AMPTIAC is a DOD Information Analysis Center Adminis tered by the Defense Information Sys tems Agency, Defense Technical Information Center

Special Issue:

Ships Navy Experts Explainthe Newest Material &Structural Technologies

The issue you hold in your hands has been 14 months in themaking. It began with a simple idea: turn the spotlight on theage-old art of building ships. We wanted to show the excitingnew technologies that are offering novel materials for ship con-struction, changing the way ships are built, and indeed creatingone of the most fundamental shifts in Navy combatants sincesteel replaced wood.

This simple mission turnedout to be much more complex.The project underwent a num-ber of different iterations, butfinally settled in and cametogether. It has been a labor oflove for yours truly, for I reallydo believe that even though air-planes and tanks often grab thespotlight, Navy ships are still the most challenging structuraland materials engineering systems fielded in today’s military.Nothing has the complexity, impact, size, and sheer force of afighting vessel, nor can many things capture the imagination inquite the same way.

So here it is, finally, and I am thankful that it is done. Notjust because it is off my desk and I can get on to the next proj-ect, but we are proud because AMPTIAC has compiled some-thing that probably has not existed before: an overview of thenewest technologies being incorporated into structures andmaterials for use aboard Navy combatants. And the people pro-viding the perspective are the experts at the Office of NavalResearch, NSWC-Carderock, and the Naval Research Lab. Youwon’t find this level of detail, variety, and expert contentfocused on this subject anywhere else.

That all being said, there is one critical feature of this publi-cation that needs some attention: the DOD center behind it.Some of you out there have been reading this publication forseven years now. You undoubtedly remember about two yearsago when we shifted over to our current layout format and full

color reproduction. You also have probably noticed that we arepublishing these large special issues fairly often. It is all a partof our mission to bring you the most in-depth, focused, andtechnologically exciting coverage of Defense materials and pro-cessing advances available anywhere.

But the side effect of the more noticeable and attention-grabbing Quarterly, is thatAMPTIAC itself has lost someattention. The reality is that thecenter has grown with numer-ous projects, focused reports,and database efforts over thepast few years, but there aremany out there that may readthis publication and not evenknow that the center exists.

We want to put more emphasis on the other efforts AMPTIAC is involved in, and let our customers and potentialcustomers know that we are here for you. We help with ques-tions, assist in materials selection, and provide consultation ona variety of materials and processing-related issues. We havemore than 210,000 DOD technical reports in our library anddirect access to hundreds of thousands more throughout DOD,DOE, NASA, and other US Government agencies. We havedozens of focused reports tailored to specific technology areasand many more compiling vast amounts of data into hand-book-style resources.

The basic message here is to take note of this magazine, readit, and enjoy. But if you think AMPTIAC is just the Quarterly,Think Again.

Wade BabcockEditor-in-Chief

Editorial: There’s More to AMPTIAC

than the Quarterly

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The AMPTIAC Quarterly, Volume 7, Number 3

INTRODUCTIONLighter, stronger, faster: This mantra drives structural materialsresearch and development for Navy systems. Ships that can bequickly deployed, carry larger payloads, reliably withstand theassaults of high sea states, and travel safely through harm’s wayare the ultimate goal of the scientists and engineers working onadvanced materials and the technologies for building them. Onemeans of achieving lighter, stronger, and faster ships and sub-marines is through the introduction of materials with specificproperty improvements including titanium and aluminumalloys, and higher strength steels. Effectively exploiting theseadvanced materials for ship construction requires developingeffective joining technologies, and friction stir welding (FSW) isan important part of this program.

FSW is a rapidly maturing solid state joining process thatoffers significant benefits over conventional joining processes.Invented by The Welding Institute (TWI) in 1991, FSW uses acombination of frictional heating and compressive loading tojoin metal plates that are butted against each other and tightlyclamped to the anvil of the machine.

The process, shown schematically in Figure 1, is initiated byrotating a welding tool (consisting of a shoulder and pin assem-

bly) at speeds up to severalhundred revolutions perminute (rpm) before it is low-ered into contact with the

plates to be joined. A vertical force (z-axis load) is applied per-pendicularly to the joint line, driving the rotating pin into thework piece. Frictional heat is generated at the top surface of theworkpiece under the FSW tool shoulder, and in the base mate-rial at the interface with the pin. For steels and other highermelting temperature alloys, a small-diameter hole is pre-drilledin the joint line to lessen the forces acting on the welding toolduring the plunge.

After sufficient dwell time to allow for homogeneous heatingand softening of the material, a lateral force (x-axis load) isapplied in the direction of travel. Both z- and x-axis loads acton the rotating welding tool as it traverses along the joint line,sweeping the softened material along the periphery of the pinand depositing it in the tool’s wake. This “stirring” action, alongwith the pressure and restraining forces induced by both thetool and fixturing, creates a heavily deformed region of materi-al which upon cooling defines a strong, metallurgical joint thatis fine-grained with no entrapped oxides or gas porosity.Characteristics that make solid state joining attractive areincluded in Table 1.

Friction stir welding of relatively low-melting temperaturematerials, such as alloys of aluminum and magnesium, hasmatured significantly and is being adopted by the aerospacecommunity. For example, NASA’s Marshall Space Flight Centerplans to use FSW for constructing Al-Li external fuel tanks, andEclipse Aviation has used FSW in the fabrication of jet aircraft.

The Navy is interested in extending thistechnology to shipbuilding and optimiz-ing it for joining naval materials, such ascarbon steels, stainless steels, titaniumalloys and nickel aluminum bronze.

FSW FOR SHIPBUILDINGFor future naval construction, emerginghigher strength, stiffness, and toughnesssteels and stainless steels are of interest.High strength, low alloy (HSLA) steelsand AL-6XN are currently being investi-gated. HSLA-65 steel is an alternative toDH-36 for aircraft carrier construction.

Maria Posada, Jennifer P. Nguyen, David R. Forrest, Johnnie J. DeLoachWelding and NDE Branch

Robert DeNaleMetals Department

Survivability, Structures, and Materials Directorate Carderock Division, Naval Surface Warfare Center

West Bethesda, MD

13

ab

c d

X

Y

Z

Figure 1. Schematic of FSW Process (left) and a Photo of an Actual FSW Tool (right)(Photo courtesy of University of South Carolina)

With improved property-to-weight ratios, HSLA-65 will theo-retically enable thinner-gauge sections to be used, resulting inlighter weight designs. (Please see the accompanying article byCzyryca, et. al. in this issue.) AL-6XN is a high-toughness, non-magnetic, super-austenitic stainless steel being evaluated as astructural material for Advanced Double Hull (ADH) surfacecombatants. (Please see the accompanying article by Beach inthis issue.)

In order to exploit the improved properties of these advancedsteels, advanced joining technologies will also be required.Conventional welding techniques applied to large steel plateswith thin gauge sections result in unacceptable levels of distor-tion in the final product that require expensive flame-straighten-ing or rework efforts. For stainless steels, weld distortion isexpected to be even greater than for carbon steels due to lowerthermal conductivity and higher thermal expansion. Costs asso-ciated with distortion correction can be high; for the USSArleigh Burke (DDG 51)-class ship (Figure 2), flame straighten-ing consumes significant labor costs for each ship construct-ed.[1] Considering other factors affected by flame straighteningoperations, such as material costs, interruption of other trades,and increased fitting time, the total cost of not controlling dis-tortion can reach approximately $3.4 million per ship for con-ventional steel construction and is expected to be greater ifaustenitic stainless steels are used.

Another significant challenge that FSW should overcome is the generation of hexavalent chromium (Cr6+), a known carcinogen. Conventional welding technologies used on stain-less steel alloys require melting the workpiece, and consequent-ly generate hexavalent chromium in fumes. The OccupationalSafety and Health Administration (OSHA) is planning toreduce workers’ permissible Cr6+ exposure limit to 0.5µg/m3.Data collected by a joint Navy/Industry task group showed thatCr6+ levels generated during arc welding of both carbon steeland stainless steel exceed the proposed OSHA limit. Theserequirements will significantly increase fabrication costs; theNavy estimated that the cost of complying with the new Cr6+

requirement could reach $80M per year for US Navy ship con-struction after a one time $30M implementation cost.

THE R&D PROGRAMIn response to these challenges, the Navy is investigatingadvanced joining methods, including FSW for joining of carbonand austenitic stainless steels. The overall program includes sci-ence and technology directed toward advanced equipment devel-opment, tool design and tool material development, weldingprocess parameter optimization, and understanding and predict-ing microstructural and mechanical property evolution duringjoining.

As part of these efforts, the Office of Naval Research’s (ONR)Manufacturing Technology (MANTECH) office investigatedfriction stir welding of 2519 aluminum for the Marine Corps’Advanced Amphibious Assault Vehicle (AAAV).[2] The FSWdemonstration projects successfully met ballistic, productivity,and distortion requirements that could not be obtained withconventional arc welding. The initial results of steel FSW trials,including weld evaluation and demonstration projects conduct-ed, are presented here.

Friction Stir Weld EvaluationsThe quality and mechanical properties of steel friction stirweldments were evaluated through metallography, hardnessmeasurements, chemical analysis and mechanical testing. Thefollowing paragraphs describe general trends and observationsfound in DH-36, HSLA-65, AL-6XN and 304L stainless steelfriction stir welds.

DH-36 Weld Evaluation A typical FSW cross-sectional micro-graph and corresponding hardness map are shown in Figure 3. Ingeneral, friction stir welds in most metals have three microstruc-turally distinct regions: the stir zone (SZ) along the weld center-line, a swirl region within the stir zone, and a heat-affected zone(HAZ) surrounding the stir zone and extending to the base metal[3, 4]. In some cases a fourth thermal-mechanically affected zone

Figure 2. USS Arleigh Burke (DDG 51).

The AMPTIAC Quarterly, Volume 7, Number 314

Table 1. Characteristics of Solid State Joining.• Minimization of fume generation since the heat

generated during this process remains below the melting temperature of the material

• Reduced distortion• The ability to form strong joints without filler wire• Reduced joint preparation and post-weld clean-up• Reduced post-weld inspection and rework• Various inherent user- and environmentally-friendly

properties, such as the ability to be automated

(TMAZ) can be present, as indicated in Figure 3. In DH-36,hardness measurements increase from the base metal through theHAZ into the SZ. The peak hardness corresponds to the swirlregion within the SZ. While this general hardness profile wasobserved for all the conditions studied, specific trends wereobserved to be functions of travel speed. As the travel speedincreased (1) the width of the SZ and HAZs decreased, (2) peakhardness increased, (3) yield strength and ultimate tensile strengthincreased, and (4) ductility as measured by percent elongationdecreased.

Figure 4 shows tensile properties as a function of travel speed.Substantial overmatching was noted within the stir zone of 0.25inch thick welds, and to a lesser extent in 0.5 inch thick weld.Ductility in the stir zone was greatly reduced in 0.25 inch thickplates and toughness values were lower for 0.5 inch thick welds.Bulk chemical analysis of DH-36 showed a residual amount ofmaterial left behind in the weld region by the pin tool as itwears. (Numbers indicated {kJ/in} above the tensile strength

data points are a measure of heat imparted during the weld.Closed diamond and square markers are for tests on 0.25 inchDH-36; open markers are tests on 0.5 inch HSLA-65.)

HSLA-65 Weld Evaluation Consistent with DH-36, HSLA-65can be friction stir welded–although the resulting structuresand properties differ. Friction stir welded sections from 0.25inch to 0.5 inch thick have been successfully produced, atspeeds on the order of 5 inches/minute (ipm). Figure 5 showsthe overall structure of an HSLA-65 friction stir weld (in 0.5inch plate) compared to that of an HSLA steel conventional arcweld (in 1.0 inch plate). (Note that the conventional weldshown in Figure 5 is actually HSLA-100, a different alloy com-position but one for which hardness maps were available. [5])Although both welds have similar gross features (a weld zone, aheat-affected zone, and the base metal), their microstructuresand properties are very different. Within the stir zone of thefriction stir weld a swirl region shows evidence of vertical flow

Figure 4. Plot Showing Increase in Yield Strength and Decrease in Percent Elongation as a Function of Travel Speed.

The AMPTIAC Quarterly, Volume 7, Number 3 15

Figure 3. DH-36 FSW Cross-section Showing the Four Microstructurally Distinct Regions and Corresponding Hardness Values (Vickers Microhardness).

0 5 10 15 20Travel Speed (ipm)

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Plate Yield Strength: 62 ksi

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(67 kJ/in)

(69 kJ/in)

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of material. The 0.5 inch thick friction stir weld was produced intwo passes; the first on what is now the bottom of the photo-graph, and the second on the top. The 1.0 inch thick conven-tional weld was produced using approximately 25 successive weldpasses starting at the bottom of a “V”-shaped notch. (It is possi-ble however, to use fewer passes to complete the weld).

Hardness maps of weld cross sections are shown in Figure 6.In this case there is a softening of the metal in the HAZ aroundthe stir zone of the friction stir weld, although this does notalways occur. In general, the stir zone is stronger and harder thanthe base metal, but not as tough. There is additional hardeningin the stir zone of the first pass, just outside the HAZ of the sec-ond pass. (This can be seen along the bottom of the FSW hard-ness map in Figure 6 at 15,000 and 29,000 microns.) The con-ventional weld HAZ is harder than the weld or base metal.

Friction stir welds in HSLA-65 have also been compared withthose in DH-36, an alloy with higher C, Ni, and Cr that hasbeen used extensively in naval structural applications. The hard-ness profile of an FSW in HSLA-65 differs dramatically fromthat of DH-36 and other typical steels. In this evaluation, the

hardness profile of HSLA-65 softened in the HAZ region and thepeak hardness in the stir zone was not significantly higher thanthe base metal hardness. (The difference in hardness from thebase metal to peak hardness was approximately two times greaterin DH-36 than in HSLA-65.) The stir zone’s yield and ultimatetensile stresses were fairly comparable to the base metal propertiesand it maintained good ductility. At strength levels of 94 ksi forthe HSLA-65 and 107 for the DH-36, charpy impact energies ofthe HSLA-65 material were significantly higher than those of theDH-36 (Figure 7).

AL-6XN Weld Evaluation Bulk chemical analysis of AL-6XN weldsshowed pin tool material pick-up, particularly in the plunge area.The hardness profile for AL-6XN was similar to that of DH-36 inwhich the hardness increased from the base metal through theHAZ and into the SZ. The SZ properties significantly over-matched the base metal properties with a significant reduction inelongation. [6] Centerline sigma phase (a hard, brittle intermetal-lic phase) was observed in 0.25 inch thick plate and not in the 0.5inch thick plate (Figure 8). Energy dispersive spectroscopy analysis

Figure 5. Optical Micrographs Comparing the Major Features of an FSW and a Conventional Arc Weld(Transverse Cross Sections).

Friction Stir Weld Conventional Arc Weld

Figure 6. The Hardness Maps of the FSW and Conventional Welds in Figure 5 Show Significantly Different Patterns.

Friction Stir Weld Conventional Arc Weld [5]

The AMPTIAC Quarterly, Volume 7, Number 316

Swirl Region Stir ZoneHAZ

Base Metal

HAZ Weld Nugget

10000750050002500

0

0 10000 20000 30000 40000Distance (µm)

Dist

ance

(µm

)

170 180 190 200 210 220 230 240 250Vickers Microhardness

Vickers Microhardness

216 326 436

of various regions of the weldment demonstrated that (1) the swirlregion contained tungsten particles (i.e., pin tool material), (2)banded regions outside the weld area had distinct concentrationdifferences of Mo, Cr, and Ni (compositional elements of thesigma phase), and (3) intergranular precipitation of sigma phasewas observed in bands with higher concentrations of Mo, Cr, andNi. In the 0.5 inch thick plate, the stir zone exhibited excellenttoughness, equivalent to that of the base metal.

304L Weld Evaluation Similar to DH-36 and AL-6XN, bulkchemical analysis showed pin tool material pick-up within theweld region of the 304L. Its hardness profile showed little variancein hardness across the various weld regions, and the stir zone prop-erties exceeded both the base metal and weld metal requirementswhile maintaining high ductility (~65% elongation). [3]

Technology DevelopmentThis series of evaluations have demonstrated the feasibility andpromise of FSW for joining steel plate compositions used innaval construction. They have also illustrated the challenges thatmust be addressed in order to successfully exploit this revolu-tionary technology. The Navy is committed to understanding,describing and simulating the myriad technical issues being

addressed by the Navy laboratory and warfare centers, universi-ties and industry. These include specifically the mechanisms ofsevere deformation, influences of initial workpiece condition(compositionally and microstructurally), influences of tool mate-rials and geometries, effects of welding parameters on mechanicaland microstructural properties, and many others.

The initial technological focus was motivated by evolvingNavy warfare requirements and increasingly stringent environ-mental regulations that create a need for improved weldingprocesses to fabricate military and commercial structures usingferrous materials. The focus was expanded to include com-bined Navy/industry interest in the development for self-react-ing FSW tool technology for 2519, 2219, and 2195 aluminumalloys, as well as AL-6XN and HSLA-65 steels. This expansionwas motivated by three FSW technology related developments.They were:• adjustable, self-reacting FSW pin tool capabilities

patented by MTS [7]• the emergence of FSW technology advancements with

increasing potential benefits to the near term success of theAdvanced Amphibious Assault Vehicle (AAAV) Program,

• commercial interest in similar FSW technology advance-ments for aerospace applications. The approach has included advanced equipment develop-

ment, tool material evaluation, welding process parameter devel-opment, mechanical property measurements, and metallurgicalevaluation. Various materials were successfully welded and eval-uated namely, 0.125 inch thick A588, 0.25 inch thick 304Lstainless steel, 0.25 inch and 0.5 inch thick DH-36, 0.25 inchand 0.5 inch thick HSLA-65, 0.25 inch and 0.5 inch thick AL-6XN, and 0.320 inch and 1 inch thick 2519, 2219, and 2195Al alloys. Development of welding process parameters for DH-36, HSLA-65, AL-6XN, and the Al alloys as a function of pintool type (fixed and adjustable self-reacting) and joining method(single-sided {welded only from one side of the plate}, double-sided {welded from both sides of the plate}, overlapped plates,and tapered welds {joining two plates of different thickness})continues.

Two projects were used to demonstrate the specific applicabil-

Figure 7. Friction Stir Welds of HSLA-65 Show the Potential ofSignificantly Tougher Behavior.

Figure 8. Micrographs Showing (a) Centerline Sigma Phase (Dark Strip) Observed in 0.25 Inch Thick Plate and(b) No Centerline Sigma Phase Present in 0.5 Inch Thick Plate.

The AMPTIAC Quarterly, Volume 7, Number 3 17

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HSLA-65 weld 1 HSLA-65 weld 2 DH-36 weld

a b

ity of the FSW process. The first was a comparative distortionstudy between conventional arc and friction stir welded plates,and the second was an assessment of shock loading tolerance(which was also the first reported dynamic fracture test of a steelfriction stir weld).

Post Weld Distortion Study Results HSLA-65 plates with a thick-ness of 0.25 inch were used for the distortion studies.Conventional arc and friction stir welded plates were fabricatedat Bath Iron Works and the University of South Carolina,respectively. All welds used a square butt joint configurationand were fabricated in the flat position. The conventional arcwelds were fabricated using two distinct welding conditions.Case 1 consisted of a double-pass, two-sided submerged arcweld (SAW) and Case 2 consisted of a single-pass, single-sidedgas metal arc weld (GMAW). Comparisons between measure-ments taken before (baseline) and after welding indicated thatthe friction stir welded plates displayed significantly lowerangular distortion as compared to arc-welded plates [8]. Figure9 shows baseline and post weld measurements for FSW, SAW,and GMAW plates.

Shock Hole Test Results A shock hole test panel was fabricatedby friction stir welding two, 0.5 inch thick HSLA-65 plates,each 26 inches wide and 50 inches long; the longest length

corresponding to the weld direction. After machining, the 50inch diameter test panel was bolted to a paddle wheel test fix-ture (schematically shown in Figure 10) and tested underwaterwith an explosive charge. Results indicated that the friction stirwelded HSLA-65 test panel had shock holing resistance equiv-alent to the base metal HSLA-65 test panel under identical testconditions. [9] Figure 11 shows the resulting deformation ofboth the base and friction stir welded plate after testing.

FUTURE EFFORTSFriction stir welding is proving to be a viable option for joininghigh strength steels. The Navy’s goal is to friction stir weld up to0.5 inch thick HSLA-65 steel for an uninterrupted length of 80feet at a travel speed that would make FSW competitive withcurrent conventional arc welding techniques. However, impor-tant technical challenges remain due to the higher temperaturesand forces involved which cause accelerated degradation of toolassemblies and severely limit productivity. A two-prongedapproach is being used to meet the immediate needs of gettingthe process to the shipyard and developing the understandingthat will enable wider, more effective exploitation of this tremen-dous technological opportunity.

A shipyard implementation plan is under development toaddress critical technology areas, including:• novel methods to improve process efficiency, including

processes such as thermal management to enhance tool life• joint design optimization, including fit-up requirements and

tool change out methods• improved modeling capabilities validated for materials of

interest to the Navy• quality assurance and non-destructive evaluation techniques

to identify common welding discontinuities and confirm thatthese discontinuities can be detected by traditional NDEtechniques

• material and structural certification to determine mechanicalproperties and fracture performance, fatigue life, structuralperformance, and corrosion behavior

• process certification requirements• production implementation which includes technology trans-

fer and training, performing procedure qualification, and per-forming operator qualification.

Figure 9. Comparison of Baseline (Grid) and Post-weld (Solid) Distortion Measurements of (a) FSW,(b) SAW, and (c) GMAW Plates.

The AMPTIAC Quarterly, Volume 7, Number 318

HSLA-65 Test Panel

Charge

Figure 10. Schematic of Shock Hole Test Fixture.

a b cY (inches)

Z (inches)

Z (inches)

Z (inches)

Y (inches) Y (inches)

Concurrent with shipyard implementation, importantresearch and development continues to build the base for under-standing and exploiting the critical mechanisms at work inFSW. This work is aimed at identifying and predicting optimalprocessing conditions, including tool design and tool material.Alloys and microstructures that are most amenable to FSW maybe predicted, then further development will tailor welded jointsfor high performance and robust responses to a wide spectrumof loading and environmental conditions. Emerging simulationand predictive modeling capability will further guide FSWdevelopments and enable design engineers to confidently exploitthis revolutionary technology.

SUMMARY AND CONCLUSIONSFriction stir welding is a transformational, solid state joiningtechnology offering the potential for high performance andaffordability for naval applications. The initial efforts demon-strating the Navy’s interest and commitment to develop thepractical processes and systems for shipyard implementation ofFSW have been described here. The underlying technologyenabling longer-term payoff for an extended array of materialsand component requirements for FSW has also been demon-strated. The ONR-sponsored Dual Use Science andTechnology program successfully demonstrated the feasibilityof FSW in steels and stainless steels, as well as the utility of self-adjusting pin tool designs. The demonstration projects showedreduced angular distortion in FSW compared with convention-ally arc welded plates and excellent shock holing resistance(equivalent to that of the base metal) from underwater testing.Future efforts focus on building the understanding needed tocritically assess the viability of, and gain the maximum benefitfrom, FSW.

ACKNOWLEDGEMENTSThis work was sponsored by the ONR Seaborne StructuralMetals Program, Julie A. Christodoulou Program Manager.

REFERENCES[1] C. Conrardy, and R. Dull, “Control of Distortion in ThinShip Panels,” Journal of Ship Production, v. 13, no. 2, pp. 83-92 [2] T. Trapp and T. Stotler, “Friction Stir Welding of theAdvanced Amphibious Assault Vehicle,” presented at the 2002American Welding Society International Welding & FabricatingExposition, Chicago, IL, March 2002[3] M. Posada, J. DeLoach, A.P. Reynolds, M. Skinner, and J.Halpin, “Friction Stir Weld Evaluation of Steel and StainlessSteel Weldments”, Proceedings of the Symposium on FrictionStir Welding and Processing, eds. K.V. Jata, M.W. Mahoney,R.S. Mishra, S.L. Semiatin, and D.P. Field, TMS 2001,Indianapolis, Indiana, 5-7 November 2001, pp. 159-171[4] T.J. Lienert, W.L. Stellwag, JR., B.B. Grimmett, and R.W.Warke, “Friction Stir Welding Studies on Mild Steel”, TheWelding Journal, Research Supplement, v. 82, no. 1, 1s – 9s(January 2003)[5] D.W. Moon, R.W. Fonda and G. Spanos, “Microstructureand Property Evolution in HSLA-100 Steel Welds Fabricatedwith New Ultra Low Carbon Filler Metals”, The WeldingJournal, Research Supplement, v. 79, no. 10, 278s-285s (October,2000) [6] M. Posada, J. DeLoach, A.P. Reynolds, and J.P. Halpin,“Mechanical Property and Microstructural Evaluation of FrictionStir Welded AL-6XN”, Proceedings of the 6th InternationalConference on Trends in Welding Research, eds. S.A. David, T.DebRoy, J.C. Lippold, H.B. Smartt, and J.M. Vitek, PineMountain, Georgia, 15-19 April 2002, pp. 307-311

Figure 11. Photo of FSW Plate After Testing and Comparative Deformation Plot of Base- and Friction Stir Welded-HSLA-65 Plate.

The AMPTIAC Quarterly, Volume 7, Number 3 19

HSLA-65, FSW: Along Weld

HSLA-65, FSW: Perpendicular to Weld

HSLA-65 Baseplate

Distance Across Diameter (in.)

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.)12

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The AMPTIAC Quarterly, Volume 7, Number 320

[7] J. Halpin and R. Edwards, “Friction Stir WeldingTechnology Commercialization for High Strength StructuralAlloys”, Final Report for Agreement N00014-00-3-008 betweenThe Office of Naval Research and MTS Systems Corporation,10 December 2002[8] Campbell et. al., “Welding Head”, US Patent No.US6,1999,745 B1, dated March 13, 2001

[9] M. Posada, J. DeLoach, A.P. Reynolds, J. Halpin,“Evaluation of Friction Stir Welded HSLA-65”, to be publishedin proceedings for the 4th International Symposium of FrictionStir Welding, Park City, Utah, 14-16 May 2003

Ms. Maria Posada is a materials engineer in the Welding and NDE branch at the Naval Surface Warfare Center.Ms. Posada received her BS in Metallurgical Engineering (1996) and an MS in Metallurgical and MaterialsEngineering (1998) from the University of Texas at El Paso. She is currently leading a Navy effort to evaluate theFriction Stir Welding (FSW) process that may provide an affordable alternative to conventional arc welding of steelsand nonmagnetic stainless steels. Ms. Posada has contributed to numerous technical publications and technical pre-sentations in this area.

Ms. Jennifer Nguyen is a materials engineer in the Welding and NDE branch at Naval Surface Warfare Center,Carderock Division. Ms. Nguyen received her BS in Materials Science and the Biomedical Engineering (2002) fromJohns Hopkins University. She is pursing her PhD in materials science at the University of Maryland-College Park.

Dr. David Forrest is a materials engineer with the Welding and NDE group at the Naval Surface Warfare Center(Carderock). He is involved with projects relating to the friction stir welding, the laser fabrication of HSLA-65, and themathematical modeling of welding. He has been a consultant in advanced materials technology with BaverstamAssociates, and has worked in plant operation and research positions in the steel industry between 1978 and 1999,with Republic Steel, Bethlehem Steel, and Allegheny Ludlum Corp. He specialized in microstructural analysis, com-putational and statistical methods for optimizing mechanical properties, and in the mathematical modeling of metal-lurgical processes. He completed his doctorate degree at MIT and is also President of the Institute for MolecularManufacturing, a non-profit organization.

Robert DeNale is head of the Metals Department at the Naval Surface Warfare Center, Carderock Division. Hisareas of scientific and engineering interest include welding, nondestructive evaluation and high strength steel castingmetallurgy. He has authored numerous publications and US Navy technical reports. He has been awarded 7 USpatents, edited two books, and made more than 50 presentations at professional society meetings.

Mr. DeLoach is the Head of the Welding & NDE Branch at the Naval Surface Warfare Center. He received his BS in Materials Science and Engineering from Brown University and his Masters of Materials Science andEngineering from Johns Hopkins University. Mr. DeLoach has twenty years of experience in the materials and welding areas. He has more than 100 technical contributions (papers, publications, etc.) in the areas of welding,materials, and nondestructive evaluation.