Decoding Chinese Carbon Steel Names: Three Main Naming Patterns

If you’re sourcing carbon steel fasteners from China, you’ve seen them on most quotes and certificates: Q235, 45#, ML08Al etc. These codes are the industry standard, but here’s the problem: unless you know how to read them, they’re just random letters and numbers.

Unlike ASTM standards where you get names like “1018” or “1045,” Chinese carbon steel grades follow a different logic. Once you understand that logic, you’ll never look at a Chinese certificate with confusion again.

The Q Series – Named by Yield Strength

What you see: Q195, Q215, Q235, Q275 etc

What it means:

• Q = “Qu” (屈服) — Chinese for yield point

• Number = Minimum yield strength in MPa

• Example: Q235 means minimum yield strength of 235 MPa.

Where you’ll see it:

• Low-strength fasteners (Class 4.6 and 4.8)

• Washers, nuts for general construction

• Non-critical applications such as temporary structures or light fixtures

The Number Series – Named by Carbon Content

What you see: 10#, 15#, 35#, 45#, 55#, 65#

What it means: The two digits represent the average carbon content in hundredths of a percent (0.01%).

Examples:

• 10# = 0.10% carbon

• 45# = 0.45% carbon

• 65# = 0.65% carbon

The “#” symbol: The hash symbol is Chinese shorthand for “grade.” It is often omitted in technical documents, so “45” means the same as “45#.”

Where you’ll see it:

• 10# : Low-carbon steel for mild stampings, rivets

• 35# : Medium-carbon for Class 8.8 bolts, shafts

• 45# : The workhorse for 8.8-grade fasteners — equivalent to SAE 1045

• 65# : High-carbon for spring washers, snap rings, clips