C45 Structural Steel Pipe

C45 (also known as 45# steel, 1045, or S45C) is a medium-carbon structural steel widely used in machinery, automotive, and construction due to its balanced strength, machinability, and cost-effectiveness. Below are its key properties and applications in pipe form:

1. Chemical Composition

Element	Content (%)	Notes
C	0.42–0.50	High carbon for hardness and wear resistance.
Si	0.17–0.37	Improves strength and oxidation resistance.
Mn	0.50–0.80	Enhances hardenability and toughness.
P/S	≤0.035	Low impurities for better weldability.
Cr/Ni	≤0.25/0.30	Residual elements for corrosion resistance.

Standards:

China: GB/T 699-1999 (45#)

International: ASTM A106 (1045), DIN EN 10297-1 (C45E), JIS G4051 (S45C) .

2. Mechanical Properties

Property	Value	Remarks
Tensile Strength	600–800 MPa	Varies with heat treatment.
Yield Strength	≥355 MPa	Post-quenching/tempering.
Hardness (HBW)	170–229	≤197 HB after annealing.
Elongation	≥16%	Balances ductility and strength.
Impact Toughness	≥39 J (-20°C)	Suitable for cold environments.