Magnetically Impelled Arc Butt (MIAB)

165 Pages·2008·3 MB·English

by  David Phillips

MAGNETICALLY IMPELLED ARC BUTT (MIAB) WELDING OF CHROMIUM-
PLATED STEEL TUBULAR COMPONENTS UTILIZING ARC VOLTAGE
MONITORING TECHNIQUES

DISSERTATION

Presented in Partial Fulfillment of the Requirements for the Degree Doctor of
Philosophy in the Graduate School of The Ohio State University

By
David H. Phillips, M.S.W.E
*****

The Ohio State University
2008

Dissertation Committee:
Professor Charley Albright, Advisor Approved by
Professor Dave Dickinson
_________________________________
Professor John Lippold Advisor
Welding Engineering Graduate Program
ABSTRACT

Magnetically Impelled Arc Butt (MIAB) welding is a forge welding technique
which generates uniform heating at the joint through rapid rotation of an arc. This
rotation results from forces imposed on the arc by an external magnetic field. MIAB
welding is used extensively in Europe, but seldom utilized in the United States. The
MIAB equipment is robust and relatively simple in design, and requires low upset
pressures compared to processes like Friction welding.
In the automotive industry, tubular construction offers many advantages due
to the rigidity, light weight, and materials savings that tubes provide. In the case of
automotive suspension components, tubes may be chromium-plated on the ID to
reduce the erosive effects of a special damping fluid. Welding these tubes using the
MIAB welding process offers unique technical challenges, but with potential for
significant cost reduction vs. other welding options such as Friction welding. Based
on published literature, this research project represented the first attempt to MIAB
weld chromium-plated steel tubes, and to utilize voltage monitoring techniques to
assess weld quality.
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Optical and SEM microscopy, tensile testing, and an ID bend test technique
were all used to assess the integrity of the MIAB weldments. This analysis revealed
the potential for chromium-enriched regions, most likely chromium oxides, to
become trapped at the weld interface resulting in severe degradation of mechanical
properties. Voltage plots generated during the arc monitoring were analyzed and
correlated with Design of Experiment (DOE) statistical results and high speed video
images.
The DOE results revealed the individual and interactive importance of arc
heating (referred to as level II) time, expulsion (referred to as level III) current, and
arc gap on weld quality. Correlations were established between specific features of
the arc voltage plots and weld quality. Based on arc physics theory, it was proposed
that these three variables affected arc pressure, which contributed to improved
expulsion and a reduction in chromium entrapment in the joint. As a result,
feasibility for MIAB welding chrome-plated suspension components was established,
and voltage monitoring methodology was identified as a potential quality control
technique for producing this joint.

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Dedicated to my parents, whose guidance and unwavering support has always
propelled me through the difficult times in my life, and my sister Barbara, who has
been my “guiding light” throughout adulthood

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ACKNOWLEDGMENTS

I would like to thank my advisor, Professor Charley Albright, for first
providing me with the opportunity to pursue a PhD, and then supporting and
encouraging me throughout the process, while always allowing me some measure of
independence.
I am grateful to my good friend, Dr. Anthony Ananthanarayanan, for all of his
moral, technical, and financial support throughout most of my PhD studies, and for
allowing me the flexibility to pursue this degree while simultaneously working at
Delphi.
I am thankful to Delphi for providing most of the financial support during my
PhD. A special thank you goes out to Tom McCray and Jule Hegwood, who spent
countless hours helping me with the DOE and statistical analysis aspect of this
research.
I would also like to thank Dr. Vladimir Kachinskiy who provided valuable
technical insight.

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VITA

March 6, 1961 ……………..................... Born – Chillicothe, Ohio
1984 ……………………………………. B.S. Welding Engineering, The Ohio State
University
1986 ……………………………………. M.S. Welding Engineering, The Ohio State
University
1986 - 1987 …………………………….. Corporate Welding Engineer
Motor Wheel Corporation
Lansing, Michigan

1987 - 1992 ……………………………... Welding Engineer
GE Aircraft Engines
Cincinnati, Ohio

1992 - 2004 …………………………….. Market Leader, Aerospace
Edison Welding Institute
Columbus, Ohio

2004 – present …………………………... Senior Weld Research Engineer
Delphi
Kettering, Ohio

PUBLICATIONS

1. D.H. Phillips, W.A. Baeslack III, “Selection and Weldability of Advanced
Titanium-Base Alloys”, ASM Handbook Volume 6, Welding, Brazing, and
Soldering, 524-528, (1993)
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2. W.A. Baeslack III, D.H. Phillips, G.K. Scarr, “Characterization of the Weld Heat
Affected Zone in an Alpha-Two Titanium Aluminide”, Materials Characterization,
Vol. 28, no. 1, 61-73 (1992)

3. W.A. Baeslack III, D.H. Phillips, C. English, A.P. Woodfield, “Inertia-Friction
Welding of an Advanced Rapidly Solidified Titanium Alloy”, Journal of Materials
Science Letters 10, 1401-1408 (1991)

4. L.C. Mallory, W.A. Baeslack III, D.H. Phillips, “Evolution of the Weld Heat-
Affected Zone Microstructure in a Ti-48Al-2Cr-2Nb Gamma Titanium Aluminide”,
Journal of Materials Science Letters 13, 1061-1065 (1994)

5. L.C. Mallory, W.A. Baeslack III, D.H. Phillips, T.J. Kelly, “Gas Tungsten Arc
Welding of a Ti-48Al-2Cr-2Nb Gamma Titanium Aluminide”, Titanium ’92 Science
and Technology, Proceedings, Symposium at 7th World Titanium Conference, San
Diego, Vol.2; 29 June-2 July 1992, 1115-1122, (1993)

6. S.A. David, J.A. Horton, G.M. Goodwin, D.H. Phillips, R.W. Reed, “Weldability
and Microstructure of a Titanium Aluminide”, Welding Journal, Vol. 69, no. 4, 133s-
140s, (April, 1990)

7. M.C. Juhas et. al., “Interface Characteristics of Solid Phase Welds Between Ti-
6Al-2Sn-4Zr-2Mo-0.1Si and 14Al-21Nb Titanium Aluminide” Titanium ’92 Science
and Technology, Proceedings, Symposium at 7th World Titanium Conference, San
Diego, Vol.2; 29 June-2 July 1992, 1453-1460, (1993)

8. K.N. Hou, et. al., “An Electron Microscopy Study of Inertia-Friction Welds in Ti-
48Al-2Cr-2Nb Gamma Titanium Aluminide”, International Trends in Welding
Science and Technology, Gatlinburg, Tennessee, 1-5 June 1992, 1135-1137, (1993)

FIELDS OF STUDY

Major Field: Welding Engineering

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TABLE OF CONTENTS

ABSTRACT..................................................................................................................................................ii
ACKNOWLEDGMENTS.............................................................................................................................v
VITA..............................................................................................................................................................vi
LIST OF FIGURES......................................................................................................................................x
LIST OF TABLES.....................................................................................................................................xvi

CHAPTERS:

1. INTRODUCTION....................................................................................................................................1
1.1 MIAB WELD PROCESS DESCRIPTION...........................................................................................1
1.1.1 MIAB Welding Principles....................................................................................................3
1.1.2 Comparison to other Welding Processes.............................................................................6
1.2 ARC MONITORING SYSTEMS.........................................................................................................7
1.3 MOTIVATION FOR WELDING CHROMIUM-PLATED STEEL TUBES..................................................7
1.4 OBJECTIVES OF THE RESEARCH....................................................................................................9
2. TECHNICAL REVIEW........................................................................................................................10
2.1 MAGNETIC FLUX AT THE MIAB WELD JOINT.............................................................................10
2.2 ARC BEHAVIOR AT THE MIAB WELD JOINT...............................................................................12
2.3 ARC ROTATION VELOCITY.........................................................................................................19
2.4 MIAB WELDING OF NON-FERROUS MATERIALS........................................................................23
2.5 SHIELDING GAS EFFECTS............................................................................................................25
2.6 HEAT FLOW IN THE MIAB WELDING PROCESSES.......................................................................28
2.7 MIAB APPLICATIONS.................................................................................................................30
2.8 GENERAL WELDABILITY OF CHROMIUM-PLATED STEEL............................................................32
3. EXPERIMENTAL PROCEDURE.......................................................................................................36
3.1 MIAB EQUIPMENT.....................................................................................................................37
3.2 DESCRIPTION OF COMPONENTS AND WELD SET-UP...................................................................41
3.3 MECHANICAL TEST METHODS....................................................................................................42
3.4 METALLURGICAL EVALUATION METHODS.................................................................................45
3.5 HIGH SPEED VIDEO MONITORING...............................................................................................47
3.6 DOE METHODOLOGY.................................................................................................................49
3.7 ARC MONITORING.......................................................................................................................54

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4. RESULTS................................................................................................................................................55
4.1 METALLURGICAL ANALYSIS.......................................................................................................56
4.2 MECHANICAL ANALYSIS............................................................................................................63
4.3 ANODE/CATHODE EXPERIMENTS................................................................................................65
4.4 L12 DOE BASED ON ID BEND TEST CRACK LENGTH................................................................66
4.5 ARC MONITORING PLOTS...........................................................................................................70
4.6 HIGH SPEED VIDEO IMAGES.......................................................................................................72
5. DISCUSSION.........................................................................................................................................74
5.1 METALLURGICAL ANALYSIS.......................................................................................................74
5.1.1 Optical Microscopy of Tubes without Chromium-plating..................................................74
5.1.2 Optical Microscopy of Tubes with Chromium-plating.......................................................75
5.1.3 SEM Fractography of MIAB Welds with Chromium-plating.............................................76
5.1.4 Microhardness Testing......................................................................................................77
5.2 MECHANICAL ANALYSIS............................................................................................................78
5.3 ANODE/CATHODE (JOINT POSITION WITHIN THE MAGNETIC FIELD) EXPERIMENTS....................79
5.4 L12 DOE....................................................................................................................................82
5.4.1 Individual Effect of Variables on ID Bend Test Crack Length...........................................83
5.4.2 Interactive Effect of Variables on ID Bend Test Crack Length..........................................84
5.4.3 Effect of Variables and the Concept of Arc Force and Arc Pressure................................87
5.4.4 Effect of Arc Gap Setting...................................................................................................95
5.5 HIGH SPEED VIDEO IMAGE INTERPRETATION.............................................................................98
5.6 ANALYSIS OF ARC MONITORING VOLTAGE PLOTS - CORRELATION WITH DOE RESULTS........100
5.6.1 Analysis of Voltage Plots – Interpretation of Characteristic Features.............................100
5.6.2 Analysis of Voltage Plots – Effect of Level II Time...........................................................102
5.6.3 Analysis of Voltage Plots - Effect of Level III Current....................................................106
5.6.4 Analysis of Voltage Plots - Effect of Gap Setting.............................................................109
5.6.5 Summary of Arc Monitoring Voltage Plot Analysis.........................................................112
5.7 CONCLUSIONS.....................................................................................................................113
5.8 FUTURE WORK....................................................................................................................115
5.8.1 Further Characterization of Fracture Surfaces...............................................................115
5.8.2 Shielding Gas Effects.......................................................................................................115
5.8.3 Anode/Cathode Experiments...........................................................................................116
5.8.4 Effect of Initial Gap Setting.............................................................................................116
5.8.5 Ratio of Solid-State Weld Interface Length to Overall Weld Interface Length................117
5.8.6 Further Analysis of Weld Voltage “Signatures”.............................................................117
5.8.7 Continuation of High Speed Video and Arc Pressure Analysis.......................................118
REFERENCES..........................................................................................................................................119
APPENDIX A............................................................................................................................................122
A.1 22 MM COMPONENT - RESULTS................................................................................................122
A.1.1 Metallurgical Analysis.....................................................................................................122
A.1.2 Mechanical Analysis........................................................................................................126
A.1.3 L16 DOE Based on Weld Interface Length Measurement...............................................129
A.2 22 MM COMPONENT – DISCUSSION..........................................................................................133
A.2.1 Metallurgical Analysis.....................................................................................................133
A.2.2 Mechanical Analysis........................................................................................................134
A.2.3 L16 DOE.........................................................................................................................135
A.3 ARC MONITORING VOLTAGE PLOTS........................................................................................138
A.4 40 MM CHROME-PLATED COMPONENT PRELIMINARY DEVELOPMENT RAW DATA.................145

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LIST OF FIGURES

Figure Page

1 Basic Schematic of the MIAB Welding Process……………………………...2

2 Interaction Between Current and an Applied Magnetic Field ………..............3

3 Aligned Magnetic Flux Lines Create Force on Conductor……………………4

4 Radial Component of Arc Current Affects Arc Movement……………….......5

5 Arc Monitoring System Detects GMAW Defect………………………….......8

6 Method for Measuring Magnetic Flux Density……………………………...11

7 Maximum Flux Density Occurs at 5 mm from Pipe Surface………………...11

8 Melting Patterns of Thick-Walled Tube Reveal Melting on ID……………..14

9 Magnetic Flux in Tube-to-Plate Joint Pushes Arc Outward…………………16

10 Arc Trace on Tube End Shows Movement from OD to ID………………….17

11 Magnetic Arc Blow due to Tube Geometry Effects…………………………18

12 Spontaneous Magnetization of Iron as a Function of Temperature………….18

13 Movement of the Arc Toward Tube OD…………………………………......19

14 Speed of Arc Affected by Heating (1) and Arc Gap (2)……………………..20

15 Arc Velocity vs. Time Plot Reveals Three Distinct Regions………………...22

16 Variations in Flux Density at the Joint………………………………………24
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