3. Experimental Methods
Reference: [1] J. W. Elmer and D. D. Kautz, “Fundamentals of Friction Welding,” in ASMHandbook, Vol. 6, Welding, Brazing, and Soldering, Materials Park, OH: ASM International,1993, pp. 150–155.
Friction and Fusion Dissimilar Welding of Stainless Steel to 1018 Steel
Nathan Switzner1, Zhenzhen Yu1, Michael Eff2, Arthur Fonseca1, Stephen Liu1
1. Colorado School of Mines, 1500 Illinois St., Golden, CO 804012. EWI, 1250 Arthur E. Adams Dr., Columbus, OH 43221
2. Objectives Compare properties of welds made by friction and fusionprocesses with the down-selected parameters. Evaluate the heat affected zone (HAZ) microstructure andits impact on mechanical properties.
Friction welds had a narrower HAZ in the1018 than the fusion weld as observed in thehardness map.
Friction welds had fine Widmanstatten ferriteand 2nd phase in the 1018 steel near the bondline.
Fusion welds had fine equiaxed ferrite and2nd phase near the bond line due to the multi-pass process.
5. Discussion
Acknowledgements:The American Welding Society (AWS) isgratefully acknowledged for fellowshipsupport of this research. Dr. T. Lienert fromLANL is thanked for his technical support, Dr.J. Gould, T. Stottler and EWI for frictionwelding, D. Chirichello and Exova Lab forhardness testing, and the CSM Welding Centerstudents and faculty.
1. Problem StatementAs a solid-state process, friction welding avoids solidification and segregationproblems which are typically associated with fusion welding of dissimilar metals. [1] It is essential to identify microstructure-property relationships to compare frictionand fusion welding.
Friction welds:• 304L stainless steel and 1018 steel bars of25 mm diameter & 100 mm length.
• Equipment: MTI 120 Inertia Welder Fusion weld:
• Multi-pass bead-on-plate flux cored arcweld to deposit 309L on 25 mm thick 1018steel plate (welded on end grain forcomparison with friction weld).
• Equipment: Miller Axcess 450 in DCEN,heat input of 1.3 kJ/mm for high deposition.
Digital image correlation (DIC) method wasused to monitor strain during tensile testing.
Hardness mapping was performed using aStruers Durascan Automatic Tester.
4. ResultsMicrostructure
304L stainless bar
flash
partially deformed
zone
deformed zone
fine Widman-statten ferrite & 2nd phase
intercritical austenite
transformed to ferrite & 2nd phase
Fusion Weld
309L
Tensile Tests
interface
reheated fine grain HAZ
intercritical HAZ
intercritical austenite
transformed to ferrite & 2nd phase
ferrite & pearlitede-carburized zone, then fine
ferrite & 2nd
phase in 1018
Vic
kers
Har
dnes
s
304L Stainless
1018 Steel
StrainBond LineFracture
in 1018
1018 steel bar (2% nital etch)
subcritical HAZ
309L weld deposit (Kallings #2 etch)
1018 steel plate
5 mmfusion line HAZ
bond lineHAZ
Microhardness
5 mm
304L 10181018
For all dissimilar welds, necking andfinal fracture was in the 1018 steel.
304L bar
R 6 mm
10 m
m
x2 6 mm
3 mm
bond line
1018 bar
25 m
m g
age
leng
th
flash
2 mmtensile bars
metallographic sample5 mm
6. Conclusions Friction welds had higher tensile strength
than fusion welds. Tensile fracture occurred in the soft HAZ of
the 1018 for both dissimilar welds. The fusion weld resulted in a de-carburized
zone in the 1018, not found in friction welds.
5 mm 5 mm
1018 1018
309L
ferrite & pearlite
1018base metal
Friction Weld
Digital image correlation (DIC) example for friction weld tensile test
tensile bars
Fusion Weld Approx. 5 mm wide
soft zone in 1018
Friction Weld Approx. 2.5 mm wide soft zone in 1018 Work-hardening in 304L near interface
309L
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