ST12 Steel
ST12 is a widely used cold-rolled low-carbon steel known for its excellent formability, weldability, and affordability. It is primarily utilized in general-purpose manufacturing where easy shaping and cost-effectiveness are prioritized, such as in automotive components, home appliances, and metal fabrication.
Basic Information
Definition: ST12 is a non-alloy cold-rolled steel with very low carbon content, characterized by high ductility and low strength. It is part of the German DIN standard series (DIN 1623) for cold-rolled strip steels, designed for simple forming processes like bending, stamping, and shallow drawing.
Corresponding Standards: Conforms to DIN 1623-1 (Cold rolled steel strip for cold forming). It is equivalent to:
European standard: DC01 (EN 10130)
Chinese standard: Q195 (cold-rolled)
American standard: ASTM A1008 CS Type B
Japanese standard: JIS SPCC
Key Characteristics: High formability, smooth surface finish, good weldability, and low cost, making it suitable for non-structural parts with minimal stress requirements.
Chemical Composition
ST12’s composition is optimized for formability, with strict control over carbon and impurity levels:
Element Content Range Role in the Steel
Carbon (C) ≤0.10% Kept low to ensure high ductility and minimize work hardening during forming.
Manganese (Mn) ≤0.50% Enhances strength slightly without reducing formability; aids in deoxidation.
Silicon (Si) ≤0.05% Controlled to avoid surface defects and ensure a clean, smooth finish.
Phosphorus (P) ≤0.035% Limited to prevent brittleness, especially in welded joints.
Sulfur (S) ≤0.035% Minimized to avoid hot shortness and improve surface quality.
Physical Properties
Density: ~7.85 g/cm³ (standard for carbon steels).
Melting Point: ~1430–1450°C.
Thermal Conductivity: ~50 W/(m·K) at room temperature (good heat transfer performance).
Coefficient of Thermal Expansion: ~12×10⁻⁶/°C (20–100°C), typical for low-carbon steels.
Electrical Resistivity: ~0.16 μΩ·m (moderate electrical conductivity).
Mechanical Properties
ST12’s mechanical properties prioritize formability over high strength:
Property Value Range (Cold-Rolled State)
Tensile Strength (Rm) 270–370 MPa
Yield Strength (Rp0.2) 130–220 MPa
Elongation (A80mm) ≥28%
Hardness ≤130 HV (Vickers hardness)
Formability: Excellent for simple to moderate forming operations, including bending (with small radii), stamping, and shallow drawing. It is classified as a “dead soft” steel, meaning it deforms easily under pressure.
Weldability: Outstanding—easily welded using common methods (arc welding, spot welding, gas welding) without preheating or post-weld treatment, due to its low carbon content.
Machinability: Good for basic cutting, drilling, and shearing, though its softness may cause tool buildup in high-speed machining.
Processing Performance
Cold Forming: ST12 is well-suited for:
Stamping: Producing flat or shallow-drawn parts like panels, brackets, and covers.
Bending: Can be bent to tight radii (e.g., 1× thickness) without cracking, suitable for hinges or folded components.
Roll forming: Shaping into profiles for construction or furniture.
Surface Treatment: Accepts painting, galvanizing, powder coating, and plating effectively, thanks to its smooth cold-rolled surface.
Joining: Welds and bonds well with adhesives, simplifying assembly in manufacturing.
Application Fields
ST12’s versatility and cost-effectiveness make it suitable for a wide range of applications:
Automotive Industry:
Interior trim parts (e.g., door panels, dashboard components).
Non-structural brackets, clips, and fasteners.
Home Appliances:
Casings for refrigerators, washing machines, and microwaves.
Internal parts like trays, supports, and panels.
Construction and Furniture:
Metal furniture frames, brackets, and decorative elements.
Ventilation ducts, gutters, and light steel components.
General Fabrication:
Signage, nameplates, and simple metal enclosures.
Packaging materials and metal containers.
Advantages and Limitations
Advantages
High Formability: Easily shaped into various geometries without failure.
Cost-Effective: One of the most economical cold-rolled steels, ideal for mass production.
Good Surface Quality: Smooth finish reduces the need for post-processing.
Excellent Weldability: Simplifies assembly in manufacturing processes.
Limitations
Low Strength: Not suitable for structural or load-bearing applications (use high-strength steels like HSLA or DP grades instead).
Poor Corrosion Resistance: Uncoated ST12 rusts easily in humid environments, requiring protective coatings for outdoor use.
Low Wear Resistance: Soft nature makes it prone to abrasion; not ideal for moving parts.
In summary, ST12 is a practical, low-cost cold-rolled steel ideal for general forming applications where formability and affordability are key. Its widespread use across industries highlights its reliability in everyday manufacturing.