SPCC-SD and SPCC-1B are two sub-grades of JIS G3141 SPCC cold-rolled steel coils, sharing the same core material properties but differing significantly in temper grade (hardness), surface finish, and application scenarios. SPCC-SD is a standard-temper, dull-matte finish cold-rolled steel coil ideal for painting, coating, and general forming; SPCC-1B is a full-hard, bright finish cold-rolled steel coil designed for high-strength, low-ductility applications.
As a professional supplier of JIS G3141 SPCC cold-rolled steel coils, GNEE STEEL provides both grades with strict standard compliance, precise specifications, and customized solutions to meet diverse industrial needs. Understanding their key differences ensures you select the optimal SPCC cold-rolled steel coil for your production, maximizing efficiency and product quality.
What Are JIS G3141 SPCC Cold-Rolled Steel Coils
JIS G3141 SPCC cold-rolled steel coils are commercial-grade low-carbon steel products defined by the Japanese Industrial Standard (JIS G3141), widely used in global manufacturing for their cost-effectiveness, reliable performance, and versatile processability. GNEE STEEL's SPCC cold-rolled steel coils strictly adhere to JIS G3141 standards, with consistent chemical composition, mechanical properties, and dimensional accuracy, making them the preferred choice for home appliances, automotive parts, metal furniture, and general fabrication.
JIS G3141 SPCC Material Properties (Core Specifications)
Both SPCC-SD and SPCC-1B belong to the SPCC grade, so they share the same fundamental material properties as specified in JIS G3141. Below are the detailed chemical and mechanical properties, verified by GNEE STEEL's quality control team to ensure data accuracy and batch consistency.
1. Chemical Composition (JIS G3141 Standard, Max %)
|
Element |
Content Range (Max %) |
Core Function |
|---|---|---|
|
Carbon (C) |
0.15 |
Provides basic strength; low content ensures good ductility and processability for forming operations |
|
Manganese (Mn) |
0.60 |
Enhances hardenability and toughness, reducing brittleness during cold rolling |
|
Phosphorus (P) |
0.050 |
Controlled impurity to avoid brittleness and ensure weldability |
|
Sulfur (S) |
0.050 |
Restricted to prevent hot shortness and improve machinability |
|
Silicon (Si) |
0.05 |
Trace element maintaining steel purity and consistent mechanical performance |
|
Iron (Fe) |
Balance |
Base element determining the core structure and overall performance of the steel |
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2. Fundamental Mechanical Properties (JIS G3141 Standard, Base for Both Grades)
The core mechanical properties of SPCC grade provide a foundation for both SPCC-SD and SPCC-1B, with key differences emerging from their tempering processes (standard vs full-hard). The base properties below apply to the SPCC grade as defined in JIS G3141:
Tensile Strength (Rm): ≥ 270 MPa (base value, varies by temper grade)
Yield Strength (Rp0.2): 140 - 280 MPa (base range for standard temper)
Elongation (A50): ≥ 34% (base value for standard temper)
Hardness (HRB): 50 - 85 (base range for standard temper)
Processability: Excellent weldability, stamping, and bending performance for general fabrication
SPCC-SD Surface Roughness Specification
SPCC-SD is a sub-grade of SPCC with a standard temper (S) and dull finish (D), optimized for excellent adhesion of paint, powder coating, and plating. Its surface roughness is strictly controlled in accordance with JIS G3141 standards, ensuring uniform texture and consistent performance across all batches of GNEE STEEL's SPCC-SD cold-rolled steel coils.
Below are the detailed SPCC-SD surface roughness specifications, verified by our quality control team to meet industrial application requirements:
|
Steel Grade |
Surface Finish |
Roughness (Ra) |
Roughness (Rz) |
Surface Characteristics |
Coating Adhesion |
|---|---|---|---|---|---|
|
SPCC-SD |
Dull (Matte), Non-Reflective |
0.8 - 1.6 μm |
6.3 - 12.5 μm |
Uniform matte texture, free from scratches, oxide scales, or bright spots; produced with mechanically or chemically roughened rolls |
Excellent for painting, powder coating, and plating; prevents paint peeling and ensures long-term adhesion |
Key Differences Between SPCC-SD and SPCC-1B Cold-Rolled Steel Coils
While SPCC-SD and SPCC-1B share the same SPCC base properties, their temper grade, surface finish, mechanical performance, and applications differ significantly. The following table and detailed explanations clarify their core distinctions to help you make the right selection.
Comprehensive Comparison Table (JIS G3141 Standard)
|
Comparison Item |
SPCC-SD Cold-Rolled Steel Coils |
SPCC-1B Cold-Rolled Steel Coils |
|---|---|---|
|
Temper Grade (JIS G3141) |
Standard Temper (S) – Annealed and skin-rolled; soft temper |
Full Hard (1) – No annealing after cold rolling; full-hard temper |
|
Surface Finish |
Dull (Matte) Finish (D) – Non-reflective, textured surface |
Bright Finish (B) – Smooth, reflective surface; produced with polished rolls |
|
Surface Roughness (Ra) |
0.8 - 1.6 μm |
0.4 - 0.8 μm |
|
Tensile Strength (Rm) |
≥ 270 MPa |
≥ 550 MPa (significantly higher) |
|
Yield Strength (Rp0.2) |
140 - 280 MPa |
≥ 450 MPa (significantly higher) |
|
Elongation (A50) |
≥ 34% (high ductility) |
≤ 8% (low ductility) |
|
Hardness (HRB) |
50 - 85 (soft, easy to process) |
≥ 85 (hard, wear-resistant) |
|
Formability |
Excellent – Suitable for stamping, bending, shallow drawing, and complex forming |
Poor – Not suitable for forming; ideal for flat parts or simple bending only |
|
Coating Adhesion |
Excellent – Matte surface enhances paint/plating adhesion |
Good – Smooth surface requires proper pre-treatment for optimal adhesion |
|
Thickness Range |
0.3 - 3.5 mm (flexible, wide range) |
0.15 - 1.8 mm (thinner range, typical for full-hard grade) |
|
Core Advantages |
Cost-effective, easy to process, excellent coating adhesion, versatile |
High strength, wear-resistant, smooth bright surface, dimensional stability |
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Applications of SPCC-SD and SPCC-1B Cold-Rolled Steel Coils
Understanding the key differences between SPCC-SD and SPCC-1B helps you select the right grade for your specific application. Both grades are widely used in various industries, but their unique properties make them suitable for distinct scenarios.
SPCC-SD Cold-Rolled Steel Coils: Ideal Applications
SPCC-SD is the most versatile sub-grade of SPCC, suitable for applications requiring formability and coating adhesion. Common uses include:
Home Appliances: Cabinets, panels, brackets, and inner components of washing machines, refrigerators, air conditioners, and microwave ovens
Automotive Industry: Interior trim parts, door panels, and non-structural components that require stamping and painting
Metal Furniture: Frames, panels, and accessories for office furniture, household furniture, and storage equipment
Electrical Enclosures: Casings for electrical equipment, control cabinets, and junction boxes (prior to coating)
General Fabrication: Stamped parts, shallow-drawn components, hardware, and decorative parts that require painting or plating
Substrate for Coating/Plating: Ideal base material for galvanized (GI/EG) and color-coated (PPGI) steel sheets
SPCC-1B Cold-Rolled Steel Coils: Ideal Applications
SPCC-1B is designed for high-strength, low-formability applications, leveraging its hardness and wear resistance. Common uses include:
Metal Strips: Fasteners, clips, springs, and brackets that require high strength and dimensional stability
Automotive Parts: Small structural components, door hinges, and reinforcement parts that do not require forming
Hardware: Nails, screws, washers, and other fasteners that need wear resistance and load-bearing capacity
Decorative Components: Bright surface parts that do not require coating, such as decorative trim and nameplates
Industrial Equipment: Flat components, guides, and wear plates that require high hardness
Frequently Asked Questions (FAQ)
Are SPCC-SD and SPCC-1B both compliant with JIS G3141 standards?
Yes. Both SPCC-SD and SPCC-1B are sub-grades of JIS G3141 SPCC cold-rolled steel coils, strictly complying with the chemical composition, dimensional accuracy, and surface quality requirements specified in the JIS G3141 standard. GNEE STEEL provides mill test reports (MTC) for every batch to confirm compliance.
Can SPCC-SD and SPCC-1B be interchangeable?
No. Due to their significant differences in hardness, ductility, and surface finish, they are not interchangeable. SPCC-SD is for forming and coating applications, while SPCC-1B is for high-strength, low-formability applications. Substitution will lead to production defects or product failure.
What is the surface roughness of SPCC-1B?
SPCC-1B has a bright, smooth surface with a roughness (Ra) of 0.4 - 0.8 μm, which is smoother than SPCC-SD (0.8 - 1.6 μm). Its smooth surface is ideal for applications where appearance is important or minimal surface friction is required.
Which grade is more cost-effective: SPCC-SD or SPCC-1B?
SPCC-SD is generally more cost-effective for most general fabrication applications, as its standard temper and wider thickness range reduce production costs. SPCC-1B has a slight cost premium due to its full-hard temper and precise bright surface finish.
Can SPCC-1B be bent or stamped?
No. SPCC-1B is a full-hard grade with low ductility (elongation ≤ 8%), making it unsuitable for bending, stamping, or deep drawing. It will crack or break under forming pressure. For forming applications, choose SPCC-SD.
What thickness ranges are available for SPCC-SD and SPCC-1B?
SPCC-SD: 0.3 - 3.5 mm (width 600 - 1500 mm); SPCC-1B: 0.15 - 1.8 mm (width 650 - 1300 mm). GNEE STEEL offers custom thickness and width according to your specific requirements.
Which grade is better for painting or plating?
SPCC-SD is better for painting or plating. Its dull (matte) surface (Ra 0.8 - 1.6 μm) provides excellent adhesion for paint, powder coating, and plating, reducing rework and ensuring long-term durability. SPCC-1B's smooth surface requires pre-treatment (e.g., sandblasting) to improve coating adhesion.
Does GNEE STEEL provide samples of SPCC-SD and SPCC-1B?
Yes. We provide free samples (up to 2 pieces per grade) for your testing and verification, including chemical composition, mechanical properties, and surface finish. Contact our sales team to request samples, and we will deliver them to you as soon as possible.