Nickel Base Alloys

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

Fe (9.7) AWS Welding Handbook

Nickel Base Alloys Can Be Divided into Categories Commercially Pure Nickel Solid-Solution Alloys Precipitation-Hardenable Alloys Dispersion-Strengthened Alloys (ThO 2 ) Ni-Ti Shape Memory Alloys

Decker, R., Strengthening Mechanisms in Nickel- Base Superalloys, International Nickel, 1970

AWS Welding Handbook

Note Variation Pure Fe = 9.7 pure SSppt disp

Pure Nickel - Alloy 200 Food processing equipment Caustic handling equipment Chemical Shipping drums Electrical & electronic parts Susceptible to graphitization at grain boundaries at elevated temperatures. Alloy 201 Used for service above 600F because: Has low carbon which promotes increased resistance to graphitization at elevated temps

Solid Solution Nickel - Copper (400, R-405) Resistance to Sea Water, chlorination Naval Application, Chlorination Plants, Water meter parts, pump shafts, feed water heaters Nickel-Chromium (600, 601, 690, 214, 230, G-30, RS-330) Corrosion Resistance at Elevated Temp Furnace muffles, heat treating equipment, nuclear steam tubing, heat exchangers, aircraft engine components Nickel-Iron-Chromium (800, 800HT, 825, 20Cb3, N-155, 556) High Temp Strength, Resistance to Oxidation Heat exchangers, carborizing fixtures, pickling tank heaters, spent nuclear fuel element recovery, hydrofluoric acid production

Solid Solution Cobalt-Chromium-Nickel-Tungsten (L-605, 188, S-816, 54Co-26Cr) Sensitive to Copper contamination Nickel-Chromium-Molybdenum (C-22, C-276, G, S, X, 622, 625, 686) Corrosion resistance at room temp Nickel-Molybdenum (B, B-2, N, W) Low temp corrosion resistance, some acids Cryogenic Service

Precipitation-Hardenable Alloys Gamma Prime Precipitate Nickel-Copper Alloys (K-500) Resistant to Sea Water, Chlorine Pump shafts, impellers, oil well drill collars, electronic components, springs Sensitive to strain age cracking Nickel-Chromium (713C, X-750, U-500, R-41, Waspalloy) Al-Ti-Nb strengthening Good high temp oxidation Gas turbine components Nickel-Iron-Chromium (901, X-750) Forging applications generally not welded

Relative Weldability of PPt Alloys AWS Welding Handbook

Thorium Dispersion Strengthened Nickel TD Nickel High Temperature Strength Thermal Shock Resistance – Used for Turbine components Can have considerable loss of strength in weld, due to agglomeration or growth of thoria dispersoid. TD NiCr High Temperature Strength Oxidation and Sulfidation Resistance Fansteel Metals Division Bulletin,

Ni-Ti Shape Memory Alloy 55Ni- Bal Ti Reversible Martensite Potluri, N. “Joining of Shape Memory Alloys” Welding Journal, March 1999

Spot Welding Electrical Resistance Range from 9.5 to over 130 micro-Ohm Cm (1-13 times that of Plain Carbon Steels) Welding Current similar to steel for low resistance Current lower for higher resistance alloys Short Weld Time Because of short time, generally no atmosphere required Strength Range from 0.8 to 3.8 times Plain Carbon Steel For Lower Strength Materials Same Force Levels For High Strength (at Elevated Temp) Higher Forces a. Expulsion = Force too low b. Electrode Mushroom = Force too high Because of wide variations in properties Exact welding conditions vary widely

Spot Welding Resistance Welding Manual, RWMA For thin material up to 0.06” If tip sticking go to 10 o For heavier material ” 5-8”

AWS Welding handbook

Spot Welding Thicker Gage 73Ni-16Cr-7Fe-3Ti Resistance Welder Manufacturers Association Bulletin # 26

Spot Welding Thicker Gage 73Ni-16Cr-7Fe-3Ti Resistance Welder Manufacturers Association Bulletin # 26 Thickness

Spot Welding Frequency Converter AWS Welding handbook

Spot Weld Defects Hot Cracking lower S&P forge force Coring higher R in GB Constitutional Liquation Reduce particles in HAZ Sulfur HAZ Surface Cracking Oil, Grease, Marking Pencil on Surface Resistance Welding Manual, RWMA

Projection Welding Seldom Projection Welded because Production Runs are usually small Higher Weld Forces and longer weld times required than for Plain Carbon Steel because of higher elevated Temperature Strength

Cross Wire Welding Resistance Welding Manual, RWMA

Seam Welding Upper Electrode Wheel Workpiece Lower Electrode Wheel Throat Knurl or Friction Drive Wheel Roll Spot Weld Overlapping Seam Weld Continuous Seam Weld [Reference: Welding Handbook, Volume 2, p.553, AWS] Intermittent Pulse, Intermittent Roll, Forge Force Possible No Intermittent Roll, No Forge Possible Class 1 or 2 Rolls Burnished to Prevent Sticking

Seam Welding

Flash Welding Higher upset force because of higher hot strength than plain carbon steel Higher Clamping Forces because higher upset forces Die burn = Insufficient Clamping Force Resistance Welding Manual, RWMA

High flashing speeds (parabolic vs. linear) and shorter flashing times used to minimize weld contamination. Flash Welding Jaw spacing less because higher resistance Upset distance sufficient to get all molten material out Higher resistance may cause some centerline melting Resistance Welding Manual, RWMA

Flash Welding Current Flow During Upset If flashing current is cut off before upset, oxide forms at centerline Resistance Welding Manual, RWMA

Welding Handbook, AWS

Some Applications

Resistance welding Electrode to Spark Plug Nickel (typically Inconel 600) Sheath Copper Core Electrode Weld to Steel Plug Body Chiu, R, “Spark Plug with Copper Cored Ground Electrode and a Process of Welding the Electrode to a Spark Plug Shell” US Patent 5,530,313 Jan 25, 1996

Welding of a current collector in a Ni-Cd Coil Wound Battery Nakamaru, H, et al, “Cylindrical Storage Battery” US Patent 6,013,389 Jan 11, 2000 Ni Cd Separator Nickel strip (3&4) resistance spot welded to nickel plated steel collector plate (7&8)

Method For Replacing Blade Tip of Directionally Solidified and Single Crystal Blades (Tips to prevent leakage of Compressed Air Between Blade and Shroud) Rene N5 (single Crystal) Rene 142 Dir. Solidified Blade Cross Section Resistance Weld Air Holes Bewlay, B, et al “Method for Replacing Blade Tips of Directionally Solidified and Single Crystal Turbine Blades”, US Patent 5,822,852 Oct 20, 1998