Product application

Hot-rolled products have excellent properties such as high strength, good toughness, easy processing and forming, and good weldability, so they are widely used in manufacturing industries such as steel, construction, machinery, boilers, and pressure vessels.

Application range:

(1) Processing into ordinary cold rolling after annealing;

(2) The galvanizing unit with annealing pretreatment device processes galvanizing;

(3) Panels that basically do not need to be processed.

1. Chemical Composition (Mass Percentage)

The main components of carbon steel coils are iron (Fe) and carbon (C), with other element contents adjusted based on grade and application requirements. Typical chemical compositions are as follows:

Element Typical Range Remarks

Carbon (C) 0.06%~0.35% Low-carbon steel (e.g., SPHC, Q195): typically ≤0.15%; Medium-carbon steel (e.g., Q235): ≤0.22%; High-carbon steel (e.g., 65Mn): up to 0.60%~0.90%.

Manganese (Mn) 0.30%~1.50% Enhances strength and hardenability. For example, SPHC: Mn ≤0.50%; Q345B: Mn 1.00%~1.60%.

Silicon (Si) ≤0.35% Acts as a deoxidizer and improves strength. Some grades allow trace additions (e.g., SPHC: Si ≤0.10%).

Sulfur (S) ≤0.035%~0.050% Excessive sulfur causes hot brittleness and must be strictly controlled (e.g., API 5L PSL2 requires S ≤0.015%).

Phosphorus (P) ≤0.035%~0.050% Excessive phosphorus reduces toughness. High-demand applications (e.g., low-temperature steel) require P ≤0.025%.

Other Elements Trace (e.g., Cu ≤0.40%, Cr ≤0.30%) Residual elements typically total ≤0.70% (e.g., EN 10111 standard).

Example Grades:

SPHC (JIS Standard): C ≤0.15%, Mn ≤0.50%, S ≤0.035%, P ≤0.035% (cold-rolled low-carbon steel coil).

Q235B (GB/T 700): C ≤0.20%, Mn ≤1.40%, S ≤0.045%, P ≤0.045% (general structural steel coil).

ASTM A36: C ≤0.26%, Mn ≥0.80%, S ≤0.050%, P ≤0.040% (hot-rolled coil for construction).