Oct 25 2012
Topics Covered
Introduction
Chemical Composition
Physical Properties
Mechanical Properties
Thermal Properties
Other Designations
Fabrication and Heat Treatment
Forming
Welding
Machinability
Forging
Heat Treatment
Annealing
Cold Working
Tempering
Hardening
Hot Working
Applications
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, have less initial cost. Molybdenum steel types
M1 to M10, except M6, have tungsten, but cobalt is not found in these
type of steels.
M33 molybdenum high speed tool steel (UNS T11333) comprises a medium
amount of carbon and chromium along with tungsten that together
enhances the strength of M33 molybdenum high speed tool steel. This
high speed tool steel in comparison with tungsten high speed tool
steels has much enhanced toughness and is less expensive though it is
quite similar to the tungsten high speed tool steels.
Chemical Composition
The chemical composition of M33 molybdenum high speed tool steel is
outlined in the following table.
| Element |
Content
(%) |
Fe
|
Balance
|
| C |
0.85-0.92 |
| Mn |
0.15-0.40 |
| Si |
0.15-0.50 |
| Cr |
3.50-4.00 |
| Ni |
0.3 |
| Mo |
9.00-10.00 |
| W |
1.30-2.10 |
| V |
1.00-1.35 |
| Co |
7.75-8.75 |
| Cu |
0.25 |
| P |
0.03 |
| S |
0.03 |
Physical Properties
The table below shows the physical properties of M33 molybdenum high
speed tool steel.
| Physical
properties |
Metric |
Imperial |
| Melting point |
1427°C |
2601°F |
Mechanical Properties
The mechanical properties of M33 molybdenum high speed tool steel
are displayed in the following table.
| Mechanical
properties |
Metric |
Imperial |
| Poisson's ratio |
0.27-0.30 |
0.27-0.30 |
| Elastic modulus |
190-210 GPa |
27557-30458 ksi |
Thermal Properties
The table below outlines the thermal properties of M33 molybdenum
high speed tool steel.
| Properties |
Conditions |
| T
(°C) |
Treatment |
| Thermal expansion |
11 x 10-6/ºC |
20-425 |
- |
Other Designations
Equivalent materials to M33 molybdenum high speed tool steel are:
- DIN 1.3249
- B.S. BM 34
- ASTM A600
- FED QQ-T-590
- UNS T11333
Fabrication and Heat Treatment
Forming
Conventional methods are used for forming of M33 molybdenum high
speed tool steel.
Welding
M33 molybdenum high speed tool steel is weldable.
Machinability
M33 tool steel has medium machinability that is rated at 55% to 60%.
Forging
M33 tool steel is forged at 1121°C (2049°F) down to 954°C (1749°F).
It has been recommended that forging below 927°C (1700°F) should not be
carried out for M33 tool steel.
Heat Treatment
M33 tool steel is preheated to 787.8 °C (1450°F) and rapidly heated
to 1204-1232°C (2199-2249°F). It is then held for 2 to 5 minutes. Salt
bath, air quenching or oil can be used for heat treatment of M33 tool
steel.
Annealing
Annealing for M33 tool steel takes place at 885°C (1625°F) and this
is followed by cooling the steel slowly in a furnace at less than 4°C
for an hour.
Cold Working
Conventional methods are followed for cold working of M33 tool steel.
Tempering
M33 too steel is tempered at 538 °C to 593°C (1000.4°F - 1099.4°F)
for Rockwell C of 65 to 60. The tempering process is repeated to obtain
better results.
Hardening
Tempering and heat treatment process details are applied for the
hardening of M33 tool steel.
Hot Working
This process is carried out by consulting the supplier for lower
temperature working information besides referring to the forging data.
Applications
M33 molybdenum high speed tool steel is used for all varieties of
cutting tools.