What type of steel is used for cans?

What Type of Steel Is Used for Cans? The Direct Answer

The steel used for cans is low-carbon steel — specifically cold-rolled, continuously cast, aluminum-killed steel — surface-treated to resist corrosion and interaction with contents. In practice, this takes two primary commercial forms: Electrolytic Tinplate (ETP), where a thin tin coating is electroplated onto the steel base, and Tin Free Steel (TFS), also known as Electrolytic Chromium Coated Steel (ECCS), where a chromium and chromium oxide layer is applied instead of tin.

These two varieties of Can Body Steel account for the vast majority of metal food cans, aerosol cans, paint cans, and general-line packaging containers produced globally. The choice between them depends on the manufacturing process (welding vs. drawing), the product being packaged, required corrosion protection, and cost considerations. Beverage cans, by contrast, are almost universally made from aluminum alloy — a different material category discussed further below.

Electrolytic Tinplate (ETP): The Classic Can Body Steel

Electrolytic Tinplate is the most widely used Can Body Steel for food cans and three-piece containers. It consists of a cold-rolled low-carbon steel base sheet electroplated with a layer of commercially pure tin on both sides. The resulting structure — steel substrate, iron-tin alloy interface layer, and tin surface layer — delivers a combination of properties no single material could match alone.

Key Properties of ETP

• Corrosion resistance — The tin coating creates a physical and electrochemical barrier that prevents rust and slows chemical reaction between the steel and the packaged product.
• Weldability — Tin's electrical conductivity makes ETP well-suited to resistance welding — the dominant method for creating the side seam of three-piece can bodies, capable of producing up to 1,000 cans per minute on modern lines.
• Solderability — Tin bonds readily with solder, a historically important property for can seaming (though solder is no longer used for food cans in most markets).
• Formability — The soft, ductile tin layer lubricates the surface during forming operations, reducing tooling wear and enabling the drawing and ironing processes used for two-piece DI (Draw and Iron) cans.
• Metallic luster and print compatibility — ETP's bright, attractive surface is ideal for high-quality printing and lacquer application, making it the preferred material for decorative tins, artistic canisters, and premium food packaging.

Tin Coating Weight: Differential Tinplating

The tin layer in ETP is extraordinarily thin — approximately 0.38 micrometers on the thinnest commercial grades. Tin coating weights are specified in grams per square meter (g/m²) and range from 1.1/1.1 to 11.2/11.2 (inside/outside). Modern production uses differential tinplating — applying a heavier tin deposit to the inside surface (which contacts the product) and a lighter coating to the outside (where appearance and printability are the primary requirements).

Tin Free Steel (TFS / ECCS): The Cost-Efficient Alternative

Tin Free Steel (TFS), now more formally designated as Electrolytic Chromium Coated Steel (ECCS), was developed as an economical alternative to tinplate. Instead of tin, the low-carbon steel base is coated with a dual layer of metallic chromium and chromium oxide through an electrolytic chromic acid treatment process.

TFS offers several performance advantages over ETP in specific applications:

• Superior paintability and lacquer adhesion — Chromium oxide bonds exceptionally well with organic coatings (lacquers and polymers), making TFS the preferred substrate wherever a high-quality painted or lacquered finish is required.
• Economy — Chromium is less expensive than tin, making TFS a lower-cost option for high-volume applications where weldability is not required.
• Environmental advantage — The chromium coating process produces less waste than traditional tin electroplating at equivalent coating weights.

However, TFS has one critical limitation: it cannot be welded or soldered without first grinding away the metallic coating layers. For this reason, TFS is predominantly used for can lids, easy-open ends, DRD (Draw-Redraw) two-piece cans, and crown caps — applications where drawing and lacquering are the primary operations rather than side-seam welding. TFS must always be used with an organic protective coating (lacquer or polymer film) when it is in contact with food products.

Temper Grades: How Steel Hardness Is Specified for Can Making

Both ETP and TFS are produced in a range of temper grades that determine the steel's hardness, stiffness, and formability. Selecting the correct temper is critical: too soft and the can body deforms under pressure; too hard and the steel cracks during drawing or flanging operations.

Temper grades are divided into two categories based on the rolling process:

Single Reduced (SR) Tempers — T1 to T5

Single reduced steel is cold rolled to finished gauge, then continuously annealed and coated. The seven SR temper grades progress from T1 (softest, highest ductility) to T5 (hardest). In practice:

• T1 (Rockwell 30T hardness: 49) — Extra-deep drawn cans requiring maximum ductility.
• T2 (Rockwell 30T hardness: 53) — Printed cans and average deep-drawn applications.
• T2.5 (Rockwell 30T hardness: 55) — Standard can bodies, caps, and general applications requiring balanced ductility and strength.
• T3–T5 — Progressively stiffer grades for can ends, aerosol domes, and applications where dimensional stability under pressure is the priority.

Double Reduced (DR) Tempers — DR7 to DR10

Double reduced steel undergoes a second cold rolling pass after annealing, producing steel that is significantly stiffer, harder, and stronger than single reduced material at the same thickness. This increased strength allows lighter gauge steel to be used while maintaining equivalent structural performance — a key driver of material cost reduction in high-volume can manufacturing. DR grades (DR7.5, DR8, DR8.5, DR9, DR9M, DR10) are used for can ends, easy-open lids, and body applications where maximum rigidity is required.

Can Body Steel Thickness: The Specification Range for Different Can Types

The thickness of Can Body Steel varies significantly depending on the can format, contents pressure, and manufacturing process. The table below summarizes typical thickness ranges for major can applications:

The side seam weld on a three-piece welded can body produces a joint approximately 1.3 to 1.5 times the thickness of the base body plate, with a lap overlap of around 0.25–0.8 mm. Flanging, necking, and double-seaming operations must all account for the base steel's temper grade and rolling direction to avoid flange cracking or seam failures.

Three-Piece vs. Two-Piece Cans: How the Can Format Determines the Steel Grade

The two dominant can manufacturing formats impose fundamentally different requirements on Can Body Steel, and understanding this distinction is essential for material selection:

Three-Piece Cans (Welded Body + Two Ends)

The traditional three-piece can consists of a cylindrical welded body, a seamed bottom end, and a seamed top lid. The body blank is cut from tinplate sheet, rolled into a cylinder, and resistance-welded along the side seam at speeds up to 1,000 cans per minute. The weld produces a lap joint; the two body blank edges overlap by approximately 0.5 mm. This format is dominant for food cans (tomato, vegetable, fish, meat), paint cans, aerosol cans, and general-line containers. ETP is the preferred Can Body Steel for welded bodies due to its superior weldability.

Two-Piece DI Cans (Draw and Iron)

Two-piece Draw and Iron (DI) cans are formed from a single disc of steel — drawn into a cup, then passed through a series of ironing dies that progressively reduce wall thickness while increasing body height. The base remains full thickness; the wall is thinned to as little as 0.13 mm in some configurations. DI cans eliminate the side seam entirely, creating a seamless, inherently stronger body. This process demands exceptionally clean, inclusion-free steel with tightly controlled temper and gauge tolerances. DI cans are used for food products (processed goods, condensed milk) and some aerosol applications.

DRD Cans (Draw-Redraw)

Draw-Redraw (DRD) cans are produced by sequentially drawing a flat disc into progressively smaller diameter cups without thinning the walls. DRD cans are thicker-walled than DI cans, which provides structural strength without body beading. They are the standard format for tuna, salmon, sardines, and shallow food cans where a wide opening is needed. Both ETP and TFS are used for DRD can bodies, with T1–T2.5 tempers preferred to maintain ductility through the multi-stage drawing process.

Why Beverage Cans Use Aluminum, Not Can Body Steel

It is important to clarify a common point of confusion: standard beverage cans (for sodas, beer, energy drinks) are made from aluminum alloy, not tinplate steel. Aluminum rose to dominance in beverage canning for several reasons:

• Lower density — Aluminum is significantly lighter than steel, reducing transportation costs and delivering a lighter package to consumers.
• Superior DI formability — Aluminum's ductility allows extreme wall thinning in the Draw and Iron process, producing very thin-walled, lightweight beverage cans at high production speeds.
• Natural corrosion resistance — Aluminum does not rust in the way steel does, simplifying coating requirements for carbonated beverages.

Steel (ETP and TFS) remains the material of choice for food cans, aerosol cans, paint containers, and other packaging formats where structural rigidity, pressure resistance, weldability, and corrosion protection are the dominant requirements — and where the weight advantage of aluminum is less critical.

Internal Lacquer Coatings: The Non-Metallic Layer Inside Every Can

Regardless of whether the Can Body Steel is ETP or TFS, virtually all food cans and beverage-adjacent steel cans use an internal organic coating — lacquer or polymer lining — applied to the interior surface of the body and ends before forming or after seaming. This coating serves as an inert barrier between the metal and the product, preventing:

• Metallic taste transfer to the packaged food or beverage
• Corrosion from acidic or saline food products (e.g., tomatoes, citrus, pickles) that could degrade even the tin or chromium protective layer over time
• Reaction between sulfur-containing foods (meat, fish) and the steel surface, which can cause discoloration or sulfide blackening

TFS (ECCS) must always be used with an organic coating when in contact with food — it is never used uncoated for food applications. ETP can technically function without internal lacquer in some applications (e.g., certain chemical containers), but food-grade use universally specifies an internal coating regardless of the base metal treatment.

Hangzhou Jinma Metal Packaging: Can Body Steel and Tinplate Supply

Hangzhou Jinma Metal Packaging Co., Ltd. (hz-jinma.com), founded in 1983 and reorganized in 2000, is a professional enterprise located in the Gongshu Technical and Industrial Function Park in Hangzhou, Zhejiang Province, China. With a facility covering 38,000 square meters and ISO 9001 certification in place since 1989, Jinma specializes in superior metal coating and printing services for the packaging industry, with tinplate and Can Body Steel as core product categories.

Jinma's Can Body Steel and related tinplate product offerings include:

• Electrolytic Tinplate (ETP) — Supplied as coils and sheets in a range of temper grades, tin coating weights, and thicknesses to suit three-piece welded can bodies, food can ends, aerosol containers, and decorative tin packaging.
• Tin Free Steel / ECCS — Available in single-reduced and double-reduced grades for DRD can bodies, easy-open ends (EOE), and crown caps.
• Galvanized steel (tab stock) — Supplied in different thicknesses, widths, and hardness levels for EOE (Easy Open End) tab applications.
• Lacquered and printed tinplate — Pre-coated and printed sheets and coils ready for direct use in can body and end production, with lacquer formulations compliant with FDA and relevant food safety standards.

Packaging options are fully customizable to customer requirements, including plastic wrap, brown paper, paper angle bead, hardboard, fibre board, and wooden pallet configurations for export shipment. Jinma maintains long-term business relationships with major domestic and international customers, backed by their ERP-integrated management system and a commitment to high-quality, efficient service delivery.

How to Specify Can Body Steel: Key Parameters for Procurement

When sourcing Can Body Steel for can manufacturing, the following specifications must be clearly defined to ensure the material performs correctly in your production process:

1. Steel type — ETP (Electrolytic Tinplate) or TFS/ECCS (Tin Free Steel), determined by whether the body seam requires welding and the internal coating strategy.
2. Base steel grade — MR (standard corrosion resistance), L (low residuals), or D (extra-deep drawing) depending on forming severity and product compatibility.
3. Temper grade — T1 through T5 (single reduced) or DR7.5 through DR10 (double reduced), matched to the drawing depth, flanging requirements, and end-use pressure rating of the finished can.
4. Thickness and tolerance — Specified in millimeters, typically ranging from 0.13 mm to 0.50 mm for standard can-making applications, with gauge tolerances tightly controlled to ensure consistent forming performance.
5. Tin coating weight (for ETP) — Specified as differential (e.g., 2.8/2.8 or 5.6/2.8 g/m²) with heavier inside coating for product contact surfaces and lighter outside coating for decorative/printing purposes.
6. Surface finish — Bright, stone, or silver finish, affecting print adhesion, appearance, and lacquer bonding performance.
7. Lacquer or printing requirements — Whether the material is required plain (uncoated), lacquered only, or lacquered and printed, and any applicable food safety standards (FDA compliance, EU food contact regulations).
8. Form — coil or sheet — Coil form is standard for high-speed continuous can production lines; sheet form is used for lower-volume or custom-format production where blanking flexibility is required.