SES N 3128 Electro-Galvanized Sheet Steel

Developed by Suzuki Motor Corporation as part of its standards for cast iron and iron-based materials, the “SES N 3128 Electro-galvanized steel sheet” standard is Suzuki's defined standard for electro-galvanized steel sheets for automotive applications. This standard covers sheet and strip materials where a zinc coating has been applied to the surface of the steel using an electrolytic method.

The use of electro-galvanized sheet steel in the automotive industry is based on its smooth surface, controlled coating, and good formability, particularly for parts where appearance and precision are more important than extreme corrosion resistance.

The most suitable applications for electro-galvanized steel are as follows:

• Interior and semi-exposed parts:
• Instrument panel enhancements
• Seat frames and seat rails
• Internal brackets and supports
• HVAC enclosures
• Fine, delicate parts:
• Electronic control unit (ECU) housings
• Sensor brackets
• Relay/fuse boxes
• Body (selective fields)
• Interior door panels
• Ceiling interior structures
• Support poles (areas not exposed)

The reasons for using electro-galvanized steel in these areas are as follows:

• Smooth finish: ideal for painting.
• Thin zinc layer: will not crack during shaping.

Production processes of electro-galvanized steel:

• Stamping/shaping: Electro-galvanized steel is typically cold-rolled + electro-coated. Therefore,
• It performs well in deep drawing.
• It has low surface friction.

Applications include bending, deep drawing, and drilling. It is advantageous because it exhibits minimal surface defects after forming.

• Welding (very important): Common methods include: resistive spot welding and projection welding. This electro-galvanized steel is preferred for the following reasons:
• Thin coating: less electrode wear.
• More stable weld quality compared to hot-dip galvanized steel.
• Painting and coating: This is one of the biggest advantages. The process includes:
• Cleaning / degreasing
• Phosphating
• Electroplating
• Top coat paint

A smooth surface provides the following:

• Excellent paint adhesion.
• High-quality visual surface
• Corrosion protection strategy: Since electro-galvanized steel has moderate corrosion resistance, it is often used in conjunction with:
• Paint systems (electrocoating + topcoat)
• Sealing materials for joints
• Adhesives for edge flanges
• It is generally not used alone in harsh outdoor environments.

Electro-galvanized steel is preferred in the following situations:

• When surface quality is critical
• When tight dimensional tolerances are required
• If the part is to be painted
• If complex shaping is required

It should be avoided in the following situations:

• If the part is exposed to: road salt and water splash areas
• If high corrosion resistance is required

In these situations, the following are used:

• Hot-dip galvanized steel
• Galvanized steel

The SES N 3128 standard generally defines the following parameters:

• Material properties:
• Base steel grades (e.g., drawing/deep drawing grades)
• Coating type and thickness (generally low to medium zinc content)
• Mechanical properties (yield strength, tensile strength, elongation)
• Surface quality (smooth / fingerprint-resistant / phosphated, etc.)
• Surface treatments:
• Oily
• Phosphate
• Chromate or non-chromate coating
• Fingerprint-resistant coating

The advantages of electro-galvanized steel material are as follows:

• High surface quality (very smooth and glossy)
• Good moldability
• Weldability (spot welding suitability)
• Excellent surface for painting and coating.
• Fine tolerance control

The disadvantages of electro-galvanized steel material are as follows:

• Lower corrosion resistance compared to hot-dip galvanizing.
• Limited use for outdoor environments.

Electro-galvanized steel sheets, within the scope of the SES N 3128 standard, are used particularly in the following areas:

• Interior and visible parts:
• Interior trim pieces
• Seat mechanism parts
• Instrument panel supports
• Thin sheet metal pieces:
• Door interior panels
• Electronic enclosure boxes
• Sensor and control module housings
• Precision-formed parts:
• Deep drawing parts
• Small brackets and fasteners

Electro-galvanized sheet metal has a high surface quality and is ideal for painting and coating. The thin coating provides an advantage during pressing and forming.

The main reasons why the SES N 3128 standard is critical in the automotive industry are as follows:

• Quality standardization
• Guaranteed corrosion resistance performance.
• Surface and coating compatibility (paint, welding)
• Consistency in pressing and production processes.
• Environmental requirements (such as chromium-free coatings)

Electro-galvanized steel differs from hot-dip galvanized steel in the following ways:

• Coating thickness: Electro-galvanized steel material is thin, while hot-dip galvanized material is thick.
• Surface quality: Electro-galvanized steel material is very smooth, while hot-dip galvanized material is rougher.
• Corrosion resistance: Electro-galvanized steel material has a medium level, while hot-dip galvanized material has a high level.
• Usage: Electro-galvanized steel is preferred for interior and visible parts, while hot-dip galvanizing is preferred for the exterior casing and chassis.

In short, the SES N 3128 standard is a critical material standard that guarantees the following properties for electro-galvanized steel sheets used in the automotive industry:

• High surface quality
• Controlled corrosion resistance
• Good moldability

The reasons why electro-galvanized steel is preferred by engineers are as follows:

• Excellent surface quality.
• Consistent shaping performance
• Better weldability compared to thick zinc coatings.
• Superior paint quality.
• Lower coating variability

The SES N 3128 standard is not the strongest corrosion protection solution, but when combined with coatings, it provides superior performance.

For many years, our organization, with its competent and experienced team, has been understanding the needs of its clients, providing the advanced testing services they require, and assisting them in the establishment, implementation, and improvement of management systems. Within this framework, we also provide testing services compliant with the SES N 3128 standard.