Nickel Base Alloys

Resistance Welding

Lesson ObjectivesWhen you finish this lesson you will understand:•

Learning Activities1. View Slides; 2. Read Notes, 3. Listen to lecture4. 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 (ThO2)• Ni-Ti Shape Memory Alloys

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

AWS Welding Handbook

AWS Welding HandbookNote Variation Pure Fe = 9.7

pure SS ppt 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 AlloysGamma 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 SteelFor Lower Strength Materials• Same Force LevelsFor High Strength (at Elevated Temp)• Higher Forces

a. Expulsion = Force too lowb. Electrode Mushroom = Force too high

Because of wide variations in propertiesExact welding conditions vary widely

Spot Welding

Resistance Welding Manual, RWMA

For thin material up to 0.06”If tip sticking go to 10o

For heavier material 0.06-0.125”

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 WeldingFrequency Converter

AWS Welding handbook

Spot Weld Defects

Hot Cracking• lower S&P• forge force

Coring• higher R in GB• Constitutional Liquation• Reduce particles in HAZSulfur HAZ Surface Cracking

•Oil, Grease, Marking Pencil on Surface

Resistance Welding Manual, RWMA

Projection WeldingSeldom 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 FrictionDrive Wheel

Roll Spot Weld

Overlapping SeamWeld

Continuous SeamWeld

[Reference: Welding Handbook, Volume 2, p.553, AWS]

Intermittent Pulse, Intermittent Roll, Forge Force PossibleNo Intermittent Roll, No Forge Possible

Class 1 or 2 RollsBurnished to PreventSticking

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 UpsetIf flashing current is cut off before upset, oxide forms at centerline

Resistance Welding Manual, RWMA

Welding Handbook, AWS

SomeApplications

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

ResistanceWeld

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