S45C carbon steel / AISI 1045
Tough medium-carbon steel used for axes, working tools and structural components where strength, impact resistance and heat-treatability are important.
S45C and AISI 1045 are closely related grades of unalloyed medium-carbon steel with approximately 0.45% carbon. The designation S45C comes from the Japanese JIS standard, while 1045 is used in the American AISI/SAE system.
Both steels offer a balanced combination of hardness, strength, toughness and ease of machining. After proper heat treatment, they can form a durable working edge and are therefore used, for example, for axes, hammers, chisels, shafts, gears and other highly stressed components.
In Japanese axes, S45C may also appear as the cutting section in a traditional Warikomi construction. In this method, the harder edge steel is forge-welded into a softer material that helps the entire head withstand impacts more effectively.
#ShowMore#
Approximately 0.45% carbon
The higher carbon content compared with common structural steels allows the steel to be effectively heat-treated.
Good toughness
A suitably selected hardness provides the resistance required for axes and other impact-loaded tools.
Easier sharpening
The working edge can usually be restored with standard sharpening stones or diamond abrasives.
Requires protection
The steel is not stainless and therefore must be cleaned, thoroughly dried and lightly oiled after use.
Are S45C and AISI 1045 the same steels?
S45C and AISI 1045 are very similar in chemical composition and properties and are often listed as equivalents in commercial materials. From a standards perspective, however, they are not completely identical grades.
They differ mainly in the limit values for carbon, phosphorus, sulfur and certain other elements. For common working tools they are generally referred to together as S45C / AISI 1045. For precise industrial or safety-critical applications, however, the specific standard and material certificate would need to be verified.
| Property | S45C | AISI 1045 |
|---|---|---|
| Standard system | Japanese JIS | American AISI/SAE |
| Carbon content | Approximately 0.42–0.48% | Approximately 0.43–0.50% |
| Classification | Medium-carbon steel | Medium-carbon steel |
| Relationship | Closely related standard grades, not perfectly identical designations | |
| Corrosion resistance | Low – both steels require regular protection from moisture | |
Properties of S45C / AISI 1045 steel
The steel designation alone does not determine the final properties of the tool. Heat treatment, resulting hardness, edge geometry, forging method and the construction of the entire product are also decisive.
| Property | Practical significance |
|---|---|
| Hardenability | The steel can be heat-treated so that the working surface or edge achieves greater hardness. |
| Toughness | With suitable heat treatment, the material can withstand impacts better than very hard and brittle knife steels. |
| Edge retention | For working axes and tools, it offers practical durability, but it cannot be compared with premium highly alloyed knife steels. |
| Sharpening | The edge can usually be restored more easily than with highly alloyed or powder steels. |
| Corrosion resistance | The steel does not contain enough chromium for stainless properties and must be protected from moisture. |
S45C / AISI 1045 in axes and working tools
With an axe, the goal is not simply maximum hardness. An excessively hard edge could be more prone to chipping on impact, while an edge that is too soft would deform and become dull quickly. The manufacturer therefore selects the heat treatment as a compromise between working-edge hardness and the toughness of the tool.
In a traditional Warikomi construction, the cutting section made from S45C steel may be forge-welded into considerably softer steel. Such a solution combines a durable working edge with a body that helps absorb part of the impact energy.
Hardness depends on the manufacturer
The designation S45C or AISI 1045 alone cannot determine the exact hardness of a specific axe. The result depends on hardening, tempering, product dimensions and the intended method of use. The decisive information is always the specification provided by the manufacturer of the specific tool.
Care of carbon steel
Neither S45C nor AISI 1045 is stainless steel. They can corrode during prolonged contact with water, moisture, acids or salts. Regular care is therefore an important part of using the tool.
- After use, remove dirt, sap and wood residues from the surface.
- Dry the metal parts thoroughly.
- Apply a very thin layer of protective oil to the dry surface.
- Do not store the tool in a damp leather sheath.
- After working in the rain, allow the tool and sheath to dry separately.
- Remove developing rust before it penetrates deeper into the surface.
Patina is natural
Grey, blue or darker colouring of carbon steel is a normal patina. An orange to reddish-brown layer, on the other hand, is active rust and should be removed before protecting the surface with oil again.
Sharpening and restoring the edge
An S45C / AISI 1045 edge can be restored using suitable sharpening stones or diamond abrasives. When sharpening, it is important to preserve the original geometry of the tool. An edge that is too thin may be more prone to damage, while an excessively obtuse angle will reduce cutting performance.
For significant chipping, deformation or damage to the entire working edge, we recommend consulting an experienced sharpener. The equipment needed for regular maintenance can be found in the sharpening stones category.
Marek’s tip
With an axe, I would not choose based only on the highest hardness. For a working tool, toughness, edge geometry and the ability to make easy repairs in the field are also important. S45C is interesting precisely because it balances these properties – but it requires regular drying and protection with oil.
Working steel focused on strength and toughness
S45C / AISI 1045 is suitable for axes and tools where durability in use, heat-treatability and easy edge restoration are important.
Need advice?
Contact us by phone at +420 702 049 048, Monday to Friday between 7:30 and 16:00, or by email at info@dellinger.cz.
Frequently asked questions about S45C / AISI 1045 steel
Is S45C the same steel as AISI 1045?
Not completely. They are very closely related grades under different standards. Their chemical compositions overlap, but the permitted ranges of some elements are not perfectly identical.
How much carbon do these steels contain?
S45C typically contains approximately 0.42–0.48% carbon, while AISI 1045 contains approximately 0.43–0.50%.
Is it high-carbon steel?
No. S45C and AISI 1045 are technically classified as medium-carbon steels. In product texts they are sometimes referred to more generally as carbon steels.
Is S45C suitable for making axes?
Yes. With proper heat treatment, it offers a practical combination of strength, toughness, working-edge hardness and ease of sharpening.
What hardness does S45C have?
The exact hardness cannot be determined from the steel designation alone. It depends on hardening, tempering, product dimensions and the heat treatment used by the specific manufacturer.
Is S45C / AISI 1045 stainless?
No. The steel can corrode when exposed to moisture, so clean it, dry it and treat it with a thin layer of oil after use.
What does Warikomi mean?
Warikomi is a forged construction in which the harder material of the cutting section is inserted into softer steel and forge-welded into a single tool.
How is an AISI 1045 edge sharpened?
Suitable sharpening stones or diamond abrasives can be used. When sharpening, the original geometry of the working edge must be preserved.
Is patina on carbon steel a defect?
No. Grey or darker colouring is a natural patina. Orange to reddish-brown active rust should, however, be removed.
