanical Properties |
Metric |
Imperial |
| Hardness, Rockwell C (oil quenched from 1204°C, 5 minutes) |
64.3 |
64.3 |
| Hardness, Rockwell C (oil quenched from 1177°C, 5 minutes) |
65.5 |
65.5 |
| Hardness, Rockwell C (oil quenched from 1163°C) |
65.8 |
65.8 |
| Izod impact unnotched (oil quenched at 1191°C; 510°C temper temperature) |
13.6 J |
10.0 ft-lb |
| Izod impact unnotched (oil quenched at 1191°C; 622°C temper temperature) |
24.4 J |
24.4 J |
| Machinability (1% carbon steel) |
35.0 – 40.0% |
35.0 – 40.0% |
| Poisson’s ratio |
0.27-0.30 |
0.27-0.30 |
| Elastic modulus |
190-210 GPa |
27557-30457 ksi |
Physical Properties:
| Physical Properties |
Metric |
Imperial |
| Density |
7.81 g/cm³ |
0.282 lb/in³ |
Thermal Properties:
| Properties |
Unit |
TEMPERATURE °C / °F 20 / 70 |
TEMPERATURE °C / °F 400 / 750 |
TEMPERATURE °C / °F 600 / 1110 |
| Density |
Kg/m³ / lbs/in³ |
8.03 .290 |
7.93 .286 |
7.87 .284 |
| MODULUS OF ELASTICITY |
kN/mm³² psi |
225 33 · 10⁶ |
200 29 · 10⁶ |
180 26 · 10⁶ |
| COEFFICIENT OF THERMAL EXPANSION FROM 20°C / 70°F |
per °C per °F |
— |
11.5 · 10⁻⁶ 6.4 · 10⁻⁶ |
11.8 · 10⁻⁶ 6.6 · 10⁻⁶ |
| Thermal Conductivity |
W/m °C / Btu/sq. ft. h°F/in. |
24 / 166 |
28 / 194 |
27 / 187 |
| Specific Heat |
J/kg °C / Btu/lb °F |
420 / 0.10 |
510 / 0.12 |
600 / 0.14 |
Forging Properties:
Preheat the M42 high-speed steel slowly and uniformly to 650-760°C and equalize. Then increase more quickly to the forging temperature of 1010-1150°C and equalize prior to forging. Do not allow the forging temperature to drop below 980°C, if this occurs reheating will be necessary. Always cool the high-speed steel very slowly after forging.
Stress Relieving:
If tools produced from M42 high-speed steel are heavily machined or ground it is recommended to stress relief after machining and prior to hardening to minimize the possibility of distortion. To stress relieve heat the component to 600-650°C and soak well (approximately two hours) Cool slowly in the furnace. The M42 tools can be finish machined before heat treatment.