DX55D+AS120 Hot Dip Galvanized Steel Coil in Automotive Exhaust System Applications

DX55D+AS120 is a high-performance hot dip aluminized-silicon steel coil, optimized for automotive exhaust system components. Compliant with DIN EN 10346 (material number 1.0962) and ASTM A653 standards, it features a 120g/m² aluminum-silicon (+AS) coating (90% aluminum, 10% silicon) that delivers exceptional high-temperature resistance (up to 800°C), superior corrosion protection, and excellent deep-drawing formability.

DX55D+AS120 is ideally suited for non-welded, complex-shaped exhaust components such as heat shields, exhaust pipe sleeves, and intermediate exhaust connectors. Its unique combination of formability, heat resistance, and cost-efficiency makes it the preferred material for mainstream automotive exhaust systems, balancing performance and manufacturing economy while meeting global automotive industry standards.

DX55D+AS120 is a special deep-drawing low-carbon steel coil with a hot-dipped aluminum-silicon (+AS) coating, where "AS120" denotes a coating weight of 120g/m² (double-sided), forming a dense alumina protective layer on the surface. This coating is specifically engineered to address the harsh operating environment of automotive exhaust systems-continuous exposure to high temperatures (200°C-700°C during normal operation, up to 800°C during short-term spikes), corrosive exhaust gases (CO, NOx, sulfur oxides), and external moisture, dust, and road salts.

Automotive exhaust systems demand materials that balance formability (for complex shaping), high-temperature stability (to avoid coating delamination or material deformation), corrosion resistance (to extend service life), and cost-effectiveness (for large-scale production). DX55D+AS120 perfectly meets these requirements, outperforming traditional galvanized steel in high-temperature scenarios and offering a more economical solution than stainless steel 409 for non-welded components. As a key material for automotive exhaust systems, it is widely adopted by global automakers for its consistent performance and compliance with IATF 16949 automotive quality standards.

The performance advantages of DX55D+AS120 are closely aligned with the operational demands of automotive exhaust systems, ensuring reliability, durability, and manufacturability:

1. Superior High-Temperature Resistance (Critical for Exhaust Environments)

The +AS120 coating of DX55D forms a stable ternary alloy layer (aluminum-iron-silicon) at the steel-coating interface, which can withstand short-term high temperatures up to 800°C and long-term continuous service at 650°C-700°C-exactly matching the temperature range of automotive exhaust systems (exhaust manifold outlets reach 600°C-750°C, intermediate pipes and heat shields operate at 200°C-600°C). Unlike traditional pure zinc (+Z) coatings that melt at 419°C, the aluminum-silicon coating of DX55D+AS120 does not delaminate or oxidize under high temperatures, maintaining structural integrity and protective performance. Additionally, the coating has excellent heat reflectivity (about 80% light reflectivity), which helps reduce heat transfer to the vehicle body, protecting nearby components (e.g., wires, plastic parts) from thermal damage-a key advantage for exhaust heat shields .

2. Excellent Corrosion Resistance (Extending Exhaust Component Service Life)

Automotive exhaust components face dual corrosion threats: internal corrosion from acidic exhaust gases (sulfur oxides react with moisture to form sulfuric acid) and external corrosion from road salts, rainwater, and dust. The +AS120 coating of DX55D forms a dense alumina (Al₂O₃) film on the surface, which is inert and impermeable to corrosive media, effectively isolating the base steel from harsh environments. This corrosion resistance is several times higher than that of traditional galvanized steel, and even comparable to low-chromium stainless steel (409) in dry, high-temperature environments. Tests show that DX55D+AS120 exhaust components have a service life of 5-8 years under normal vehicle operation, meeting the automotive industry's requirement for exhaust system durability (minimum 5 years). The 120g/m² coating weight ensures sufficient thickness to resist wear and corrosion during long-term use, while the aluminum-silicon composition prevents the "white rust" issue common in pure zinc coatings .

3. Exceptional Formability (Adapting to Complex Exhaust Component Shapes)

Automotive exhaust components such as heat shields, exhaust pipe sleeves, and intermediate connectors often have complex curved, deep-drawn shapes, requiring materials with excellent cold-forming performance. DX55D is a special deep-drawing grade with a yield strength of 140-240 MPa, tensile strength of 270-370 MPa, and elongation (A80) of ≥30%, ensuring low forming resistance and no cracking during complex stamping and bending processes. The +AS120 coating has good ductility, which synchronously deforms with the base steel during forming without peeling or cracking-overcoming the problem of coating brittleness in traditional high-temperature coatings. This formability allows manufacturers to produce complex-shaped exhaust components in one stamping process, reducing production steps and costs. Compared to stainless steel 409 (which has poor cold-forming performance and is prone to cracking), DX55D+AS120 is more suitable for mass production of complex exhaust parts .

4. Cost-Effectiveness (Balancing Performance and Manufacturing Economy)

As a low-carbon steel with a hot-dipped aluminum-silicon coating, DX55D+AS120 is 30%-50% cheaper than stainless steel 409, while meeting the performance requirements of most non-welded exhaust components. For mainstream passenger cars and commercial vehicles, where cost control is critical, DX55D+AS120 provides an ideal balance between performance and cost-eliminating the need for expensive stainless steel materials for non-critical exhaust components. Additionally, the simple production process of DX55D+AS120 (hot dip coating) ensures stable supply and short delivery cycles, adapting to the high-volume production needs of the automotive industry. Its compatibility with existing stamping and forming equipment also reduces manufacturers' investment in new production lines .

5. Compliance with Automotive Industry Standards

DX55D+AS120 complies with international standards such as DIN EN 10346, ASTM A653, and IATF 16949 (automotive quality management system), ensuring consistent quality and performance across batches. It also meets the environmental requirements of RoHS and REACH, making it suitable for global automotive markets. The material has passed strict automotive industry tests, including high-temperature cycling, corrosion resistance (salt spray test), and formability tests, confirming its reliability in exhaust system applications. Its equivalent grades (e.g., JIS G 3302 SGCH+AS, GB/T 2518 DC55D+AS120) ensure compatibility with regional automotive manufacturing standards .

Based on its performance characteristics, DX55D+AS120 is mainly used in non-welded, complex-shaped exhaust components that require high-temperature resistance, corrosion resistance, and formability. 

1. Exhaust Heat Shields (Engine & Exhaust Pipe)

2. Exhaust Pipe Sleeves & Intermediate Connectors

3. Exhaust Muffler Covers

4. Non-Welded Exhaust Bracket Components

To ensure optimal performance of DX55D+AS120 in automotive exhaust systems, strict adherence to technical specifications and processing requirements is essential:

• Key Technical Specifications (Automotive Exhaust Special Grade)

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1. What does "AS120" mean in DX55D+AS120?

"AS" refers to Aluminum-Silicon Alloy coating (90% aluminum, 10% silicon), and "120" denotes the coating weight of 120g/m² (double-sided). This coating weight ensures sufficient thickness for long-term corrosion resistance and high-temperature stability, making DX55D+AS120 suitable for automotive exhaust systems.

2. Can DX55D+AS120 be used for exhaust manifolds?

No. Exhaust manifolds operate at extremely high temperatures (750°C-900°C) and require welding, which is not suitable for DX55D+AS120 (welding damages the +AS coating). Exhaust manifolds are typically made of stainless steel 409 or high-temperature alloy steel. DX55D+AS120 is suitable for non-welded components like heat shields and intermediate connectors.

3. What is the service life of DX55D+AS120 exhaust components?

Under normal vehicle operation (100,000-150,000 km), DX55D+AS120 exhaust components have a service life of 5-8 years, meeting the automotive industry's minimum requirement of 5 years. This is attributed to the +AS120 coating's excellent corrosion and high-temperature resistance.

4. Is DX55D+AS120 compatible with automotive stamping equipment?

Yes. DX55D+AS120 has excellent formability (yield strength 140-240 MPa, elongation ≥30%) and is compatible with existing cold stamping and bending equipment for automotive components. No additional equipment modifications are required, reducing manufacturing costs.

5. How to avoid coating damage during processing of DX55D+AS120?

To avoid coating damage, use polished forming dies to reduce friction, control forming speed (10-20 strokes/min), and avoid sharp edges contacting the material. After forming, clean the surface with neutral cleaning agents (avoid acidic/alkaline agents) and apply high-temperature resistant paint to protect the coating.