AISI M7 / 1.3348 / DIN S2-9-2
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Specification, Chemical & Mechanical Performance
Designation by Standards
| Brand Name | Ravne No. | Mat. No. | DIN | EN | AISI |
| BR885 | 885 | 1.3348 | S2-9-2 | HS2-9-2 | M7 |
Chemical Composition (in weight %)
| C | Si | Mn | Cr | Mo | Ni | V | W | Others |
| 0.98 | max. 0.70 | max. 0.40 | 4.00 | 8.70 | - | 1.95 | 1.80 | - |
Description
M7 is one of the High Speed Tool Steels in the molybdenum alloy family, with tungsten, chromium and vanadium for strengthening. It has good hardenability and is very wear resistant. Very high resistance to softening at elevated temperatures and good toughness. Deep hardening response.
Applications
M7 is widely used for cutting tools in machining operations. Sendzimir rolls, segment and circular cutters, profile cutting tools, thread cutting drills and cold forming tools.
Physical properties (avarage values) at ambient temperature
Modulus of elasticity [103 x N/mm2]: 217
Density [g/cm3]: 8.30
Thermal conductivity [W/m.K]: 19.0
Electric resistivity [Ohm mm2/m]: 0.65
Specific heat capacity[J/g.K]: 0.46
Coefficient of Linear Thermal Expansion 10-6 oC-1
| 20-100oC | 20-200oC | 20-300oC | 20-400oC | 20-500oC | 20-600oC | 20-700oC |
| 11.7 | 12.5 | 12.9 | 13.2 | 13.4 | 13.4 | 13.4 |
Continuous Cooling Transformation (CCT) Diagram
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Time-Temperature Transformation (TTT) Diagram
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Soft Annealing
Heat to 820-880oC, cool slowly in furnace. This will produce a maximum Brinell hardness of 230-280.
Hardening
Heat up to 450-600oC, preheat to 850oC and then to 1050oC. Harden from a temperature of 1180-1220oC followed by oil, air quenching or warm bath at 550oC. Hardness after quenching is 64-66 HRC.
Tempering
Tempering temperature: 3 x 1 hour at 540-560oC. Hardness after tempering is min 64 HRC.
Forging
Hot forming temperature: 1100-900oC.
Cold Working: In the annealed condition M7 may be cold worked by conventional methods.
Machinability
Machinability is medium, rating about 60% that of the W group water hardening low alloy tool steels at 100% for comparison.
Corrosion Resistance
Although this alloy contains chromium and molybdenum it is still a steel and thus will corrode. It should be protected from rusting.
Welding
This is a complex alloy but is weldable. Consult the supplier for procedures and details.
Forms manufactured: Please see the Dimensional Sales Program.
Disclaimer
The information and data presented herein are typical or average values and are not a guarantee of maximum or minimum values. Applications specifically suggested for material described herein are made solely for the purpose of illustration to enable the reader to make his own evaluation and are not intended as warranties, either express or implied, of fitness for these or other puposes. There is no representation that the recipient of this literature will receive updated editions as the become available.
