titanium. resistance welding lesson objectives when you finish this lesson you will understand:...
TRANSCRIPT
![Page 1: Titanium. Resistance Welding Lesson Objectives When you finish this lesson you will understand: Learning Activities 1.View Slides; 2.Read Notes, 3.Listen](https://reader035.vdocuments.net/reader035/viewer/2022081603/56649e115503460f94afcf09/html5/thumbnails/1.jpg)
Titanium
![Page 2: Titanium. Resistance Welding Lesson Objectives When you finish this lesson you will understand: Learning Activities 1.View Slides; 2.Read Notes, 3.Listen](https://reader035.vdocuments.net/reader035/viewer/2022081603/56649e115503460f94afcf09/html5/thumbnails/2.jpg)
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
![Page 3: Titanium. Resistance Welding Lesson Objectives When you finish this lesson you will understand: Learning Activities 1.View Slides; 2.Read Notes, 3.Listen](https://reader035.vdocuments.net/reader035/viewer/2022081603/56649e115503460f94afcf09/html5/thumbnails/3.jpg)
Donachie, Titanium,ASM, 1988
![Page 4: Titanium. Resistance Welding Lesson Objectives When you finish this lesson you will understand: Learning Activities 1.View Slides; 2.Read Notes, 3.Listen](https://reader035.vdocuments.net/reader035/viewer/2022081603/56649e115503460f94afcf09/html5/thumbnails/4.jpg)
Donachie, Titanium,ASM, 1988
![Page 5: Titanium. Resistance Welding Lesson Objectives When you finish this lesson you will understand: Learning Activities 1.View Slides; 2.Read Notes, 3.Listen](https://reader035.vdocuments.net/reader035/viewer/2022081603/56649e115503460f94afcf09/html5/thumbnails/5.jpg)
Unique Properties• Light Weight• Excellent Corrosion Resistance• Strong tightly adherent oxide• High strength-to-weight ratio
Applications• Chemical Industry• Aerospace Industry• Marine Fields• Medical Applications
T i t a n i u mM e l t i n g
p o i n t3 0 3 5 F1 6 7 0 C
B o i l i n gP o i n t
5 9 0 0 F3 2 6 0 C
C o e f f i c i e n to f
E x p a n s i o n
F/in/in67.4
D e n s i t y 3in/lb163.0
U T S 3 0 k s i P u r e T i2 0 0 k s i A l l o y s
D u c t i l i t y 1 5 – 2 5 %
Phases in Pure Titanium• Alpha {hcp} < 1620F (880C)• Beta {bcc} > 1620F
![Page 6: Titanium. Resistance Welding Lesson Objectives When you finish this lesson you will understand: Learning Activities 1.View Slides; 2.Read Notes, 3.Listen](https://reader035.vdocuments.net/reader035/viewer/2022081603/56649e115503460f94afcf09/html5/thumbnails/6.jpg)
Classification of Titanium Alloys• Alpha & near Alpha Alloys• Alpha-Beta Alloys• Metastable Beta Alloys
AWS Welding Handbook
![Page 7: Titanium. Resistance Welding Lesson Objectives When you finish this lesson you will understand: Learning Activities 1.View Slides; 2.Read Notes, 3.Listen](https://reader035.vdocuments.net/reader035/viewer/2022081603/56649e115503460f94afcf09/html5/thumbnails/7.jpg)
AWS Welding Handbook
Can Lead to BrittlenessEspecially in welds (see below)
![Page 8: Titanium. Resistance Welding Lesson Objectives When you finish this lesson you will understand: Learning Activities 1.View Slides; 2.Read Notes, 3.Listen](https://reader035.vdocuments.net/reader035/viewer/2022081603/56649e115503460f94afcf09/html5/thumbnails/8.jpg)
AWS Welding Handbook
![Page 9: Titanium. Resistance Welding Lesson Objectives When you finish this lesson you will understand: Learning Activities 1.View Slides; 2.Read Notes, 3.Listen](https://reader035.vdocuments.net/reader035/viewer/2022081603/56649e115503460f94afcf09/html5/thumbnails/9.jpg)
Commercially Pure Titanium• Yield Strengths 35-80 ksi (interstitial O, N, C)
Alpha Titanium Alloys• Not heat treated to increase strength• Used for moderate elevated-temp strength and creep resistance
Near-alpha Alloys• Contain small amount of Beta stabilizers• Marginally heat treatable• Most contain Si for improved high temp properties
![Page 10: Titanium. Resistance Welding Lesson Objectives When you finish this lesson you will understand: Learning Activities 1.View Slides; 2.Read Notes, 3.Listen](https://reader035.vdocuments.net/reader035/viewer/2022081603/56649e115503460f94afcf09/html5/thumbnails/10.jpg)
Alpha-Beta Alloys (e.g. Ti-6Al-4V)• Mixture of Alpha & Beta• Annealed or Solution heat treated and aged• Outstanding strength to density ratio in heat treated condition• Excellent fracture toughness when annealed
Metastable Titanium Alloys• Contain high percentage of Beta stabilizing elements• Slow transformation - air cooling gives 100% Beta• Aging precipitates of fine Alpha can occur• Aging give strength but ductility and fracture toughness sacrificed• Frequently used for fasteners and springs
![Page 11: Titanium. Resistance Welding Lesson Objectives When you finish this lesson you will understand: Learning Activities 1.View Slides; 2.Read Notes, 3.Listen](https://reader035.vdocuments.net/reader035/viewer/2022081603/56649e115503460f94afcf09/html5/thumbnails/11.jpg)
Applications Using Titanium Alloys
For more information about applications see:http://www.titanium.org/GIsec2a.htm
![Page 12: Titanium. Resistance Welding Lesson Objectives When you finish this lesson you will understand: Learning Activities 1.View Slides; 2.Read Notes, 3.Listen](https://reader035.vdocuments.net/reader035/viewer/2022081603/56649e115503460f94afcf09/html5/thumbnails/12.jpg)
General Weld Problems
Oxygen Contamination Cracking• Oxygen > 3000ppm = WM & HAZ Cracking• Alpha (hcp) particularly susceptible• Removal of surface oxide film recommended • Gas shielding generally recommended (especially for seam welds)
Degree of Oxidation• Silver (mild oxidation)• Straw• Blue• White (severe oxidation - weld problems likely)
![Page 13: Titanium. Resistance Welding Lesson Objectives When you finish this lesson you will understand: Learning Activities 1.View Slides; 2.Read Notes, 3.Listen](https://reader035.vdocuments.net/reader035/viewer/2022081603/56649e115503460f94afcf09/html5/thumbnails/13.jpg)
General Weld Problems
Iron Contamination CrackingIron particle dissolve into surface causing loss of :• Corrosion• Embrittlement (when sufficient iron)
Prevention• Avoid steel fabrication near titanium fabrication• Avoid airborne dust• Avoid tools used for both Fe and Ti• Scratch Brush just prior to welding• Use clean gloves for handling
Http://www.twi.co.uk/bestprac/jobknol/jk24.html
![Page 14: Titanium. Resistance Welding Lesson Objectives When you finish this lesson you will understand: Learning Activities 1.View Slides; 2.Read Notes, 3.Listen](https://reader035.vdocuments.net/reader035/viewer/2022081603/56649e115503460f94afcf09/html5/thumbnails/14.jpg)
General Weld Problems
Hydrogen Embrittlement• Precipitation of titanium hydrides
• Hydrogen > 200ppm can cause problems• Use low moisture shielding gas
AWS Welding Handbook
![Page 15: Titanium. Resistance Welding Lesson Objectives When you finish this lesson you will understand: Learning Activities 1.View Slides; 2.Read Notes, 3.Listen](https://reader035.vdocuments.net/reader035/viewer/2022081603/56649e115503460f94afcf09/html5/thumbnails/15.jpg)
Example of Hydride Formation in Resistance Seam Weld
% H
ydri
de
Co
atin
g
Days
100
0500
2 days– no hydrides
43 days-at toe
227 days-1/2 around
450 days-Full around
25 ppm Hydrogen
2056 ppm hydrogenH
Toosky, R. “Evaluation of Titanium Hydride Formation in Resistance Seam Welded Dissimilar Titanium Joints”, Boeing Co., 1998
![Page 16: Titanium. Resistance Welding Lesson Objectives When you finish this lesson you will understand: Learning Activities 1.View Slides; 2.Read Notes, 3.Listen](https://reader035.vdocuments.net/reader035/viewer/2022081603/56649e115503460f94afcf09/html5/thumbnails/16.jpg)
Toosky, R. “Evaluation of Titanium Hydride Formation in Resistance Seam Welded Dissimilar Titanium Joints”, Boeing Co., 1998
Seam Weld Start, Nugget Pull-Out
![Page 17: Titanium. Resistance Welding Lesson Objectives When you finish this lesson you will understand: Learning Activities 1.View Slides; 2.Read Notes, 3.Listen](https://reader035.vdocuments.net/reader035/viewer/2022081603/56649e115503460f94afcf09/html5/thumbnails/17.jpg)
General Weld Problems
Porosity• H & O partitioned between solidifying dendrites• Micropores form when diatomic gas overcomes head pressure
AWS Welding Handbook
• Mircopores coalesce to form macropores• To keep O & H out of weld pool, clean & degrease
![Page 18: Titanium. Resistance Welding Lesson Objectives When you finish this lesson you will understand: Learning Activities 1.View Slides; 2.Read Notes, 3.Listen](https://reader035.vdocuments.net/reader035/viewer/2022081603/56649e115503460f94afcf09/html5/thumbnails/18.jpg)
AWS Welding Handbook
General Weld Problems
Ductility Dip• Alpha-beta alloys containing Nb rather than V more susceptible• Alpha films at prior beta boundaries more susceptible
Niobium Containing
• Material in HAZ with these peak Temp can experience Dip•Cracks are intergranular• Believed to be caused by volumetric difference during transformation
![Page 19: Titanium. Resistance Welding Lesson Objectives When you finish this lesson you will understand: Learning Activities 1.View Slides; 2.Read Notes, 3.Listen](https://reader035.vdocuments.net/reader035/viewer/2022081603/56649e115503460f94afcf09/html5/thumbnails/19.jpg)
Resistance Spot Welding• Surface Cleaning - Mechanical or Chemical {HF-HNO3}
• To lower surface resistance to below 50 microhms• To keep Titanium Oxide out of weld metal - embrittlement
• Handle with gloves• Store in low-humidity less than 48 hours• Higher resistivity for Alloys than steel = lower current
• Pure Ti can use SS Schedule•Class 2 Electrodes with 3 in radius spherical face• Gas shielding not required for spot welds
AWS Welding Handbook
Same Scheduleas SS for Pure Titanium, But Not For alloys
![Page 20: Titanium. Resistance Welding Lesson Objectives When you finish this lesson you will understand: Learning Activities 1.View Slides; 2.Read Notes, 3.Listen](https://reader035.vdocuments.net/reader035/viewer/2022081603/56649e115503460f94afcf09/html5/thumbnails/20.jpg)
AWS Welding Handbook
Schedule for Two Typical Alloys
![Page 21: Titanium. Resistance Welding Lesson Objectives When you finish this lesson you will understand: Learning Activities 1.View Slides; 2.Read Notes, 3.Listen](https://reader035.vdocuments.net/reader035/viewer/2022081603/56649e115503460f94afcf09/html5/thumbnails/21.jpg)
AWS Welding Handbook
Equiaxed Grains
Columnar Grains due to Effect of Alloys
![Page 22: Titanium. Resistance Welding Lesson Objectives When you finish this lesson you will understand: Learning Activities 1.View Slides; 2.Read Notes, 3.Listen](https://reader035.vdocuments.net/reader035/viewer/2022081603/56649e115503460f94afcf09/html5/thumbnails/22.jpg)
Resistance Seam Welding
AWS Welding Handbook
• Same Cleaning procedures as spot welding• Class 2 Electrode Wheels with radius face = wheel radius• Inert shielding gas recommended
• Electrode Force and Welding Current slightly higher than for spot welds in the same material
![Page 23: Titanium. Resistance Welding Lesson Objectives When you finish this lesson you will understand: Learning Activities 1.View Slides; 2.Read Notes, 3.Listen](https://reader035.vdocuments.net/reader035/viewer/2022081603/56649e115503460f94afcf09/html5/thumbnails/23.jpg)
Flash Welding Titanium
• Use machine capacities similar to that for steel• Gas Shielding not absolutely necessary but recommended
(Titanium Oxidizes rapidly)• Use fast flashing rates & shorter flashing times than steel
(minimize weld contamination)• Lower upset force than for steel• Flashing and upset distances slightly less than for steel
Flash Welding Has Been Done on Following:• Commercially Pure Ti• Ti-6Al-4V• Ti-8Al-1Mo-1V• Ti-5Al-2.5Sn
• Ti-6Al-2Sn-4Zr-2Mo• Ti-6Al-2Sn-4Zr-6Mo
Info from AWS and Titanium Industries Inc.
![Page 24: Titanium. Resistance Welding Lesson Objectives When you finish this lesson you will understand: Learning Activities 1.View Slides; 2.Read Notes, 3.Listen](https://reader035.vdocuments.net/reader035/viewer/2022081603/56649e115503460f94afcf09/html5/thumbnails/24.jpg)
SomeTitanium Welding
Applications
![Page 25: Titanium. Resistance Welding Lesson Objectives When you finish this lesson you will understand: Learning Activities 1.View Slides; 2.Read Notes, 3.Listen](https://reader035.vdocuments.net/reader035/viewer/2022081603/56649e115503460f94afcf09/html5/thumbnails/25.jpg)
Froes, FH, et al, “Non-Aerospace Applications of Titanium” Feb 1998, TMS
![Page 26: Titanium. Resistance Welding Lesson Objectives When you finish this lesson you will understand: Learning Activities 1.View Slides; 2.Read Notes, 3.Listen](https://reader035.vdocuments.net/reader035/viewer/2022081603/56649e115503460f94afcf09/html5/thumbnails/26.jpg)
SAAB 340 Aero Engine Shroud constructed from commercially pure titanium using resistance, spot and TIG welding. http://www.swantec.com/industry.htm
![Page 27: Titanium. Resistance Welding Lesson Objectives When you finish this lesson you will understand: Learning Activities 1.View Slides; 2.Read Notes, 3.Listen](https://reader035.vdocuments.net/reader035/viewer/2022081603/56649e115503460f94afcf09/html5/thumbnails/27.jpg)
Welding Battery Connectors for Implantable Medical Device
Electrodes
Shield Gas (Ar) Tube
Battery Case
Battery Case Top Feed Through Contacting Pin(glass sealed in case top)
Battery Tab
Weld Conditions1000 amps40 msec3.5 kgrams
Weld Combinations (inch)0.018 Ti tab to 0.035 Nb pin0.018 Ti tab to 0.020 Mo pin0.018 Ti tab to 0.020 Ta pin0.004 Ni tab to 0.020 Mo pin
Berkowitz, F, et al, “Implantable Medical Device With High Reliability Electrical Connection using Reactive Metals” US Patent 5,712,462 Jan 27, 1998
![Page 28: Titanium. Resistance Welding Lesson Objectives When you finish this lesson you will understand: Learning Activities 1.View Slides; 2.Read Notes, 3.Listen](https://reader035.vdocuments.net/reader035/viewer/2022081603/56649e115503460f94afcf09/html5/thumbnails/28.jpg)
Resistance Weld Ti Alloy HoneycombStructures for High Speed Civil Transport
(Requirement 72,000 hours @ 350F)(Al-Li max use temp = 225F)
Weld
Heat Treat1675-1825 F
15 min – 4 hours
Weld between Ti 6242S face sheet and Beta 21S honeycomb low heat treatment – Low mechanical Boundary Present
Weld with heat treatment – good properties
El-Soudani, S, “Process for Enhancing the Bond Strength of Resistance Welded Joints Between Titanium Alloy Articles” US Patent 5,830,289 Nov 3, 1998