A workshop owner ordered “EN8 round bar” for a batch of shafts. His drawing said C45. The bars looked the same, cut the same, and went through machining. After heat treatment, a few shafts did not reach the hardness the customer wanted. The steel was a close cousin, not the grade on the drawing, and the whole lot had to be checked again.
C45 is one of the most common steels in workshops, and one of the most commonly mixed up. This guide explains what it is and what to specify so the right bar, flat or plate arrives.
Quick answer: C45 is a medium carbon steel with about 0.45 percent carbon. It is stronger and harder than mild steel, machines well, and can be heat treated, which makes it a popular choice for shafts, axles, gears, pins, keys, bolts and machine parts. It is not meant for heavy welding. When you order, state the grade (C45), the form (round bar, flat or plate), the size, the delivery condition and whether you need a test certificate.
What Is C45 Steel?
C45 is a plain carbon steel, meaning it gets its strength mainly from carbon and not from alloy elements. Typical chemistry is:
- Carbon: about 0.42 to 0.50 percent
- Manganese: about 0.50 to 0.80 percent
- Silicon: up to about 0.40 percent
- Phosphorus and sulphur: kept low
Exact limits depend on the standard. The grade is commonly written as C45 (EN 10083). In Indian practice you will also see 45C8 under IS 1570. Always check the test certificate for the batch.
C45 vs Mild Steel
| Feature | Mild steel (IS 2062) | C45 medium carbon steel |
|---|---|---|
| Carbon content | Low (roughly 0.2 percent or less) | About 0.45 percent |
| Strength | Moderate | Higher |
| Heat treatment | Not usually hardened | Can be hardened and tempered |
| Welding | Easy | Difficult, needs preheating and care |
| Typical use | Structures, fabrication | Shafts, gears, pins, machine parts |
Common Uses of C45
- Shafts and axles
- Gears and sprockets
- Pins, keys, studs and bolts
- Spindles and machine components
- Hydraulic and pneumatic parts
- Tooling and fixtures
Delivery Conditions: Why It Matters
The same grade can behave differently depending on how it is supplied.
- Hot rolled (as rolled): the most common and lowest cost.
- Normalised: heat treated for a more uniform structure.
- Annealed: softer, easier to machine heavily.
- Quenched and tempered: higher strength, as per the required properties.
Mention the condition in your enquiry. If you plan to harden the part yourself, as-rolled or normalised is usually the right starting point.
What to Check Before You Order
- Grade written in full: “C45” or “45C8”, not just “carbon steel”.
- Form and size: round bar diameter, flat width and thickness, or plate thickness, width and length.
- Delivery condition: hot rolled, normalised or annealed.
- Test certificate: chemical analysis (carbon and manganese in particular) and mechanical properties.
- Straightness and surface: important for shafts that will be turned or ground.
- Quantity and delivery location.
Common Mistakes Buyers Make
- Using trade names loosely. Names like EN8 are often used for steels close to C45, but the chemistry is not identical. Write the grade on your drawing.
- Welding without preheating. Higher carbon makes C45 prone to cracking when welded cold.
- Ignoring the delivery condition. A bar that machines well in one condition may not in another.
- Skipping the test certificate. Without it, you cannot confirm the grade.
For other grade choices, see our guides on high tensile steel plates and boiler quality steel plates. To compare quotes, use our bulk steel quote checklist.
Frequently Asked Questions
What is C45 steel used for?
Shafts, axles, gears, pins, bolts, keys and general machine parts that need more strength than mild steel.
Is C45 the same as EN8?
They are close but not identical. Many workshops use the names loosely. If your drawing says C45, order C45 and ask for the test certificate.
Can C45 be welded?
It can be welded, but it needs preheating and careful procedure because of its carbon content. For heavy welded structures, mild steel is easier.
Can C45 be hardened?
Yes. It responds to hardening and tempering, and to surface hardening methods such as induction hardening.
Do you supply C45?
Medium carbon steel (C45) is part of our range. Tell us the form and size you need and we will confirm availability.
Do you supply from Bhavnagar and Surat?
Yes. See our Bhavnagar and Surat pages.
Need C45 Steel? Get a Clear Quote
Send us the grade, form, size, delivery condition, quantity and delivery location. We will confirm availability and come back with a clear quote.
Call 7226060911 or send your requirement below.
