Effects of Electrode Composition, Flux Basicity, and Slag Depth on Grain-Boundary Cracking in Electroslag Weld Metals

Transcription

1 Effets of omposition, Basiity, and Slag Depth on GrainBoundary raking in Eletroslag Weld Metals An aidi flux, a high slag depth, and highsilion eletrodes are found to help eliminate grainboundary raking BY P. J. KOKOL ABSTRAT. Previous researh investigations showed that grainboundary separations, whih are small raklike imperfetions usually less than Vt in. (6. mm) long in eletroslag weld metals, are due to the presene of hydrogen, whih an result from moist flux or from moisture in the atmosphere above the weld pool. These studies indiated that the amount of raking was redued by lowering moisture ontent, using a neutral rather than a basi flux, lowering external restraint, dereasing the weldooling rate, or using a postweld heat treatment. To determine the importane of other fators involved, suh as grade of steel welded, flux basiity, slag depth, and eletrode omposition, eletroslag welds were made under onditions of relatively high external restraint and high moisture levels above the slag in in. ( mm) thik plates of and 7 Grade A steel. The onsumable guide eletroslag welding proess was used, and a small steel gasarrier tube was positioned beside the guide tube to provide an atmosphere of air having or % water vapor above the molten slag. Welds were made with Amerian Welding Soiety (AWS) (.Mn.Si) or (.Mn.Mo) eletrodes, with five fluxes having basiities from.7 to.. A number of welds were made in whih three different slag depths were Paper to be presented at the 6th AWS Annual Meeting in Philadelphia, Pennsylvania, under sponsorship of the Welding Researh ounil High Strength Steel Subommittee during April, 8. P. j KOKOL is Senior Researh Engineer. Researh Laboratory, U.S. Steel orporation, Monroeville, Pennsylvania. used; Vi, VA, or Vi in. (, 8 and 7 mm). Additional welds were made with EHEW (.Mn), EHKEW (.6Mn.Si), and EHMoEW (.8Mn.7Si.Mo) eletrodes. The results showed little differene in the amount of grainboundary raking in eletroslag welds made in and plates. The amount of raking dereased with dereasing flux basiity (B). Very little raking was observed in welds made with aidi (B ) fluxes. raking was eliminated by inreasing the slag depth to VA in. (7. mm). The highsilion eletrodes, EHKEW and EHMoEW, substantially lowered the amount of raking. The reasons for the benefiial effet of silion in reduing raking are not fully understood. As shown previously, it should be possible to eliminate grainboundary separations by using welding praties that minimize moisture pikup and other soures of hydrogen or by allowing hydrogen to diffuse out of the weld during ooling or during postweld heat treating. The present work indiates that using an aidi flux, maintaining a high slag depth, and using highsilion eletrodes are also benefiial. However, the use of the two highsilion eletrodes investigated (EHKEW and EHMoEW) resulted in exessively high weldmetal tensile strength. Introdution Oasionally, small raklike imperfetions (usually less than VA in., 6 mm, long) have been observed in eletroslag welds made by fabriators under prodution onditions; these imperfetions have aused onern about the use of eletroslag welding (ESW) for ritial appliations, suh as tension members in bridges (Ref. ). These raklike imperfetions are frequently alled grainboundary separations or raks. To help establish the use of this eonomial welding proess in bridges and other ritial appliations, the auses of grainboundary raking need to be identified, and proedures to avoid their ourrene must be established. Previous studies (Ref. ) indiated that grainboundary raking ourred in weld metals made with a variety of eletrodes and steelplate ompositions and were not assoiated with segregation of alloying elements or impurities. Reent studies (Ref. ) have shown that grainboundary raking ould be produed by the addition of moisture to the welding flux or to the atmosphere above the molten flux or slag. The presene of suh raks ould be redued or eliminated by reduing external restraint, by lowering the moisture ontent, or by using a lowtemperature postweld heat treatment. Thus, the raking appeared to be hydrogenindued. Similar studies onduted at Lehigh University (Ref. ) showed that grainboundary raking ould also be produed from hydrogen in the eletrode or in the atmosphere above the molten slag. These studies suggest that it should be possible to eliminate grainboundary raking by using welding praties that minimize moisture pikup or other soures of hydrogen, or by allowing hydrogen to diffuse out of the weld during ooling or during postweld heat treating. However, these praties are not always feasible during the prodution of eletroslag weldments. The present studies were initiated to determine the extent to whih the base metal, flux harateristis, and eletrode hemial omposition affeted the level of raking. Two steel grades ( and ) were inluded in the present study to WELDIG RESEARH SUPPLEMET 6s

2 Table hemial omposition of Plates Used to Fabriate Eletroslag s, % (Ladle Analysis) Steel grade 7 grade A 8a grade A Heat no. 7B 7E 7E6 7B 6E Mn P S Si u..... i r..... Mo..... V _.... Al... Table hemial omposition of s Used to Fabriate Eletroslag s, % MedMnSi Mn MnMo () MnSi MnSiMo Designation' ' EHEW b > EHKEW EHMoEW..... Mn P S..... Si u... d >.. i... r... Mo _.... (a) AWS.78, Speifiation tor onsumables used for Eletroslag Welding of arbon and HighStrength, LowAlloy Steels. b) AWS.8, Speifiation for Bare LowAlloy Steel s and Eluxes for Submerged Ar Welding ^'Manufaturer's analysis. (d) Exlusive of opper oating. determine whether steel omposition and/or strength level affeted the degree of raking. With regard to flux harateristis, prior studies indiated that a basi flux (Ref. ) and low slag depth (Ref. ) ontributed to raking. Thus, the effets of flux basiity and slag depth were investigated. Although grainboundary raking is the result of hydrogen in the weld, the degree of raking may also be affeted by the mirostruture and hardness of the weld metal; this, in turn, is affeted by its hemial omposition. To determine the effet of eletrode omposition on grainboundary raking, the effets of silion in both manganese and manganesemolybdenum eletrodes were studied. As part of a supplementary program to improve the noth toughness of eletroslag weld metals, the harpy Vnoth (V) energy absorption of several weldments, made with various eletrodes and fluxes in the present investigation, was determined. Also, weldingproedure qualifiation tests were onduted by using weldments made with a EHlOMoEW eletrode, whih initially appeared to be promising with respet to both toughness and raking resistane. The results of the various studies are desribed in this paper. Materials The steel plate used for the majority of the weldments in the present study was in. ( mm) thik ASTM plate obtained from three different heats. Seleted weldments were also made with in. thik ASTM 7 Grade A plates from a single heat. s for the weldingproedure qualifiation tests were made from in. thik and 8a Grade A plates. The hemial ompositions of the heats are shown in Table. The majority of weldments were made using an AWS in. (. mm) diameter eletrode, a MnSi eletrode. Other eletrodes investigated inluded EHEW (Mn), EHKEW (MnSi), EHMoEW (MnSiMo), and (Mn Mo) of AWS A.8. The hemial ompositions of the eletrodes are shown in Table. To determine the effet of flux on the ourrene of grainboundary raking, five ommerially available fluxes that ranged in basiity from.7 to. were used. The hemial ompositions of the fluxes are shown in Table. Experimental Work Fixturing All weldments were fabriated with a high level of external restraint that was ahieved by means of 6 8 in. ( 7 mm) restraint bars that were attahed with Vi in. ( mm) throat fillet welds aross the top of eah weldment, as shown in Fig.. A in. long ( mm) starter blok was plaed 7 in. ( mm) below the top of the plates. The length and width of the welded plates Table hemial omposition of es Used to Fabriate Eletroslag s basiity,a) omposition/^ %: Si AIO ao ao > MgO MnO FeO Fe Ti af W ao + MgO + af + Vi (MnO + FeO) A S.O + V (MO + Ti + Zr) b) Assuming the elements are present as oxides exept as noted. t) Assuming all F is present as af and exess a from af is present as ao Bl s I MARH 8

3 Fig. Fixturing for weldment with restraint bars. All dimensions in inhes varied with eah weldment, beause the plates were ut and reused in further studies after eah weld was made. However, for every plate, the width and length were equal to or greater than in. (6 mm) and in. ( mm), respetively. Moisture Addition ontrol of the moisture level of the air above the molten slag during welding was ahieved by blowing air through a VA in. (6. mm) outsidediameter steel /" FIETS TOP + BOTTOM O TWO RESTRAIT BARS OVETIOAL STROGBAKFOR SHOE RETETIO tube that was attahed parallel to the guide tube. During welding, both tubes were melted slightly above the molten slag. A weldment with the ontrolledatmosphere apparatus is shown in Fig.. The partial pressures of water vapor in the air were 6,, and mm merury, whih orrespond to,, and vol% H, respetively, and were obtained by bubbling air through water at, 8, and 6 F (,, and 76 ), respetively. The tehnique is desribed in detail in a previous study (Ref. ). Table onditions Held onstant during Fabriation of Eletroslag s (a) Proess : Shoe : External restraint Postweld treatment Guidetube Slag depth, inh diameter, in. Welding urrent, A Welding voltage, V feed rate, ipm: Energy input, k)/in. Single, fixed onsumableguide tube Waterooled, opper, 8 in. long, gallons per minute flow rate. High one Vi in. O. D., bare V, exept where varied Va 6 ' ' inh =. mm: gallon =.78 liters: ipm =. mm/s: k]/inh =. kl/mm 6 Fig. Setup for eletroslag weldment with high external restraint and moisture addition to the welding atmosphere Welding Exept for plate grade, eletrode, flux, and moisture level, all welding onditions shown in Table were held onstant. The ombinations of welding parameters that were intentionally varied are shown in Table. When Va in. diameter (. mm) eletrodes were used, the welding voltage and eletrodefeed rate were lowered to obtain the approximate fill rate and energy input of welds made with the % in. diameter (. mm) eletrodes. The tops of the shoes were butted against the underside of the restraint bars, and the welding was terminated when the slag reahed the top of the shoes. The shoes were left in plae with the water running for about hours (h) after welding to bring the weldment to room temperature in a relatively short time. The weldments were left with the restraint bars intat for at least 8 h before setioning to allow any delayed raking to our. To determine the reproduibility of the raking data, eight weldments representing low, medium, and high levels of raking were repeated. The results were analyzed statistially to determine what levels of differenes in raking were signifiant. raking Measurement A setion ontaining the weld metal, whih was in. wide (76 mm) by plate thikness by the length of the weld (about in. or mm), was oxygenut parallel to the diretion of welding. Eah setion was mahined to the quarterthikness loation by removing Vi in. ( mm) of metal from both sides on a plane parallel to the plate surfaes and weld faes. The two mahined surfaes were surfaeground, ethed lightly, and examined for grainboundary separations by using dye penetrant. The number of raks observed on both surfaes at the V in. ( mm) depth was ounted and reorded. An additional VA in. (6. mm) of metal was then removed from both sides, and these surfaes were again examined for raking. Indiations that were loated within in. (. mm) of the start or finish of the weld were disregarded. The average WELDIG RESEARH SUPPLEMET 6s

4 number of raks observed at the Vi and / in. ( and 8.8 mm) depths was used for the data analysis and is reported in Table. Additional Studies On seleted weldments, the Vi in. ( mm) thik setion that remained after the dyepenetrant examination was setioned for analysis of the hemial omposition, for metallographi examination, for mirohardness measurements, and for mehanialproperty (impat and tension) determinations. Eight V speimens were mahined from the weldments suh that their orientation was transverse to the welding diretion and the axis of the noth was normal to the plate surfae at the midthikness of the weld on the weld enterline. The eight V speimens were tested at F (8 ). The highest and lowest values were disarded, and the average of the six remaining values was reported. Longitudinal. in. (6. mm) diameter tension speimens were also mahined from several weld setions. The speifi weldments involved are listed in Table 6. WeldingProedure Qualifiation Tests An eletroslag weldment was made in a in. ( mm) thik plate of both and 8a Grade A steels by using EHMoEW eletrode and. The welding onditions were the same as shown in Table exept that restraint bars were not used and moisture was not added to the atmosphere above the slag. After welding, standard weldingproedurequalifiationtest speimens were obtained and tested in aordane with the AWS Strutural Welding ode (Ref. ); these onsisted of transverse tension speimens, sidebendtest speimens, longitudinal. in. (.8 mm) diameter allweldmetal tension speimens, and V impattest speimens. The number and loation of the speimens are shown in Fig.. Table Desript ion of Parameters Used in Fabriating Eletroslag s and umber of raks Deteted Plate grade Type Diameter, in. W Vi in. depth umber of raks % in. depth Avg. omparison of Plate Grade: % hi 7 I'! Effet of flux basiity: hi A Bl Reproduibility: 6 8 / Effet of slag depth: 6 A B 7 ('/ in.) (Vi in.) (W in. ) ( VA in. ) (VA in. ) 6 7 Effet of eletrode : EHEW EHEW EHEW EHEW EHKEW EHKEW EHKEW EHIOMoEW EHMoEW EHMOEW % % fr hi h % hi h h % n in. = ^. mm. 66sl MARH 8

5 Table 6Tests of Eletroslag Weld Metals WELD no. hemial omposition Metallographi examination Mirohardness harpy Vnoth Tension x REDUED SETIO TESIO REDUED SETIO TESIO i Results and Disussion The number of raks observed at distanes of Vi and /A in. ( and mm) from eah surfae of all the weldments investigated are shown in Table. Table 7Reproduibility of Weld raking Data A 7 EHMoEW EHIOMoEW EHKEW EHKEW EHEW EHEW EHEW (Vl in.) (Vl in.) (VA in.) (Vt in.) (a) Average of the raking observed at Vi and /i in. ( and mm) depths. Examination of the data in Table shows that, in general, the level of raking is higher at the VA in. ( mm) distane than at the Vi in. ( mm) distane. The greater degree of raking was probably aused by the expeted higher residual Average no. of raks' ' 8 6 Fig. Layout of AWS welding proedurequalifiation test speimens tensile stresses near the enter of the weld and higher hydrogen onentrations beause of greater diffusion distane to the weld surfae. The effets of individual variables are disussed in the subsequent setions. Reproduibilityofraking Data A omparison of the eight sets of weldments that exhibited low, medium, and high levels of raking that were repeated by using the same parameters is shown in Table 7. In most ases, the degree of raking was similar between similar welds. However, in two of the sets, the raking differed by an order of magnitude. A omparison of three of the sets ( and 66; and ; and ) showed little differene in hemial omposition between similar welds Table 8. A statistial analysis of the data by analysis of variane and/or regression tehniques indiated that, within % onfidene limits, there is a real differene between two individual Table 8hemial omposition of Eletroslag.Veld Metals, % Weld Mn P s Si u i r Mo V Ti Al O WELDIG RESEARH SUPPLEMET I s

6 Table Effet of Plate Gradt on Degree of GrainBoundary raking 6 78, K IOOO IOO IO Plate grade st//./iv/,///./a / ' nva/ AV'VAVZAAAJAU / A/ J^~^^^^^ 7/Ay YA o PLATE, YA EMIKEW ELETRODE Vi K> PLATE, ELETF.DE I 6 FLU BASIITY Fig. Effet of flux basiity on number of grainboundary separations observed in eletroslag weld metal ounts if the differene between the logarithms of the number of raks ounted plus one [logio (n + ) ] exeeds.8. Thus, in subsequent disussion of the fators that affet raking, this variability in amount of raking must be onsidered. Suh fators as guidetube position, slag depth, wellpool geometry, shoe fitup, residualstress level, or gasflow rate may have ontributed to this variability. Effet of Plate Grade A omparison of four sets of welds in whih the only variable was plate grade ( vs. 7 Grade A) is shown in Table. Statistial analysis of these data indiates that there is no signifiant differene in raking between welds made in and steel. Effet of Basiity Average no. of raks 8, 8 7 The effet of inreasing flux basiity from.7 to. on inreasing the amount of raking is shown in Table, and the data are plotted in Fig.. Similar raking behavior was observed in both steels. The basi fluxes (B >.) resulted in the most raking (7 to raks); the neutral flux, flux (B =.), resulted in moderate raking ( to raks); and the aidi fluxeses and A (B ) resulted in the fewest raks (i.e., and ). The reason for the detrimental effet of basi fluxes on raking may possibly be related to the inreased dissolution of water vapor into basi molten slags (Ref. 6), with subsequent transfer of hydrogen into molten weld metal. Another possible explanation is that lowbasiity (aidi) fluxes generally result in high oxygen levels in the weld metal. High oxygen ontents limit the amount of hydrogen that will dissolve in the metal (Ref. 7). For example, weld 7, made with the aidi flux (B =.7), had.8% oxygen ompared with.7% oxygen in weld made with the basi flux (B =.). However, for the other welds,in this study, no orrelation between raking and oxygen ontent was observed. Effet of Slag Depth The depth of molten slag is diffiult to measure and ontrol during onsumableguide welding. When the minimum amount of flux is added to prevent audible aring during welding, the depth of solidified slag at the end of the weld averages about VA in. ( mm). By adding less flux and more flux than was neessary, slag depths of Vi and VA in. ( and 7 mm), respetively, were obtained. The effet of slag depth on degree of grainboundary raking is shown in Table. Again, onsiderable satter in a number of raks was observed. However, there was a statistially signifiant effet of inreased slag depth on reduing the amount of raking. The welds made with a VA in. (7 mm) slag depth exhibited little or no raking in the presene of % moisture in the atmosphere. This is in agreement with other work (Ref. ) in whih raking was eliminated when the slag depth was inreased to. in. ( mm). The reason for the lower amount of raking with inreased slag depth is not known. It ould possibly be related to elimination of aring, lowering of slagbath temperature, hanges in irulation patterns of the molten slag, or lowering of hydrogen onentration in the slag beause of the greater slag volume. As shown in Table 8, the only signifiant effet of inreasing slag depth from Vi in. or mm (weld 6) to VA in. or 7 mm (weld ) on weldmetal hemial omposition was to lower the oxygen ontent from. to.%. However, as noted in the previous disussion of the effets of weldmetal oxygen, this would be expeted to inrease the amount of hydrogenindued raking. Effet of omposition As shown in Table, the use of eletrodes ontaining.6 to.8% manganese and. and.7% silion (EHKEW and EHMoEW, respetively) substantially lowered the amount of grainboundary raking ompared with the use of EHEW and, whih are similar in omposition exept for silion. raking was nearly eliminated when the highsilion eletrodes were used in the presene of % moisture and was signifiantly lowered in the presene of % moisture. Table Effet of Slag Depth on Degree of GrainBoundary raking' ' Table Effet of Basiity on Degree of GrainBoundary raking (a) 7 6 7, 86 Plate grade a) AII welds were made \ vilh ",. moisture n in the atmostphere. A Bl basiity Average no. of raks, 7 6 A B 7 Slag depth in.) Vi Vi VA VA V/A VA VA Average number of raks 7 (a) AII weids were made with EM KEW eletrode, flux, and ".. moisture in the atmosphere. (b) in. =. mm 68s MARH 8

7 .;fr. yy ::' /, '.,. x,.'a ^.( ) ; V^.... ' Hg. Effet of eletrode omposition on mirostruture of eletroslag weld metals: A weld ; EH EW (.Mn); Bweld 66; EHVIKEW (.6Mn.Sl); weld ; (.Mn.Mo); Dweld 7; EHIOMoEW (l8mn.7si.mo). italpiral eth. IOO (redued 6% on reprodution) The effet of silion ontent on weld mirostruture is shown in Fig.. The morphology of the grainboundary ferrite was hanged from predominantly polygonal to predominantly sideplates, and the matrix was hanged from a oarse to a fine Widmanstatten struture by the use of EHKEW (.6Mn.Si) rather than EH EW (.Mn) eletrodes Fig. A and B. The weldmetal silion ontent was inreased from.8 to. to. to.% Table 8 (welds and vs. and 66, respetively). For the eletrode, (Mn.Mo), the amount of grainboundary ferrite was lower than that for EHEW or EHK EW, and the matrix was primarily bainite, Fig. EHIOMoEW eletrode (.8Mn.7Si.Mo) resulted in very little grainboundary ferrite and a matrix that appeared to be aiular ferrite Fig. D. In these welds the silion ontent was raised from.8 to.8% (welds and 7). Although it appears from Fig. that lowering the amount of grainboundary ferrite was benefiial, grainboundary raking has been observed in weld metals that ontained no grainboundary ferrite (Ref. ). Thus, the reason for the benefiial effet of silion on reduing grainboundary raking annot be explained on a mirostrutural basis. It was also postulated that the raking was onfined to the grainboundary ferrite beause it was softer than the matrix, and silion would redue raking by solidsolution strengthening the ferrite. Thus, mirohardness readings were obtained on the four weld metals shown in Fig.. The results in Table, however, show that silion inreased the hardness of the matrix and slightly lowered the hardness of the ferrite, thus inreasing the differene in hardness. In the absene of a satisfatory mirostrutural explanation for the effet of silion on raking, it is postulated that Table Effet of omposition on Degree of GrainBoundary raking EH EW EHKEW EHIOMoEW ominal omposition.mn.6mn.si.mn.mo.8mn.7si.mo (a) umbers in parentheses are weld s. (,, ) (, 66) () (7, ) Table Mirohardness of Eletroslag Weld Metals 66 7 EH EW (.Mn) EHKEW (.6Mn.Si) (.Mn.Mo) EHMoEW (.8Mn.7Si.Mo) Matrix 6 68 (a) Average of five Vikers diamondpyramidhardness impressions with a gram load. Average number of raks' ' % moisture % moisture,,,, Mirohardness, HV. (a > rainrboundary ferrite (8) (8) () (8) 7 Differene 7 8 silion may affet the solubility or diffusivity of hydrogen in the weld metal. Silion does lower the solubility of hydrogen in liquid iron (Ref. 8); however, the effet is believed to be relatively small for the range of silion ontents in this investigation (Ref. ). Another possible mehanism is the effet of silion on inlusion. As silion ontent inreases, the predominant inlusion would be expeted to hange from MnO to MnSi> to Si>. It is suggested (Ref. ) that inlusion s an differ in their ability to absorb hydrogen and an either enhane or retard hydrogen raking. However, little work has been done in this area. oth Toughness of Weld Metal The results of the V impat tests obtained from material at the midthikness of the weld metal of seleted weldments are shown in Table. These results indiate that a weld metal made with EHMoEW eletrode and flux exhibited exellent noth toughness: ftlb (6 J) at F (7.8 ). Thus, this eletrode initially appeared to be attrative in terms of both resistane to grainboundary raking and high noth toughness. WeldingProedure Qualifiation Tests To determine whether eletroslag welds made with highsilion eletrodes would have adequate mehanial properties for strutural appliations, standard AWS WeldingProedure Qualifiation tests of eletroslag weldments of and 8a Grade A steel were onduted by using EHMoEW eletrode. The results are shown in Table. Although the weld region exhibited adequate soundness as evidened by the transversetensionand sidebendtest results, the tensile strength of the weld metals exeeded that speified in the AWS A.78 speifiation for ESW onsumables (Ref. ). In addition, the tensile elongation was lower than the speified minimum, and the V energyabsorption values at F of 7 and ftlb (7 and J) were muh WELDIG RESEARH SUPPLEMET 6s

8 lower than the ftlb observed previously. Thus, EHMoEW eletrode with flux does not appear to be suitable for ESW from a mehanialproperty standpoint. The high strength and low dutility of eletroslag weld metal made with EHMoEW eletrode may be due to the relatively high alloy ontent of the eletrode (.8Mn.7Si.Mo). To determine whether the molybdenumfree highsilion eletrode (EHKEW) investigated would result in lower strength weld metal, the tensile properties that were obtained from the weld metal of weldments 8 and 66 (made with EHK EW eletrode) were ompared with that for weldment 7 made with EHIOMo EW eletrode. The results in Table 6 show that EHKEW eletrode also resulted in weldmetal tensile strengths in exess of the 8 ksi ( MPa) maximum for steel speified in AWS A.78. Thus, neither of the two highsilion eletrodes would meet lassifiation requirements of AWS A.78 when used with neutral flux, and these eletrodeflux ombinations would not be suitable for use in eletroslag weldments that must meet AWS D. speifiation requirements. General Disussion It was previously shown (Ref. ) that grainboundary raking was aused by hydrogen in the weld metal; thus it should be possible to minimize or eliminate raking by using welding praties that minimize moisture pikup or other soures of hydrogen or by allowing hydrogen to diffuse out of the weld by slow ooling or by postweld heat treatment. The present work indiates that, if these measures are impratial, additional proedures of using an aidi flux or maintaining a high slag depth would also be benefiial. However, it is not lear whether the benefiial effets are beause of a lower hydrogen level in the weld metal. Use of a highsilion eletrode is also benefiial in reduing raking but may not be benefiial in terms of mehanial properties. Table oth Toughness of Eletroslag Weld Metals, 7 86 la> ftlb =.6 I EH EW EHKEW EHIOMoEW B V energy absorbed at F (8 ), ftlb' ', 6 Table Results of Eletroslag Welding ProedureQualifiation Tests with the Use of EHIOMoEW ' ' Qualifiation test: Transverse tensile strength, ksi Frature loation Sidebendtest results Allweldmetal tensile properties: Yield strength (.% offset), ksi Tensile strength, ksi Elongation in in., % Redution of area, % V energy absorption, ftlb: Weld metal (=F), (8 = ) AWS A.78 requirement^' Yield strength, ksi Tensile strength, ksi Elongation, % steel 8. Base metal Passed min 6/8 min " ksi = 6.8 MPa; ftlb =.6 I ^"Speifiation for onsumables Used for Eletroslag Welding of arbon and HighStrength, LowAlloy Steels.' onlusion To further define the fators that affet the inidene of grainboundary raking in eletroslag weld metal, additional studies were onduted to determine the effets of steel grade, flux basiity, slag depth, and eletrode omposition. The results are summarized as follows:. Eletroslag welds made in and 7 Grade A plates showed no statistially signifiant differene in amount of grainboundary raking.. Grainboundary raking inreased with inreasing flux basiity. Very little raking was found in welds made with 8a grade A steel 8. Base metal Passed min 7/ min aidi (B ) fluxes.. Grainboundary raking was nearly eliminated in highly restrained welds made in the presene of % perent moisture above the slag by inreasing the slag depth to VA in. (7 mm).. EHKEW and EHMoEW eletrodes, whih ontain. and.7% silion, respetively, substantially lowered the amount of grainboundary raking in highly restrained eletroslag weldments in the presene of up to % moisture above the slag.. Eletroslag weld metals deposited with the EHKEW and EHMoEW eletrodes and a neutral flux exhibited Table 6Tensile Properties of Weld Metals Deposited with HighSilion s in Steel Yield strength (. o offset), ksi Allweldmetal tensile properties',*> Tensile strength, ksi Elongation in in. % Redution of area, % EHIOMoEW EHKEW EHKEW (a> Longitudinal. in {6. mm) diameter speimens at midthikness loation. Also, ksi = 6.8 MPa; in. =. r 7s MARH 8

9 tensile strengths that exeeded the maximums imposed in the Amerian Welding Soiety fillermetal speifiation for eletroslagwelding onsumables. Referenes. Benter, W. P., r., Konkol, P. )., Kapadia, B. M Shoemaker, A. K, and Sovak,. F. 77 (April ). Aeptane riteria for eletroslag weldments in bridges, phase I final report. HRP projet.. Konkol, P..', and Domis, W. F. 7. auses of grainboundary separations in eletroslag weld metals. Welding journal (6): 6s to s.. Lehigh University. 8 ()une ). Final report, ferrite vein raking in eletroslag welds. AISI projet.. Kunihiro, T and akajima, H. 7. Miroraking in onsumable nozzle eletroslag weld metal. Proeedings of lapanu.s. seminar in signifiane of detets in welded struture.. Amerian Welding Soiety. 8. Strutural welding (AWS DI 8). Miami, Florida. 6. akano, S., Tamaki. K., and Tsuboi, ). Hydrogen and raking in ESW weld metals. International Institute of Welding Doument no. J Fedorosi, V.. and Shubin, V. I. 76 (ov. ). Effets of flux on the resistane of welded joints in IOKh6B steel to the formation of old raks during welding. Automati Welding :7. 8. Turkdogan, E. T. 8. Physial hemistry of high temperature tehnology. Aademi Press.. Turkdogan, E. T. 8. Private ommuniation. otie The material in this paper is intended for general information only. Any use of this material in relation to any speifi appliation should be based on independent examination and verifiation of its unrestrited availability for suh use, and a determination of suitability for the appliation by professionally qualified personnel. o liense under any United States Steel orporation patents or other proprietary interest is implied by the publiation of this paper. Those making use of or relying upon the material assume all risks and liability arising from suh use or reliane. r Z E Q. > LU O I. tr.. t L O WR Bulletin 8 Otober, 8 Hydrodynami Response of Fluid oupled ylinders, Simplified Damping and Inertia oeffiients by S. J. Brown This study presents the development of the onept of inertia and damping oeffiients in an historial ontext with experimental, lassial and numerial investigations into the dynamis of fluid oupled ylinders. It is shown that oeffiients may be used to aount for oaxial ylinder end onditions, eentriity, skewness, lusters, shell modes and axial modes. Publiation of this report was sponsored by the Subommittee on Dynami Analysis of Pressure omponents of the Pressure Vessel Researh ommittee of the Welding Researh ounil. The prie of WR Bulletin 8 is $. per opy, plus $. for postage and handling (foreign + $.). Orders should be sent with payment to the Welding Researh ounil, E. 7th St., Room, ew York, Y 7. WR Bulletin 8 ovember, 8 ElastiPlasti Bukling of Axially ompressed Ring Stiffened ylinderstest vs. Theory by D. Bushnell onern for the safety of nulear plants and offshore strutures has stimulated efforts to determine bukling harateristis of stiffened ylindrial steel shells. In this paper, BOSOR omputer programs were used to predit bukling loads of forty axially ompressed mild steel ylindrial shells previously tested at hiago Bridge & Iron o. Publiation of this report was sponsored by the Subommittee on Shells of the Pressure Vessel Researh ommittee of the Welding Researh ounil. The prie of WR Bulletin 8 is $.7 per opy plus $. for postage and handling (foreign + $.). Orders should be sent with payment to the Welding Researh ounil, E. 7th St., Room, ew York, Y 7. I a LU tr. a. _ > I r tr. i z a tr. L > LU a i o LU o WELDIG RESEARH SUPPLEMET I 7s