1. Tin & Terne Coated Steel

2. Resistance Welding Lesson Objectives When you finish this lesson you will understand: Learning Activities 1.View Slides; 2.Read Notes, 3.Listen to lecture 4.Do on-line workbook Keywords

3. Tin Plating Hot Dipped Electro-tin Plating Chromate Painted Post Plating Treatment

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

7. Making & Shaping of Steel, USS, 1964 FeSn 2 Eta FeSn zeta

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

9. Tin Coated Making & Shaping of Steel, USS, 1964 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

10. Typical Applications of Tin Coated Steels 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 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

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

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

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

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

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

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

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

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

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

31. Region of Optimum Weld (And Defects) Greer H, Begeman M, “Resistance Seam Welding of Terne Plate” Welding Journal, June 1960 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 High Current, High Force, Expulsion Pores Inconsistent, Insufficient Penetration Low Current, Low Force, Small nugget Porosity Low Force, Low Current Shrinkage Pores

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

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) Thick Sn = High R Low I Paint = High R Low I Increased Coating Thickness or Paint 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 Painted Tin Un-Painted Tin Painting Kimchi, M, et al, “Weldability of Hot-Dipped Tin-Coated Steel Sheet”, Welding Journal, June 1995

41. Un-Painted Tin AC Seam Weld Un-Painted Tin DC Seam Weld Painted Galvanneal Painted ZnNi Effect of DC Seam Welding on Tin Coated Steel 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) Soudronic @ 320 ipm Soudronic @ 400 ipm Results of Soudronic Welding on Unpainted Hot Dipped Tin Coated Steel