THE NATIONAL SHIPBUILDING RESEARCH PROGRAM · accomplished in accordance with MIL-STD-271 (Ref. 4).Destructive examination specimens were prepared and tested in accordance with AWS

SHIP PRODUCTION COMMITTEEFACILITIES AND ENVIRONMENTAL EFFECTSSURFACE PREPARATION AND COATINGSDESIGN/PRODUCTION INTEGRATIONHUMAN RESOURCE INNOVATIONMARINE INDUSTRY STANDARDSWELDINGINDUSTRIAL ENGINEERINGEDUCATION AND TRAINING

THE NATIONALSHIPBUILDINGRESEARCHPROGRAM

August 1987NSRP 0281

1987 Ship Production Symposium

Paper No. 19: Evaluationof Commercially Available WetWelding Electrodes for PotentialRepair of U.S. Navy Ships

U.S. DEPARTMENT OF THE NAVYCARDEROCK DIVISION,NAVAL SURFACE WARFARE CENTER

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SOCIETY OF NAVAL ARCHITECTS AND MARINE ENGINEERS

Evaluation of Commercially Available Wet Welding No. 19Electrodes for Potential Repair of U.S. Navy ShipsThomas C. West, Visitor, Welding Engineering Services, and Gene Mitchell, Visitor, Naval Sea Command

ABSTRACT

As part of a program to determinethe viability of underwater wet weldingfor repair of U. S. Navy surface ships,eight commercially available shieldedmetal arc wet welding electrodes wereevaluated by a series of screeningtests. Two E7014 “type” electrodes pro-vided superior results and were used forwelding procedure qualification testingon ASTM A-36 steel with a carbon equiva-lent of 0.35. Qualification testingincluded visual, liquid penetrant andradiographic inspection, as well as bendtesting, reduced section tensile test-ing, all-weld-metal tensile testing,Charpy impact testing, macroscopic exam-ination, hardness testing, and chemicalanalyses. The wet welding was performedin the vertical, overhead and horizontalpositions. The welding took place atseven and thirty-three feet of seawater.

Nondestructive and destructive testresults show that both electrodes exceedthe requirements of American WeldingSociety specification for underwaterwelding, AWS D3.6 (Ref. 2) Type B. Weldquality and strength were found to beapproximately on a par with welds madein an air environment. Weldment ductil-ity and toughness were appreciably lowerthan would be expected of air welds.

1.0 INTRODUCTION

The term “wet welding” refers towet hyperbaric welding (welding in thewet at ambient pressures greater thanone atmosphere) as opposed to dry hyper-baric welding (sometimes referred to asdry chamber welding). In wet welding,there is no mechanical barrier separat-ing the welding arc from the surroundingwater; and the only physical barrier arethe bubbles being generated by the heatof welding and decomposition of theelectrode flux and waterproofing materi-als. The work covered by this paper, aswell as all comments contained herein,are in reference to wet welding usingthe shielded metal arc (covered elec-trode) welding process.

Until the late nineteen sixtiesand early nineteen seventies, wet weld-ing was considered appropriate only fornon-critical applications, such asemergency temporary repairs and salvagework. Until the late nineteen seven-ties, some ship fabrication documentsconsidered wet welds to be only sixty-percent efficient. Private industrybegan producing structural quality wetwelds, for permanent repair to offshorestructures, in the early nineteen sev-enties. These welds were produced bydiving companies using their own in-house, proprietary wet welding elec-trodes; the welds developed the fullstrength of the mild steel base metal,and thus were considered one hundredpercent efficient. However, weld metaltoughness, ductility and internal qual-ity were less than what would be ex-pected of welds made in a normal airenvironment; and base metal heat-affected-zone hardness was higher thanthat normally associated with weldsmade in a dry environment. Today,internal quality of wet welds has im-proved somewhat; but weld metal ductil-ity and toughness, and base metal heat-affected-zone hardness, are still noton a par with welds made in the dry.However, for commercial applications,wet welds have been shown to exhibitacceptable structural properties undera number of loading conditions.

Because of the success of wetwelding in the various commercial ap-plications, and the large costs asso-ciated with the drydocking of ships,the U. S. Navy has started a program toevaluate and, where appropriate, de-velop and implement underwater weldingfor repair of Navy ships. Both dryhabitzt and wet welding are encompassedin the program. The work describedherein represents a portion of theoverall program. Wet welding has beensuccessfully used in permanent and tem-porary repairs on ships and other com-mercial floating structures. The scopeof this work was as follows:

- Evaluation and comparison ofcommercially available wet weld-ing electrodes, to determine

19-1

those exhibiting superiorproperties.

- Performance of wet welding pro-cedure qualification testingusing those electrodes found tobe superior during the electrodeevaluation or screening tests.The qualification testing usedsteel produced to the require-ments of MIL-s-22698 (Ref. 5).

- Development of welding procedurespecifications based on thequalification welding performed.

2.0 PROGRAM TESTING AND EVALUATION

2.1 Facilities

Diving and welding facilities wereprovided by Global Divers and Contrac-tors of New Iberia, Louisiana; TheGlobal test tank is shown in Figure 1.The wet welding tank was 36 feet high,20 feet in diameter, and contained seawater. The filtering system maintainedclear water throughout the welding ope-rations. The air compressor and volumetank were adequate for the support oftwo welder/divers working at the sametime. The welding machines were both400 ampere Miller diesel driven genera-tors. FIGURE 1. Global Divers Test Tank

2.2 Materials and Examinations

The base metal consisted of bothhigh carbon equivalent (CE) and low CEsteel plate meeting the requirements ofMIL-S-22698. Mill certificates were ob-tained for each steel, and independentchemical analyses were also made. Thefollowing represents the properties ofthese steels:

*Carbon UTS YSSteel Thickness Equivalent KSI/MPa KSI/MPa Elongation

ASTM A36 3/8” 0.280 67.7/467 50.6/349 25%" 1/2” 0.376 67.6/466 47.7/329 29%" 3/4” 0.350 71.1/490 50.0/345 29%

DH 36 3/8” 0.449 80.0/552 60.0/414 25%" 1/2” 0.443 78.3/540 55.3/381 21%" 3/4” 0.435 77.7/536 60.3/416 25%

*CE = C + Mn/6 + (Cr + Mo + V)/5 + (CU + Ni)/15

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Six mild steel and two austeniticsteel electrodes were evaluated. Theelectrodes are identified by numbers 1through 8. All electrodes, except Num-ber 8, were 1/8” in diameter; ElectrodeNumber 8 was 5/32” in diameter. Elec-trode Numbers 1, 2, 3 and 8 were E7014“types”; Electrode Numbers 6 and 7 wereE6013 “types”; Electrode Number 4 wasE309-16; Electrode No. 5 was an E31O-16“type”.

All nondestructive examination wasaccomplished in accordance with MIL-STD-271 (Ref. 4). Destructive examinationspecimens were prepared and tested inaccordance with AWS B4.O (Ref. 1) andAWS D3.6.

2.3 Environmental Conditions

The temperature of the water in thetank ranged from 75F to 85F. Weldingwas accomplished at depths of 33 FSW and7 FSW. Visibility was excellent at alltimes. The divers’ breathing medium wasair. The pressure at depth was 14.7 PSIgage at 33 FSW, and 3.1 PSI gage at 7FSW . Allowable times at 33 FSW weredetermined using the 40-foot criteria ofthe U.S. Navy dive tables.

2.4 Test Plate Design & Testing

2.4.1 The eight commerciallyavailable wet welding electrodes wereinitially tested during the screeningtests. Based on these tests, two elec-trodes were chosen for qualificationtesting.

2.4.2 Screening tests. Allscreening tests were accomplished at a33 foot water depth using two welder/divers. This allowed duplication of alltests, reducing the chances of acceptingan electrode which would run successful-ly only when a unique style of weldingwas utilized. Test plates consisted ofcruciform specimens and grooved platespecimens, the design of which is shownin Figure 2. DH 36 steel, 3/8” thick,was used for the cruciform specimensfollowing the welding sequence shown inFigure 3. The object of the welding se-quence was to induce relatively highrestraint to allow determination of anypropensity for cracking in either theweld or base metal heat-affected-zone.The cruciform specimens were liquidpenetrant inspected after welding. Theywere then sectioned to provide two MACROsections, 1 1/2” from each end; theMACROS were sanded to a 120 grit finish,etched, and examined at a magnificationof 7x. The welding electrodes whichwere found acceptable were furtherevaluated using the grooved plates.

The grooved plates were prepared toallow both a vertical and an overheadweld to be made in each plate. Bothhigh CE (DH 36) and low CE (A36) steel

were used for the grooved plates. Afterwelding and visual inspection, theplates were liquid penetrant inspected,radiographed, and sectioned to providetwo MACROS and 12 face bend specimensfor each weld. The MACROs were pre-pared and evaluated as specified abovefor the cruciform MACROS. Four facebends were performed over radii of 6T,4T and 2T, T being the bend specimenthickness (3/8”). When four bendspassed the 6T bend test, four morespecimens were. then tested over the 4Tbend radius; success over the 4T bendradius warranted four additional bendsover the 2T bend radius. The 6T bendradius is specified by the AmericanWelding Society specification forunderwater welding AWS D3.6 for Type Bwelds, whereas the 2T radius is typicalof that specified for in-air surfacewelding and dry hyperbaric underwaterwelding.

The cruciform and grooved plateweldments were evaluated using the formshown in Figure 4; one of these formswas completed, for the vertical andoverhead positions, for each wet weld-ing electrode being evaluated. Thoseelectrodes with the highest totalscores were selected for qualificationtesting at 33 and 7 FSW respectively.As can be seen from the form shown inFigure 4, the “GRADING CRITERIA” speci-fies three grades for each type of test-- the lowest grade being one, and thehighest grade being three. The gradeis multiplied by the weight factor(indicates the relative importance ofthe specific evaluation criterion) toobtain the score for each test per-formed.

2.4.3 Qualification tests. Testplates consisted of 3/4” ASTM A36steel. Test plate X, which was 20”long, was used to obtain two reducedsection tensiles, four side bends, oneVICRO section with Vickers hardnessreadings, five weld metal Charpy impactspecimens, and five base metal heat-affected-zone Charpy impact specimens.Charpy impact test temperature was 28F.Test plate Y, which was 16” long, wasused to obtain two all-weld-metal ten-sile specimens and weld metal chemis-tries. Test plate X and Y designs areshown in Figure 5.

Each wet welding electrode, se-lected for qualification testing, wasqualification tested in accordance withthe following:

Position Test Plate Type Depth, FS?W

v x & Y 3 3 & 7H x 33OH x & Y 3 3 & 7

Accordingly, a total of nine butt welds(five for Test Plate X and four for

19-3

CRUCIFORM SPECIMEN

3 / 8 ”GROOVED PLATE SPECIMEN

FIGURE 2. Screening Test Plates

19-4

FIGURE 3. Typical Welding Sequence for Cruciform Specimen

Test Plate Y) were attempted for eachwet welding electrode chosen for quali-fication testing. Qualification testswere summarized using the form shown inFigure 6.

2.5 Test Results

2.5.1 Screening tests

2.5.1.1 Cruciform. All cruci-form were made using the high CE DH 36steel. Cruciform bead appearanceranged from good (Figures 7 and 8) topoor (Figures 9 and 10). The cruci-form were welded in the vertical andoverhead positions at a water depth of33 feet. Three layers of weld metalwere deposited in each corner (seeFigure 3).

Weldability, visual and liquidpenetrant inspection, and MACRO sec-tions were evaluated and graded usingthe form shown in Figure 4. Represen-tative photographs of the MACRO sec-tions are shown in Figures 11 through

19-5

18. Mild steel electrode Numbers 2, 6,7 and 8 were rejected based on welda-bility and surface appearance; each ofthe electrodes suffered arc outagesduring welding -- resulting in roughweld beads. Electrode Numbers 2, 6 and7 MACROS are shown in Figures 13, 17and 18. MACRO sections were not takenfrom the electrode No. 8 cruciform,since the irregularity of the weldbeads were obviously unacceptable. Theelectrode would hardly sustain an arc(see Figure 9) with the electrode nega-tive -- which is the polarity normallyused with the mild steel electrodes;when the polarity was changed to elec-trode positive (see Figure 10) , better,but unacceptable, results were ob-tained. The waterproof coating integ-rity of the electrode was poor, allow-ing some of the electrode flux coatingto dissolve in the water, which proba-bly caused most of the problems.

The austenitic stainless steelelectrodes, Numbers 4 ad 5, were re-jected based on longitudinal, center

WET WELDING SCREENING EVALUATION FORM

EVALUATION CRITERIAweight CRUCIFORM FILLET GROOVED PLATEFACTOR GRADE SCORE GRADE SCORE

11

Puddle control 1/ 1

Puddle visibility 1/ 1

Slag removal 1/ 1

Gen. visual weld appearance 1/ 1

I I 2 I N/A N/A IVisual Inspection 3/ 3

SCORE: weight factor x grade

TOTALSCORE Weld I.D. Number

* G P -Weld I.D. Number

Welder/diver

Position

● CF (cruciform fillet)● GP (grooved plate)

GRADING CRITERIA

pass(es)---loccas. pinhole---2 Meets N/S 0900-003-8000, Cl.

Neets N/S 0900-003-80001 Cl,Fair---2 Starts/stops,Good---3 None---3

Meets AWS D3.6, Type A---2Meets MIL-STD-248---3

2 2---1 3---

MIL-STD-248---1MIL -STD-248 ----2MIL-STD-248---3

Electrode Diameter, Brand & Type

Start Time (cruciform): Finish Time: Date :

Start Time (grooved

Name of Evaluator 6

Finish Time:.

plate) : Date :

Firm:

PLATE

I .

Y PLATE

FIGURE 5. Qualification Test Plates

bead, cracking. This cracking tendencywas most pronounced in the root pass ofthe welds. It is not known whetherthis cracking tendency is a result ofthe dilution by the carbon steel basemetal, or due to the small weld crosssection of the initial (root) passcoupled with high restraint and a knowntendency for hot cracking of the aus-tenitic stainless steels. The No. 5electrode did not show the cracking ten-dency during cruciform welding; however,

19-7

the cracking manifested itself throughthe entire thickness of the root passof the first grooved plate weld. As aresult, the grooved plate weld was notcompleted, and no further welding wasattempted using this electrode. Elec-trode No. 4 and No. 5 NACROS are shownin Figures 15 and 16.

No base metal or heat-affected-zonecracking was detected in any weldment byvisual or liquid penetrant inspection.

PROCEDURE QUALIFICATION TEST RESULTS

TYPE OF TEST TEST RESULTS OR ACCEPTANCE STANDARDS MET

Visual Inspection 1/ Test Plate X: Test Plate Y:

Test Plate X: Test Plate Y:



Side Bends 2/ .Fail. Locat.: UTS : Ys Elong.

wardness Values 2/ Avg. BM: Avg. IIAZ: Avg. WM:

Charpy-V-Notch 2/ A v g . / M i n . I I A Z : / Avg./Min. WM: ; /

AWM Tensile 3/ UTS : Ys : Elongation:c: Mn: Si: P: s: Cut Ni: MO :v: Cr: oxygen:

inspections. The most stringent acceptance standard passed shallbe recorded.

Electrode Brand, Diameter & Type:

Base Metal; Welding Position:

Name of Evaluator: Firm;

Weld I.D. Number: TEST PLATE

TEST PLATE

x:v.

Water Depth:

FIGURE 7. Electrode No. 1Vertical Fillet, 33 FSW


!- . .

FIGUPW 8. Electrode No. 3Overhead Fillet, 33 FSW

This is particularly significant forthe DH 36 steel, which had a carbonequivalent of 0.449. Neither was under-bead cracking observed on the MACROsurfaces when prepared to a 120 gritfinish and examined at a 7X magnifica-tion. However, upon closer examina-tion, all the mild steel weldments inthe DH 36 steel showed underbead crack-ing. This will be discussed in Section2.5.1.2 below.

Based on the cruciform scoring us-ing the form of Figure 4, ElectrodeNos. 1, 3 and 5 were chosen for furthertesting using grooved plates.

2.5.1.2 Grooved plates. The aus-tenitic stainless steel electrode, No.5, was eliminated as described in

FIGURE 10. Electrode No. 8Vertical Fillet, 33 FSWElectrode Positive

2.5.1.1 above based on root pass crack-ing.

The two mild steel electrodes, Nos.1 and 3, were further evaluaked using3/8” high CE DH 36 steel grooved plates.With respect to visual inspection, liq-uid Penetrant inspection, bend testing,and MACRO evaluation, both ElectrodeNos. 1 and 3 produced similar results.With respect to radiographic inspection,Electrode No. 3 generslly produced acleaner weld due to a significantlylower porosity level. RepresentativeMACROS of these welds are shown inFigure 19.

Bend testing of the high CE (DH 36steel) grooved plate welds produced someinteresting results. Of the 16 6T bend

19-9


FIGURE 12. Electrode No. 1 FIGURE 14. Electrode No. 3Overhead Fillet, 33 FSW Overhead Fillet, 33 FSW

specimens tested for each electrode,only one specimen per electrode failedto pass the test; and these failureswere a result of a single linear indi-cation, slightly longer than 1/8”, whichwas clearly visible but did not “openup “ (crack-like indication, as opposedto a tear). Of the 16 4T bend specimenstested for each electrode, nine speci-mens failed for each electrode; althoughmost of these failures were fractures,a few had only small -- but rejectable-- linear indications. The significanceof these results is that all failureswere in the heat-affected-zone of thebase metal, which attests somewhat tothe integrity of the wet welds. How-ever, the failures caused some concernas to whether or not underbead cracking

19-10

was present, but had not been detectedin the MACRO evaluations. Underbeadcracking is usually predicted when wetwelding high CE steels (CE greater than0.40) using ferritic electrodes. Ac-cordingly, a cruciform MACRO and agrooved plate MACRO were prepared to a400 grit finish (the earlier finish was120 grit, which is normal for MACROexamination) , etched and re-examined.Underbead cracking, in the heat-affected-zone, was found in both sam-ples. Figure 20 shows two of theunderbead cracks in a cruciform MACRO.

As a result of the underbeadcracking problem with the DH 36 steel/ferritic electrode combination, thegrooved plate welds were repeated using


FIGURE 16. Electrode No. 5Overhead Fillet, 33 FSW

the low CE A36 steel plate. Thesetests show results similar to thoseobtained with the DH 36 steel groovedplates, except for the bend tests. Allthe 6T and 4T bends passed for Elec-trode Numbers 1 and 3. Eowever, noneof the 2T bends passed; these failuresoccurred in the weld metal -- as op-posed to the heat-affected-zone -- whenbent to an angle of approximately 30 to45 degrees.

2.5.1.3 Screening tests summaryand conclusions. Using the gradingsheet of Fiqure 4. the total score was109.67 for- Electrode Number 1 and115.29 for Electrode Number 3. Thehigher score for Electrcde Number 3 isa result of cleaner welds as shown by

FIGURE 17. Electrode No. 6Vertical Filletr 33 FSW

FIGURE 18. Electrode No. 7Overhead Fillet, 33 FSW

radiographic inspection; the Number 3electrode tended to produce less weldmetal porosity in all positions ofwelding. This was also confirmed inthe MACRO evaluations. Otherwise, thetwo electrodes tended to be fairlyequal in terms of weldability and over-all weld quality.

Both Electrode Numbers 1 and 3caused underbead cracking in the highCE DH 36 steel; this underbead crack-ing was found in both the cruciformsand the grooved plates. Physical evi-dence of the underbead cracking wasmanifested in the heat-affected-zonefailures of the bend tests. However,when used on the low CE ASTM A36 steelplater there was no evidence of the

19-11

underbead cracking, and all the bendsfor the low CE metal successfullypassed the 6T and 4T tests.

Both Electrode Numbers 1 and 3exceeded the bend test requirements ofAWS D3.6 fcr Type B welds, in that theysuccessfully passed testing over a 4Tbend radius (one-third smaller than the6T radius required by AWS D3.6). Also,each electrode occasionally met theClass 1 radiographic acceptance stan-dards of NAVSHIPS 0900-LP-O03-9000(Ref. 7), which are more stringentstandards than those of AWS D3.6 forType B or A Welds. Based on these testresults,and the fact that the MACROspecimens met the requirements of MIL-STD-248 (Ref. 3), both these electrodeswere considered suitable for weldingprocedure qualification testing.

b.

c.

d.

e.

FIGURE 19. Grooved Plate MACROS

A - Elect. No. 1, Vertical 33 FSWB - Elect. No. 1, Overhead 33 FSWc - Elect. No. 3, Vertical 33 FSWD - Elect. No. 3, Overhead 33 FSW

2.5.2 Qualification tests

2.5.2.1 Electrode Number 1.Qualification testing was performed forElectrode Number 1 as shown in Table I.The electrode number is the first digitof the specimen identification number.Maximum and minimum mechanical proper-ties are shown in Table II. Typicalcompleted welds are shown in Figures 21through 24 (weld nomenclatures areshown in Table I) . Electrode Number 1was found to consistently meet the fol-lowing conditions at *7 FSW and 33 FSW:

a. Radiographic acceptance stan-dards of AWS D3.6 for Type Bwelds.

DH 36 Steel, 17.5 X

Class 2 visual inspectionstandards of NAVSHIPS 0900-LP-003-8000, Ref. 6, (except asindicated below).

Class 1 liquid penetrant inspec-tion standards of NAVSHIPS 0900-LP-003-8000.

More stringent bend test re-quirement- (4T vs 6T) than thosespecified by AWS D3.6 for Type Bwelds.

Tensile strengths exceeding thatof the ASTM A36 base metal.

* Overhead position qualificationcould not be accomplished at 7 FSW.

FIGURE 21. Electrode No. 1Vertical Qualification33 FSW

19-12

in the overhead position at both waterdepths, such that one test plate (10Y-H-33 , Figure 24) failed to meet anysurface inspection acceptance stan-dards. The electrode also tended toundercut in the horizontal weldingposition, but to a lesser extent thanin the overhead position.


FIGURE 24. Electrode No. 1Overhead Qualification33 FSW

FIGURE 23. Electrode No. 1Horizontal Qualification33 FSW

Electrode Number 1 did not demon-strate the same degree of weldability at7 FSW as at 33 FSW. The electrode couldnot be qualified in the overhead posi-tion at 7 FSW due to the high crowned,narrow beads. The Y plate could not becompleted; the X plate was completed at7 FSW in the overhead position, and therough capping beads were ground offprior to radiographic inspection; how-ever, the weld failed the AWS D3.6 TypeB acceptance standards due to extensiveslag and lack of fusion.

Electrode Number 1 also demonstrat-ed significant undercutting tendencies

The waterproof coating of Elec-trode Number 1 is soft and must be pro-tected from the water until the elec-trode is ready for use. Accordingly,each electrode comes in an individualplastic bag, taped around the electrodestub end. This allows the stub to beinserted into the electrode holderprior to removing the bag. The bag canbe removed completely, or the electrodetip can be punched through the bag, al-lowing the bag to be pushed up aroundthe electrode toward the electrodeholder. The welder/divers found thebags to present visibility problemsunless completely removed. Since watersometimes leaked into the taped end ofthe bags, the in-water life of theelectrodes can be somewhat limited.The maximum water exposure time for theelectrodes was not determined; however,it was found that exposure (in the bag)overnight resulted in poor electrodeperformance.

Electrode Number 1 can be usedwith either the drag or the oscillationwelding technique; however, the oscil-lation technique (type of swirling mo-tion) seemed to produce better resultsand was essential in the overhead weld-ing position. The electrode depositeda fairly tenacious “sootyr’ substance atthe weld toes in the horizontal andoverhead positions; this had to be

19-13

removed prior to making the next weldpass. Slag removal was easy for theelectrode.

Electrode Number 1 can be de-scribed as a high deposition, moderate-ly easy to use wet welding electrode.Weld quality is good except for moder-ate porosity which easily meets therequirements of AWS D3.6 for Type Bwelds; this porosity is more pronouncedin the vertical position. The porositydoes not appear to be detrimental interms of the mechanical testing whichwas accomplished for the electrode.Overhead welding, at the seven footdepth, produced unacceptable weld beadprofiles.

2.5.2.2 Electrode Number 3.Qualification testing was performed forElectrode Number 3 as shown in Table I;maximum and minimum mechanical proper-ties are shown in Table II. The com-pleted welds are shown in Figures 25through 29 (weld nomenclatures areshown in Table I). Electrode Number 3was found to consistently meet the fol-lowing conditions at 7 FSW and 33 FSW:

a.

b.

c.

d.

Type B radiographic acceptancestandards of AWS D3.6.

Class 2 visual inspection stan-dards of NAVSHIPS 0900-LP-O03-8000.

Class 1 liquid penetrant in-spection standards of NAVSHIPS0900-LP-O03-8000.

More stringent bend test re-quirements(4T vs 6T) thanthose required by AWS D3.6 forType B welds.

FIGURE 25. Electrode No. 3Vertical Qualification33, FSW

19-14


e. Tensile strength exceeding thatof the ASTM A36 base metal.

Electrode Number 3 showed a de-creased weldability in the overheadposition at 7 FSW; as with ElectrodeNumber 1, the weld beads tended to benarrower and higher crowned than at 33FSW. However, both the X and Y plateswere successfully qualified in theoverhead position at 7 FSW. Radiographsof the X plate showed linear indica-tions at the weld toes in the root.Removal of backing strap showed “wagontrack” type slag, sometimes associatedwith root undercut. The weld was thenbackground and rewelded; radiographicinspection was again performed andshowed the weld to meet the acceptancestandards of AWS D3.6 for Type B welds.Therefore, at 7 FSW, Electrode Number 3may be considered qualified for platebutt welds in the overhead positiononly where the weld can be cleaned andwelded from the back side.

Electrode Number 3 had a paraffincoating over the primary waterproofcoating. The paraffin tended to “bloomout“ at the arc, reducing visibility.The welder/divers sometimes removed theparaffin by short circuiting me elec-trode for three or four seconds (caus-ing the electrode to heat up slightly)and sliding the entire layer of paraf-fin off the electrode. (The paraffinwas added by the electrode manufacturerafter the screening tests were complet-ed; it was added due to the reportedoxidation of the primary waterproofcoating, although the primary water-proof coating never failed to adequate-ly protect the electrode from thewater.)

Electrode Number 3 can be de-scribed as a high deposition, easy touse wet welding electrode. The overallweldability and puddle control wereslightly better than Electrode Number1, and weld porosity was significantlylower than that of Electrode Number 1.However, the mechanical properties Ofthe two electrodes were equivalent.Electrode Number 3 can be used witheither the drag or the oscillationtechnique. Electrode Number 3 had easyslag removal.

Numbers 1 and 3 were found to be suit-able for making all-position welds inmild steel, with the exception of Elec-trode No. 1 in the overhead position at7 FSW. Both electrodes can be used bya welder/diver with average weldingability; weldability and ease of slagremoval make the electrodes usable withminimal training. Overhead welding ismore difficult than the other positionsdue to decreased visibility of thewelding arc; this is a result of thebubbles being hindered, by the plate,in their movement toward the water sur-face. This results in capping beadswhich are a little more irregular thanthose of other welding positions (seeFigures 24, 28 and 29). Figure 28shows 50 percent of the length of thecap removed by grinding; this was doneto determine whether or not the irregu-lar ("ropy”) bead profile would inter-fere with radiographic film interpreta-tion. It was found that the cap didnot interfere with film interpretation.The undercut shown in Figure 28 is lessthan 1/16 inch in depth.

FIGURE 27. Electrode No. 3Horizontal Qualification33 FSW


Weld quality for both ElectrodeNumber 1 and 3 is considered good andrepresents state-of-the-art technology.The weld quality for both electrodescan be further described as follows,where the visability is good and prop-erly trained welder/divers are used forthe welding:


2.5.2.3 Qualification testingsummary and conclusions. Both Electrode

a. Visual weld appearance shouldconsistently meet the Class 2requirements of NAVSHIPS 0900-LP-003-8000 and the Type B weldrequirements of AWS D3.6.Figures 30 and 31 show close-upviews of Electrode Number 3

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welds made in the vertical posi-tion at 33 FSW.

b. Magnetic particle and liquidpenetrant inspections shouldconsistently meet the Class 1requirements of NAVSHIPS 0900-LP-003-8000.

c. Radiographic inspection shouldconsistently meet the Type Bweld requirements of AWS D3.6.Where porosity less than 1/16inch is ignored, both electrodesare capable of meeting Class 1requirements of NAVSHIPS 0900-LP-9000 in certain instances,and they should meet the Class 3requirements in most cases.Based on mechanical test re-sults, the varying degrees ofporosity (from none, to that al-lowed by AWS D3.6 Type B) showedno effect on either strength ortoughness. A comparison of po-rosity levels between ElectrodeNumber 1 and 3 for identical 33FSW vertical welds, as shown byradiographic film comparison,can be seen in Figures 32 and33; Electrode No. 3 is shown toproduce significantly less po-rosity.

L


The strength, in terms of yield andtensile, of both Electrode Numbers 1and 3 is satisfactory. In comparingbase metal properties of 2.2 with weldmetal properties of Table II, and assummarized in Table III, the followingcan be concluded:

a. Based on average values, theweld metal ultimate strength

b.

exceeds that of the A36 steelby approximately 13 percent;the weld metal yield strengthexceeds that of the A36 steelby approximately 45 percent.

Based on average values, theweld metal ultimate strengthis less than that of the DH 36steel by approximately onepercent. However, the weldmetal yield strength exceedsthat of the DH 36 steel by ap-proximately 22 percent.

FIGURE 31. In-Air Butt Weld(E7018, Single Pass Cap)Intersecting a Wet ButtWeld (Electrode No. 3)Vertical, 33 FSW

FIGURE 32. Electrode No.Radiograph ofVertical Butt

133 FSWWeld

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Weld ductility for both ElectrodeNumbers 1 and 3 is obviously less thanthat of the base metals. It can beseen from Table III that the weld metalelongation is less than one-third thatof the base metals and well below the17 percent minimum required for airwelds. However, successful bend test-ing using 6T (4½ inch diameter) and 4T(3 inch diameter) radius plungersshowed reasonable ductility (air weldsare usually bent using a 1½ inch diame-ter plunger). Since the tensile andyield strengths of the weld metal wereconsiderably higher than that of theA36 steel base metal, the base metalsustained more of the bend elongationthan did the weld; however, since theradius of the bend specimens was fairlyconstant around the circumference ofthe bend (no flat spots in the higherstrength weld area), the weld metalapparently had reasonable elongationand thus ductility. It should also bekept in mind that 30 of 32 face bendspecimens passed the 6T radius bendduring the screening tests, and thatthe base metal was DH 36 steel. Inaddition, 14 of 32 specimens passed the4T tests; those that failed did so inthe heat-affected-zone, as opposed tothe weld metal.

FIGURE 33. Electrode No. 3Radiograph of 33 FSWVertical Butt Weld

The weld metal toughness of Elec-trode Number 1 and 3, as shown by theCharpy impact test, is less than 1/2that of the A36 base metal (see Table111). Howeverr the Charpy breaks ex-hibited a ductile fracture mode (80 to100 percent shear). The work of Ref.8, which will be further discussed inSection 3, showed that wet welds, dis-playing similar results, were at or

near upper shelf at 28 F. Porosityshown in some heat-affected-zone speci-men fracture surfaces, along with erra-tic heat-affected-zone energy values,indicate that the heat-affected-zoneCharpys were not always failing in onlythe heat-affected-zone. The failureswere sometimes veering off toward theweld metal. Heat-affected-zone Charpyimpact average values ranged from 28 to61 foot-pounds.

With respect to macroscopic exami-nation, all the wet welds met the TypeA (dry weld) requirements of AWS D3.6-- except that some specimens had minorroot cracking associated with slag in-clusions or gaps between the plate andbacking bar; AWS D3.6 allows no crack-ing in the MACRO specimens. Most ofthe MACRO specimen root cracking wasnot in excess of 1/32 inch. However,some of the specimens had slag inclu-sions which exceeded 1/32 inch, whichis rejectable to the requirements ofMIL-STD-248C. Representative MACROSare shown in Figures 34 through 40.MIL-STD-248C recognizes that backingbar butt welds have an occasional ten-dency for minor cracking in the root,and will accept these indications ifnot longer than 1/32 inch. This crack-ing tendency was demonstrated in thewet welds, but only associated withminor root slag or, on one occasion, agap between the plate surface and thebacking bar.

FIGURE 34. Electrode No. 1Overhead Qualification33 FSW (3X)

There was no case where the weldmetal hardness exceeded the 325 H 10maximum allowed by AWS D3.6 for Type Awelds. In fact, the weld metal hard-ness never reached 250 HVIO, and the

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majority of the readings were below 200H 10. The only areas exceeding 325EV1O were in the base metal heat-affected-zone just beneath the weldcap. In other work, excessive HAZhardness, just under a wet weld cap,have been reduced to acceptable valuesby using the “temper bead technique”.However, this requires a well trainedwelder/diver and good in-water visi-bility.

FIGURE 37. Electrode No. 3Vertical Qualification33 FSW (3X)


FIGURE 38. Electrode No. 3Overhead Qualification33 FSW (3X)

3.0 DISCUSSION


Two commercially available mildsteel wet welding electrodes have beenqualified to the requirements of AWSD3.6 for wet welding ordinary strengthstructural carbon steel; as allowed byAWS D3.6, this qualification extends toa water depth of 66 feet. Based on therequirements of AWS D3.6, this qualifi-cation is limited to steels with amaximum carbon equivalent of 0.350 anda maximum carbon content of 0.17 per-cent by weight. Additional testingwould be required to qualify the elec-trodes to weld steels with a higher

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carbon content and/or carbon equiva-lent. (A very promising stainlesssteel electrode, for use in welding thehigher carbon equivalent steels, under-went initial screening tests; however,the screening tests could not be com-pleted, because most of the electrodeswere damaged in shipment. Refer toFigures 41 and 42.)

FIGURE 39. Electrode No. 3Overheat Qualification7 FSW (3X)


The qualification testing hasestablished that the mild steel elec-trodes meet a weld quality standardsomewhere between that considered ac-ceptable for wet welds by the AmericanWelding Society, and that considered

FIGURE 41. Experimental StainlessSteel ElectrodeVertical Fillet, 33 FSW

acceptable for dry welds by the U. S.Navy. The primary weld discontinuitywas porosity -- the degree of which hadno observable impact on any of the me-chanical test results. Neither did theminor cracking, associated with rootdiscontinuities, have any impact on themechanical test results. Of the ini-tial 36 side bend specimens, two faileddue to slag/incomplete root penetra-tion; two additional bend specimens,for each failed specimen, passed thebend test for a total of 40 bends.

Bend tests exceeded AWS D3.6 re-quirements for Type B welds, and ten-sile and yield strengths far exceededminimum base metal requirements and therequirements of applicable filler metalspecifications. Weldment toughness andductility are reduced compared to airwelds, but may be considered adequatefor certain applications. Weldmenthardness exceeded AWS D3.6 requirementsfor Type A welds only in the heat-affected-zone just under the weld cap.

Ref. 8, which is an underwaterwelding study performed by the South-west Research Institute for the ShipStructures Committee through the U. S.Coast Guard, makes the following obser-vation in the opening statement of the“ABSTRACT”: “Data reported herein indi-cate that the wet ......welding (SMAW)process can produce welds suitable forstructural applications provided cer-tain limitations of the welds are con-sidered in design.m The SWRI Reportincludes the same mechanical testing ascovered in this report, and in addi-tion, fracture toughness (Jic) testing.Howeverr the SKRI work covered weldsmade only in the flat position, and thewelding took place in fresh water. All

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test results in this report pretty muchparalleled these corresponding tests ofthe SWRI Report. The mechanical prop-erties of electrode Numbers 1 and 3(E7014 “type” electrodes) appear to beequivalent to those of the E6013 “type”electrodes tested in the SWRI work. Itwould be considered worthwhile to makea detailed comparison between the re-sults of this study and the results ofthe SWRI work. The applicability ofthe fracture toughness calculations andweld design recommendations, estab-lished in the SWRI work, could then beassessed for the two wet welding elec-trodes of this study.

Another previous study, Ref. 9,addresses crack growth rate of wetwelds made with E6013 electrodes. Thewelds were made in fresh water at adepth of approximately 33 feet. Twomeaningful conclusions of the Ref. 8study are as follows:

a. Crack growth rates increasedwith porosity level.

b. At stress intensity factors of

below, depending on porositylevel, crack growth rates forthe wet welds were less thanfor surface or dry habitatwelds.

FIGURE 42. Experimental StainlessSteel ElectrodeOverhead Bead-on-Plate33 FSW

In regard to depth, the followingwas found:

a. There was no significant dif-ference in mechanical proper-ties at 7 FSW, as compared to33 FSW, except a slight

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b.

c.

increase in ultimate and yieldstrengths.

Weld metal carbon and manganesedecreased somewhat at the deep-er depth, which may account forthe lower strength levels. Weldmetal oxygen levels at 7 FSWwere only on the average about1.4 percent of that at 33 FSW.

Overhead welding became moredifficult at 7 FSW, such thatElectrode Number 1 could not bequalified.

The results achieved in this proj-ect have shown that wet welding canhave a degree of integrity such thatits use may be justified for limitedapplications in Naval surface ship re-pair. Such applications would include:

- Permanent nonstructural repairin low carbon equivalentsteels.

- Temporary structural repairs,performed on an emergencybasis, where replacement orrewelding of the repaired areamight be deferred until thenext scheduled drydocking.

4.0 ACKNOWLEDGEMENTS

The work was sponsored by Code 00Cof the Naval Sea Systems Command underthe technical direction of NAVSEA Code05M2. Administration and technicalsupport were provided by the CASDE Cor-poration and Welding Engineering Ser-vices. The authors wish to expresstheir gratitude to Cal Dive Companiesand S & H Diving for the welder/diverpersonnel used for the duplicate weld-ing. Special appreciation is expressedto Mr. C. E. “Whitey” Grubbs of GlobalDivers and Contractors; Mr. Grubbs, whois presently the chairman of the Ameri-can Welding Society sub-committee forunderwater welding, provided valuabletechnical input during the life of theproject.

5.0

(1)

(2)

(3)

(4)

(5)

REFERENCES

ANSI/AWS B4.O-85 Standard Methodsfor Mechanical Testing of Welds.

ANSI/AWS D3.6-83 Specificationfor Underwater Welding.

MIL-STD-248C Welding and BrazingProcedure and Performance Qualifi-cation.

MIL-STD-271E (SHIPS) Nondestruc-tive Testing Requirements forMetals.

MIL-S-22698B (SH) Steel Plate;Carbon, Structural for Ships.

(6) NAVSHIPS 0900-LP-O03-8000 SurfaceInspection Acceptance Standards forMetals.

(7) NAVSHIPS 0900-LP-O03-9000 Radio-graphic Acceptance Standards forProduction and Repair Welds.

(8) Norris, E. B., Dexter, R. J.,Schick, W. R., and Watson, P. D.,“Underwater Wet And Wet-BackedWelds: Toughness, Mechanical Prop-erties and Design Guidelines”,Southwest Research Institute(Draft) Report 7168, 31 March 1986.

(9) Matlock, D. K., Edwards, G. R., 01-son, D. L., and Iberra, S., “AnEvaluation of the Fatigue Behaviorin Surface, Habitat and UnderwaterWet Welds”, Submitted to the SecondInternational Conference on Off-shore Welded Structures, London,England, 16-18 November 1982.

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Additional copies of this report can be obtained from theNational Shipbuilding Research and Documentation Center:

http://www.nsnet.com/docctr/

Documentation CenterThe University of MichiganTransportation Research InstituteMarine Systems Division2901 Baxter RoadAnn Arbor, MI 48109-2150

Phone: 734-763-2465Fax: 734-763-4862E-mail: [email protected]

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TABLE II. TENSILE AND IMPACT QUALIFICATION TEST RESULTS

ELECTRODE AND TENSILE STRENGTH, PSI YIELD STRENGTH, PSI ELONGATION, % IMPACT ENERGY AT28°F, FT.LBS.

WATER DEPTH Minimum Maximum Minimum Maximum MinimumMaximum *Minimum *Maximum

ElectrodeNo. 1 73,40033 FSW




74,500 65,300 68,100 6.6 9.3 29.8 31.8

75,900 65,800 68,350 8.0 8.8 33.5 33.5

83,050 70,900 76,550 6.0 8.3 25.1 32.0

84,050 74,500 82,400 4.8** 8.8 28.2 24.5

*

**

Basedon averagevaluesforeachweldmenttested.

Questionablevalue.

TABLE III.COMPARATIVE WELD METAL/BASE METAL PROPERTIES

Average AverageBaseMetal BaseMetalSpec.

Properties WeldMetal A36 DH 36 A36 DH 36

TensileStrength** 77.6 68.8 78.7 50-80 71-90KSI

YieldStrength** 71.5 49.4 58.5 36 Min. 51 Min.KSI

Elongation,%** 7.6 27.7 23.7 23 Min. 22 Min.

ImpactEnergyat 29.8 75.5 No Tests Not N/A*28°F, Ft.Lbs. Run Req’d.

* Differenttemperaturerequirements.

**From all-weld-metaltesting.

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Documents

THE NATIONAL SHIPBUILDING RESEARCH PROGRAM · accomplished in accordance with MIL-STD-271 (Ref. 4).Destructive examination specimens were prepared and tested in accordance with AWS