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Tin & Terne Coated Steel

Tin & Terne 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. Tin Plating. Hot Dipped Electro-tin Plating. Post Plating Treatment.

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Tin & Terne Coated Steel

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  1. Tin & Terne 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. Tin Plating • Hot Dipped • Electro-tin Plating Post Plating Treatment • Chromate • Painted

  4. Tin Coated - 3% US Product is Hot Dipped Making & Shaping of Steel, USS, 1964

  5. Tin Coated - 3% US Product is Hot Dipped Making & Shaping of Steel, USS, 1964

  6. Eta Zeta Making & Shaping of Steel, USS, 1964

  7. FeSn2 Eta FeSn zeta Making & Shaping of Steel, USS, 1964

  8. Tin Coated - 97% is Electrolytic Acid Process: Alkaline Sodium-stannate Bath: Line speed = 2000 ft/min Coating Melted to give Bright Appearance Alloying? Making & Shaping of Steel, USS, 1964

  9. Tin Coated 14 Million Tons of Electrolytic Tinplate per Year • Typical • Light Gage Strip 0.006-0.012 inch • Thickness 6 to 30 Chromate Passivation Film Oil Application Making & Shaping of Steel, USS, 1964

  10. Black Plate (no Tin) Temper Roll Start Material Tin Coated Ornamental Uses Tin Coated & Chromate Oil filter Heater components Food Storage Containers Tin Coated & Painted Gas Tanks Typical Applications of Tin Coated Steels • Resistance Seam Welding Most Common Process • 60 Hz AC Seam Weld • 400 Hz AC Seam Weld • DC Seam Weld • Soudronic Weld

  11. Black Plate Hot Dipped Tin • BP higher Static R (cold worked) • HDT low R (annealed in HD), higher F causes reduction (break of oxide) • Dynamic BP reduced R (CW annealed), HDT increased R (Temp effect) Ichikawa, M, “The study of high-speed seam welding of material for cans” Trans ISIJ, 1983

  12. 400 Hz Seam Weld Electrolytic Tin-Chromate Coated Steel (Effect of Coating Thickness) Variations in Coating Thickness (listed on next slide) Yoshida, M, et al “Effect of Tin Pre-treatment on Seam-weldability of Chromium Plated Steel Sheets”, Trans. Iron & Steel Inst. Of Japan, 1987

  13. 400 Hz Seam Weld Tin Coated Steel • Available Current Range Extends as Tin Coating Weight Increases • Contact Resistance Decreases, Soft Sn allows Cr oxide to break • With only one side Sn the resistance is still too high Yoshida, M, et al “Effect of Tin Pre-treatment on Seam-weldability of Chromium Plated Steel Sheets”, Trans. Iron & Steel Inst. Of Japan, 1987

  14. One Side Sn Coating • Coating on only one side causes center of heat zone to depart from interface Yoshida, M, et al “Effect of Tin Pre-treatment on Seam-weldability of Chromium Plated Steel Sheets”, Trans. Iron & Steel Inst. Of Japan, 1987

  15. Hansen, Constitution of Binary Alloys, McGraw-Hill 1958

  16. Welding of Tinplate by Soudronic Welding of Cans A = Feeder B = Roll-Former C = Can Body Transfer D = Welding AWS Welding Handbook

  17. AWS Welding Handbook

  18. Welding Problems with Tin Plated Steels • To Assure Consistent Weldability of Tinplate, You Must Specify: • Base Metal Composition, thickness, temper, & surface finish • Coating Thickness & Reflow Process • Passivation Treatment • Oil Treatment

  19. A Level of 0.5% Tin in Weld Metal Can Cause Embrittlement

  20. Surface Cracking • Sn Liquid Metal Embrittlement • Originating at Knurl Marks • Prevalent in AC & DC Seam Welds • Not Common in Soudronic Welds Kimchi, M, et al, “Weldability of Hot-Dipped Tin-Coated Steel Sheet”, Welding Journal, June 1995

  21. Terne Coating Travel Speed Controls Thickness Clean Sheet Palm Oil Terne Metal 80%Pb - 20%Sn (3-20%) 620 - 680 F (Pb Insoluble in Fe, Sn helps wet)

  22. AWS Welding Handbook

  23. Typical Applications of Terne Coated Steels • Long Terne • Gas tanks • Fuel lines • Brake lines • Radiator parts • Heater parts • Air cleaners

  24. Seam Welding of Terne Coated Steel Resistance Seam Welding - Most Common 0.025-0.062 inch thick steel 0.16 to 0.42 oz/sq ft Steels thicker than 0.125 are difficult to weld Typical Electrode Face = 0.20 to 0.31 in. Welding Speeds = 60-100 ipm • Precautions often Taken • Removal of Dirt and Oil Films Recommended • Oxide Build-up on Wheels often Continuously Removed

  25. AWS Welding Handbook

  26. Electrode Wear Greer H, Begeman M, “Resistance Seam Welding of Terne Plate” Welding Journal, June 1960

  27. Electrode Deterioration Water Spray Less Cooling More Alloying In Center Initially Arcing occurs Electrode Sticking Shortly Alloy Layer Knurl Impressions Pb Sn Centerline Crack Pb Sn Zn Boiling Point C 1725 2270 906 (Zn Vaporizes Before Alloying) Only about ½ Electrode life compared to Galvanized Additional Cooling Water Improves Electrode Life Greer H, Begeman M, “Resistance Seam Welding of Terne Plate” Welding Journal, June 1960

  28. Electrode Force/Weld Current (Pulse 3 on - 2 off) Higher Electrode Force Required to get Coating Out Molten Terne Coating Flows Out Heat Flows out with coating Resulting in Higher Weld Current Needed Entrapped Coating Remains as Inclusion Defect (Pulse 3 on - 2 off) Greer H, Begeman M, “Resistance Seam Welding of Terne Plate” Welding Journal, June 1960

  29. Region of Optimum Weld (Current, Force, Travel Speed, Pulse 3-2) 100 ipm Travel Speed 60 ipm Greer H, Begeman M, “Resistance Seam Welding of Terne Plate” Welding Journal, June 1960

  30. Current Range as a Function of Gage Greer H, Begeman M, “Resistance Seam Welding of Terne Plate” Welding Journal, June 1960

  31. Region of Optimum Weld (And Defects) Flashing, Surface Scalding High Current, Low Force, Excessive Penetration, Surface Expulsion Transverse Cracks High Penetration, Hot Surface, Liquid Metal Embrittlement Severe Surface Indentation High Force, Very high Current, High Penetration, Hot Deformation Porosity Low Force, Low Current Shrinkage Pores Porosity High Current, High Force, Expulsion Pores Inconsistent, Insufficient Penetration Low Current, Low Force, Small nugget Greer H, Begeman M, “Resistance Seam Welding of Terne Plate” Welding Journal, June 1960

  32. Current Pulse Control • Variable Heat Time • Only slight effect on penetration • Increase heat time increased nugget length, improved overlap • Increased Cool Time • Sharply reduce the amount of current required to produce a given nugget penetration SEE NOTES Greer H, Begeman M, “Resistance Seam Welding of Terne Plate” Welding Journal, June 1960

  33. Welds made with 3 cycle cool time were about equal in quality to 2 cooling cycles except nugget overlap was lacking A cool time of 2 cycles normally produced good welds with less porosity and shrinkage defects. Reducing the cool to 1 cycle tended to overheat the weld area and cause porosity and shrinkage cracks in the nugget Greer H, Begeman M, “Resistance Seam Welding of Terne Plate” Welding Journal, June 1960

  34. Spot Welding of Terne Coated Steel Resistance Spot Welded - AWS Reports Good Results Obtained With Class II Electrodes Truncated Cone with 0.25 Face Diameter Current, Time, Force = 15-30% Greater Than Bare Steel

  35. AWS Welding Handbook

  36. Some Comparisons Between Tin and Terne Welding

  37. Comparison Study – Seam Welding of HD Tin and Terne (Painted and Unpainted) Kimchi, M, et al, “Weldability of Hot-Dipped Tin-Coated Steel Sheet”, Welding Journal, June 1995

  38. AC Seam Weld Lobe Curve Effect of Paint on Terne and Effect of Tin Coating Thickness (0.35 mils/side & 0.55 mills/side) Increased Coating Thickness or Paint • Thick Sn = High R Low I • Paint = High R Low I Kimchi, M, et al, “Weldability of Hot-Dipped Tin-Coated Steel Sheet”, Welding Journal, June 1995

  39. Effect of Substrate Thickness on AC Seam Welding of Tin Coated Substrate Thickness Kimchi, M, et al, “Weldability of Hot-Dipped Tin-Coated Steel Sheet”, Welding Journal, June 1995

  40. Effect of Painting on AC Seam Welding of Tin Coated Painted Terne Painting Painted Tin Un-Painted Tin Kimchi, M, et al, “Weldability of Hot-Dipped Tin-Coated Steel Sheet”, Welding Journal, June 1995

  41. Effect of DC Seam Welding on Tin Coated Steel Painted ZnNi Un-Painted Tin DC Seam Weld Un-Painted Tin AC Seam Weld Painted Galvanneal Kimchi, M, et al, “Weldability of Hot-Dipped Tin-Coated Steel Sheet”, Welding Journal, June 1995

  42. DC @ 110 ipm (Max Speed w/o Defects) Results of Soudronic Welding on Unpainted Hot Dipped Tin Coated Steel Soudronic @ 320 ipm Soudronic @ 400 ipm Kimchi, M, et al, “Weldability of Hot-Dipped Tin-Coated Steel Sheet”, Welding Journal, June 1995

  43. Questions?

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