M33 Molybdenum High Speed Tool Steel (UNS T11333)

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

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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.

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