SteelWhat is M4 steel and what is it used for? High-speed steel (HSS)
M4 steel is a high-speed steel (HSS). In this guide we explain what M4 steel is, its chemical composition, hardness, how it is heat treated, what it is used for and the sizes we stock.
What is M4 steel?
Molybdenum-tungsten-vanadium high-speed steel (HSS) that retains its hardness and edge at the high temperatures of high-speed cutting. For long-life cutting tools subject to heavy abrasive wear.
Chemical composition of M4 steel
This is the typical composition of M4 steel (AISI M4 / EN-DIN 1.3351 / JIS SKH54 standard):
| Element | Contents | What for? |
|---|---|---|
| Carbon (C) | 1.25 – 1.40 % | Hardness and wear resistance |
| Silicon (Si) | 0.20 – 0.45 % | Deoxidizer |
| Manganese (Mn) | 0.15 – 0.40 % | Hardenability |
| Chromium (Cr) | 3.75 – 4.75 % | Hardenability and wear resistance |
| Molybdenum (Mo) | 4.25 – 5.50 % | Hot hardness and hardenability |
| Tungsten (W) | 5.25 – 6.50 % | Forms very hard carbides (cutting and wear) |
| Vanadium (V) | 3.75 – 4.50 % | Refines the grain and forms hard carbides |
| Phosphorus (P) | 0.030 % max. | Impurity, kept low |
| Sulfur (S) | 0.030 % max. | Impurity, kept low |
Hardness and heat treatment of M4 steel
The typical working hardness of M4 is 62 – 65 HRC. It is a high-speed steel with more vanadium than M2, which gives it superior abrasive wear resistance. It requires high-temperature quenching and several temperings, and retains its hardness when hot. You can see the full overview in our article on heat treatments for steel, and hardness scales in steel hardness.
What is it for? Applications of M4
M4 steel is mainly used in:
- Industrial drill bits
- Taps for threading
- Milling cutters
- Precision reamers
- Cutting broaches
- Gear cutters
- Lathe tools
- Form cutters
- Heading dies
Forms and sizes we carry
At NAT MAC we stock M4 steel in these forms and sizes:
| Package size | Sizes |
|---|---|
| Round bars | Ø 1/2" – 4" (Ø 13 – 102 mm) |
| Plates | 3/8" – 2" (10 – 51 mm) |
If you need a particular size, tell us which one and we will gladly source it for you.
M4 equivalents and standards
M4 steel is also identified by these standards: AISI M4 / EN-DIN 1.3351 / JIS SKH54. You can see how to read them in our article on steel standards.
In summary
- M4 is a high-speed steel (HSS)
- Typical composition: C 1.25 – 1.40 and Cr 3.75 – 4.75, plus alloying elements
- Typical working hardness: 62 – 65 HRC
- Ideal for long-life cutting with high abrasive wear
- We carry it in round bar (1/2" – 4") and plates (3/8" – 2"), cut to size
Why buy your M4 steel at NAT MAC?
We have more than 54 years of experience as an industrial supplier and ISO 9001 certified quality. We carry a wide range of tool grade steels and help you choose the right one for your tool or mold.
- Quality M4 Steel, backed and traceable
- Material cut to the size you need
- Technical advice on choosing the right grade
- Wide range of tool-grade steels in stock
- On-time deliveries and competitive prices
Tell us what tool or mold you are going to make and in what dimensions, and we will recommend the right grade and form. Request your free quote.
Sources: data sheet from our NAT MAC catalog (composition, sizes and applications) and public industry references for working hardness. Values are for reference and may vary by standard, heat and treatment.
