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Aluminum Coated Steel

Aluminum Coated Steel. Resistance Welding. Learning Activities View Slides; Read Notes, Listen to lecture Do on-line workbook. Lesson Objectives When you finish this lesson you will understand:. Keywords. Aluminized Coated Steel. Hot Dipped (continuous or batch) Electroplated

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Aluminum Coated Steel

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  1. Aluminum Coated Steel

  2. Resistance Welding • Learning Activities • View Slides; • Read Notes, • Listen to lecture • Do on-line workbook • Lesson Objectives • When you finish this lesson you will understand: Keywords

  3. Aluminized Coated Steel • Hot Dipped (continuous or batch) • Electroplated • Thermal Spraying • Powder Coating with Fusion • Diffusion Coating We will consider these

  4. Hot Dipped Aluminum Coating Type 1: Al - 8% Si (Oxidation Resistance Up to 1200F - 649C)- Reduced Formability T1-40 = 0.40 oz/ sq ft (0.001 inch thick) T1-25 = 0.25 oz/ sq ft (0.0005 inch thick) Type 2: Commercially Pure Al (Atmospheric Resistance at RT) Lower Electrical Resistance 0.75 oz/ sq ft (0.002 inch thick)

  5. Hot Dipped Aluminum Coating Type 2 Al Iron-Aluminide Fe ASM Handbook , Vol 1, 1990

  6. Aluminum Coated Automotive exhaust systems Typical Applications of Coated Steels

  7. Diffusion Aluminizing Pure Aluminum Coating + Diffusion Heat Treatment (Applied by Any of the previous processes) (Furnace Heat Treatment)

  8. AWS Welding Handbook

  9. Welding Hot Dipped Aluminum Coated Steel

  10. Welding Aluminum Coated Steels Spot Welding • Welding Current 20-50% higher than uncoated steel • Electrode Force 20-50% higher than uncoated Steel • Weld Time 40-60% longer than uncoated steel • Electrode Dressing somewhat more frequent than Galvanized Steel • Class II Truncated Cone Electrodes have been successful • More electrode indentation with type 2 Aluminized Sheet because it has lower resistance than type 1 Aluminized & generally Thicker Coating

  11. AWS Welding Handbook

  12. Welding Aluminum Coated Steels Projection Welding Benefit of Projection Welding: Reduces need for frequent electrode dressing • Type 1 coating • Recommend slightly larger projects than for Uncoated steel • Normally flat class II Electrodes Recommended

  13. Welding Aluminum Coated Steels Seam Welding • AWS Recommendations: • 20 - 50% greater welding current than bare steel • 20 - 50% greater pressure than bare steel • Class II wheels wit Type 1 Material • Pick up of Aluminum on Wheel must be countered • Knurled Drive Wheel • Power Brushes • Large amount of flood water • Mash seam welding is sometimes hampered by the refractory Oxide present AWS Welding Handbook

  14. Welding Aluminum Coated Steels ERW & High-Frequency Seam Welding • Both 60 Hz and High Frequency Welds can be made • Edges must be square & free of Aluminum to prevent Aluminum Oxide, thus Centerline defects

  15. Welding Diffusion Aluminized Metals

  16. Welding Diffusion Aluminized Metals Close to the same as welding uncoated steel with one exception noted below Aluminum Above 1% in the Weld Can Significantly Reduce Ductility and Cause Embrittlement

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