Food & Beverage Tinplate Sales: T2 Ba Surface BPA-Free, Airtight Sheets for Canned Goods Packaging

Product Description

Product Description

Tinplate is a tin-coated steel sheet (or strip) with a dual-layer structure: a steel substrate (core material) and a tin coating (surface layer). Its chemical composition and mechanical properties are determined by both the substrate and the coating, and they directly dictate its performance in packaging, electronics, construction, and other industries. Below is a detailed breakdown:
1. Chemical Composition of Tinplate
Tinplate's composition is divided into two parts: the steel substrate (the main structural component) and the tin coating (the protective/functional layer). The substrate type varies by application (e.g., food packaging vs. industrial use), while the tin coating follows strict purity standards.
1.1 Chemical Composition of the Steel Substrate
The steel substrate is typically low-carbon steel (or ultra-low-carbon steel) to ensure good formability (e.g., for shaping into cans) and weldability. The most common substrate grades are MR (Mild Steel for Drawing), L (Low Carbon), and D (Drawing Quality), with compositions compliant with international standards (e.g., ASTM A623M, GB/T 2520).

Component (Element)	Content Range (Mass Fraction)	Role & Function
Carbon (C)	≤ 0.12% (MR grade: ~0.05-0.10%)	Improves strength; too high reduces formability. Low carbon ensures the substrate can be deep-drawn (e.g., for can bodies).
Manganese (Mn)	≤ 0.60%	Enhances hardenability and tensile strength without significantly harming formability.
Silicon (Si)	≤ 0.03%	Minimizes surface defects (e.g., oxide scale) and ensures good tin coating adhesion. High Si can cause coating peeling.
Phosphorus (P)	≤ 0.025%	Lowers ductility if excessive; controlled to balance strength and formability.
Sulfur (S)	≤ 0.025%	Reduces hot workability (causes "hot shortness") if too high; strict limits prevent cracking during processing.
Iron (Fe)	Balanced (≥ 99.2%)	The base element of the steel substrate, providing structural rigidity.
Trace Elements	(e.g., Al: ≤ 0.05%, N: ≤ 0.008%)	Aluminum stabilizes nitrogen (prevents "aging" of steel), maintaining consistent mechanical properties over time.

1.2 Chemical Composition of the Tin Coating
The tin coating must be high-purity to ensure corrosion resistance (critical for food/chemical packaging) and compatibility with coatings (e.g., lacquers). International standards (e.g., ISO 11950) mandate:
Tin (Sn) Purity: ≥ 99.85% (high-purity tin avoids impurities like lead, which are toxic for food contact).
Allowed Impurities:
Lead (Pb): ≤ 0.02% (strictly limited for food-grade tinplate to meet FDA/EFSA safety requirements).
Antimony (Sb): ≤ 0.10% (prevents brittleness in the coating).
Copper (Cu): ≤ 0.08% (avoids discoloration and coating defects).
Post-Coating Treatments (Optional):
Chromate Passivation: A thin chromium-rich layer (Cr content: ~2-10 mg/m²) is applied to enhance corrosion resistance and lacquer adhesion.
Oil Coating: A food-grade mineral oil (e.g., dioctyl sebacate) is sprayed on the surface to prevent scratches during processing.
2. Mechanical Properties of Tinplate
Mechanical properties determine tinplate's ability to withstand processing (e.g., bending, deep drawing, stamping) and end-use stress (e.g., pressure in cans, impact in transportation). They are mainly determined by the steel substrate, while the tin coating (thin, ~2-15 g/m² per side) has minimal impact on overall mechanical performance.
Key mechanical indicators and their typical ranges (compliant with ASTM A623M, GB/T 2520) are listed below, categorized by substrate grade (since grades are designed for different processing needs):

Mechanical Property	Testing Standard	MR Grade (General-Purpose)	L Grade (Low-Strength, High Ductility)	D Grade (Deep-Drawing Quality)	Core Function
Tensile Strength (σb)	GB/T 228.1	320-420 MPa	280-360 MPa	300-400 MPa	Resists breaking under tension (e.g., can sealing).
Yield Strength (σs)	GB/T 228.1	180-280 MPa	150-250 MPa	160-260 MPa	Prevents permanent deformation (e.g., during stacking of cans).
Elongation (A)	GB/T 228.1	≥ 28% (A80mm)	≥ 32% (A80mm)	≥ 30% (A80mm)	Measures ductility (critical for deep drawing into can bodies; higher = easier to shape).
Vickers Hardness (HV)	GB/T 4340.1	60-80 HV	50-70 HV	55-75 HV	Indicates surface hardness (affects scratch resistance and stamping precision).
Bending Property	GB/T 232	180° cold bending (d=0, no cracks)	180° cold bending (d=0, no cracks)	180° cold bending (d=0, no cracks)	Ensures no cracking during folding (e.g., can lids, decorative tin edges). d=0 means bending over the same thickness.
** Erichsen Index (IE)**	GB/T 4156	≥ 7.0 mm	≥ 8.0 mm	≥ 7.5 mm	Evaluates deep-drawing ability (higher = more suitable for complex shapes like seamless cans).

2.1 Key Notes on Mechanical Properties
Directionality: Tinplate is a rolled product, so mechanical properties (e.g., elongation) differ slightly between the rolling direction (RD) and transverse direction (TD). Standards typically specify values for the direction with lower performance (e.g., TD for elongation) to ensure consistency.
Temper Designation: Tinplate is often labeled by "temper" (hardness/ductility level), such as T1 (soft, high ductility) to T5 (hard, low ductility). For example:
T2 temper (MR grade): Used for can bodies (requires deep drawing).
T4 temper (L grade): Used for can lids (requires rigidity for sealing).
3. Industry-Specific Requirements
Mechanical and chemical properties are tailored to end-use scenarios:
Food Packaging: Low carbon (≤0.08%), lead-free tin coating (≤0.005%), high elongation (≥30%) for shaping, and chromate passivation for corrosion resistance.
Electronics (Shielding): Higher tensile strength (≥380 MPa) for structural stability, and thin tin coating (2-5 g/m²) for conductivity.
Construction (Roofing): Thick substrate (0.3-0.5mm), high hardness (HV ≥70) for impact resistance, and heavy tin coating (10-15 g/m²) for weather resistance.
By adhering to these composition and property standards, tinplate balances functionality, safety, and processability across diverse industries.

Mechanical Properties
Temper Grade	Hardness(HR30Tm)	Yield Strength(MPa)
T-1	49±3	330
T-2	53±3	350
T-3	57±3	370
T-4	61±3	415
T-5	65±3	450
T-6	70±3	530
DR-7M	71±5	520
DR-8	73±5	550
DR-8M	73±5	580
DR-9	76±5	620
DR-9M	77±5	660
DR-10	80±5	690

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FAQ

Q1:What product information do I need to provide?
A:You need to provide the grade, width, thickness and the number of tons you need to purchase.

Q2:What are the shipping ports?
A:You can choose other ports according to your needs.

Q3:About product prices?
A:Prices vary from period to period due to cyclical changes in the price of raw materials.

Q4:What are the certifications for your products?
A:We have ISO 9001, SGS, EWC and other certifications.

Q5:How long does your delivery time take?
A:In general, our delivery time is within 7 - 45 days, and may be delayed if the demand is extremely large or special circumstances occur.