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CPM
M4 |
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| Powder
Metal |
CPM M4 high speed steel is an extremely
versatile high speed steel which |
| High
Speed |
provides a unique combination of
high wear resistance with high impact toughness and |
| Tool
Steel |
transverse
bend strength. A large volume of
vanadium carbides provides the high wear |
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resistance. The high impact toughness and high
transverse bend strength are the results of |
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the fine grain size, small carbides,
and superior cleanliness of the powder metallurgy (PM) |
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microstructure. |
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| Typical
Chemistry |
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Carbon |
1.45 |
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Chromium |
4.50 |
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Manganese |
0.25 |
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Vanadium |
3.85 |
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Silicon |
0.25 |
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Molybdenum |
4.50 |
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Sulfur |
0.008 |
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Tungsten |
5.50 |
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| Applications |
CPM M4 is suitable in high speed applications providing improved cutting tool
life compared |
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to conventionally wrought M1, M2,
and M7, and in cold work applications where it provides better |
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toughness and wear resistance than
high-carbon, high-chromium die steels as D2 and D3. |
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| Annealing |
Annealing
must be performed after hot working and before rehardening. Heat at a rate not |
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exceeding
400 F per hour to 1575-1600 F, and hold at temperature for 1 hour per inch of
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maximum thickness; 2 hours
minimum. Then cool slowly with the
furnace at a rate not |
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exceeding
50 F per hour to 1000 F. Continue
cooling to ambient temperature in the furnace or in |
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air. |
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| Heat
Treating |
Preheat
to 1500/1550 F, equalize. A second
reheat at 1850/1900 F is recommended for |
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vacuum hardening. |
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Heat rapidly to the high heat from
the preheat. |
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For Cutting Tools: |
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Soak 5 to 15 minutes. |
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Furnace |
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2150/2200 F |
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Salt Bath: |
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2125/2175 F |
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For Cold Work Tooling: |
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Soak 20 to 45 minutes. |
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Furnace |
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1875/2125 F |
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Salt Bath |
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1850/2100 F |
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Quenching: |
Pressurized gas, warm oil, or
salt. For pressurized gas quenching,
the quench rate |
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to below 1000 F is critical to
obtain the desired properties. |
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For oil, quench until black, about
900 F, then cool in still air to 150/125 F. |
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For salt maintained at 1000/1100 F
equalize in the salt, then cool in still air to 150/125 F. |
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| Tempering |
Temper
immediately after quenching. Typical
temperature range is 1000/1100 F. Do
not |
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temper below 1000 F. Hold at temperature for 2 hours then air
cool to ambient temperature. |
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Double
tempering is required. Triple
tempering is required when austenitized at 2100 F or |
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higher. |
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Note: |
See
your Gateway Metals representative to obtain specific heat treatment |
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information
to obtain certain hardness readings for your specific application. The data |
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presented herein are typical values,
and do not warrant suitability for any specific application or |
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use of this material. Normal variations in the chemical
composition, the size of the product, and |
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heat treatment parameters may result
in different values for the various physical and mechanical |
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properties. |
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