FCAW Welder Guide Book 1

8/10/2019 FCAW Welder Guide Book 1

1/17

FILARC welder guide

book No.1

PZ6125 basic flux-cored wire

and related types for high ten-

sile and creep resistant steels

Index page 1

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Welder Guide Book No. 1

FILARC PZ6125 basic flux-cored wire

and related types for high tensile

and creep resistant steels

A new generation of basic cored wires with excellentwelding characteristics for positional workon high quality fabrication
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2/17

FILARC welder guide

book No.1

PZ6125 basic flux-cored wire

and related types for high ten-


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Due to its policy of continual improvementsin its welding consumables, FILARC reservesthe right to change data in this guide without notice.

FILARC Welder Guide Books provide practical information onthe use of specific FILARC flux and metal-cored wires. Thecontents will assist welders to apply correct welding parame-ters and use the FILARC cored wire effectively, to achieve op-timum productivity and avoid faults.The information provided will be helpful to welders both quali-fied or still to qualify for cored wire welding. There is also help-ful information for welding engineers establishing appropriatewelding procedures, also training instructors and welding fore-men.Overall the guide will enhance results from the FILARC flux ormetal-cored wire(s) described.

FILARC PZ6125 is decribed in this guide, together with re-lated types, listed below, having identical welding perfor-mance. All types come in diameter size 1.0, 1.2 and 1.6mmand are developed for use in Ar/CO2 mixed gas.

Low alloyed types AWS A5.29 EN 758FILARC PZ6125 E71T5-G T 42 6 1Ni B M 1 H5

High tensile typesFILARC PZ6145 E81T5-G T 50 5 Mn1Ni B M 1 H5FILARC PZ6146 E91T5-K2 FILARC PZ6147 E101T5-K3 FILARC PZ6148 E111T5-K4 FILARC PZ6149 E121T5-G

Creep resistant AWS A5. ../types DIN 8575FILARC PZ6201 DIN: SGCrMo1 FILARC PZ6202 29:E71T5-A1 FILARC PZ6203 DIN: SGCrMo2 FILARC PZ6204 22:E502T-1 FILARC PZ6205 29:E81T5-B2

Introduction

FILARC PZ 6125 represents a new generation of basic flux-cored wires, with much improved weldability. PZ 6125 yieldsexcellent mechanical properties, including satisfactory CTODvalues, both as-welded and stress relieved, with hydrogencontent dependably below 3ml/100g.PZ 6125 and related types provide good all-position weldabili-ty, with useful tolerance in welding parameter setting; they are

far easier to use than conventional basic cored wires.However, due to the new flux formulation, weldability has dis-tinctive, but not difficult, characteristics.This Guide Book provides all the information you need to en-sure fully satisfactory use of these new basic cored wires.

Index

Correct use of equipment...........................................Page 2

Torch, liners and cable assembly.... .......................................2

Wire drive unit.........................................................................2

Gas regulation ............................................................... .........2

Gas cup and contact tip combination................... .................4

Correct stickout length ...........................................................4

Gas cup sizes ...................................................... ...................4

Power source facilities............................................................6

Welding parameter setting......................................................8

Choice of wire size ........................................................ .......10

Recommended average parameter setting........... ...............12

ASME and EN welding positions.......................... ................15

Welding advice .............................................................. .......16

Torch positions for positional welding ..................................18

Weaving technique ......................................................... ......22

Grinding .............................................................. ..................24

Trouble shooting ............................................................. ......26

Causes of weld defects............................. ...........................27

1
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3/17

FILARC welder guidebook No.1

PZ6125 basic flux-cored wireand related types for high ten-


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Correct use of equipment

FILARC P Z6125 and other cored w ires w ill always pe rformwell when welding sets a re used co rrectly and maintained a c-cording to the makers instructions.Following a re some simple guidelines for preventive inspec tionand maintenance. When carried out regularly, the most com-mon ca uses o f malfunctioning a re avoided.

Torch, liners and cable assembly

Ensure that the contact tip has the right size and is mountedtight. Ideally, contact tips are checked for wear upon wirespool change and replaced when necessa ry.Check gas cups for spatter built-up and clean if necessary. Im-peded g as flow from clogged cups may c ause porosity.Blowing-out the liner into the d irection of wire delivery s houldbe a regularly recurring routine. Check liners for damage atleast weekly, and replace when necessary. Spiral steel linersare recommended.Check ga s a nd w ater connections for leaks. When fitted, en-sure water cooler is filled and pump operates satisfactorily.

Wire drive unitWire guide tubes must be as close to the rollers as possible toprevent kinking of a cored wire. Proper alignment is essentialto avoid unnecessary friction. A substantial amount of finemetallic swarf underneath the drive wheels indicates misalign-ment (or excess ively wo rn drive wheels).Use d rive whee ls with a V-groove an d, by preference, flat pres-sure wheels. Check that the groove of the drive wheel is cor-rectly selected for the wire diameter, and that the pressurewhee l is co rrectly tensioned . Too muc h pressure ma y flattenthe cored wire, giving increased wear of liner and contact tip.Insufficient press ure may result in s lip, ca using erratic wire feedand b urn-back. Limit the use of knurled wheels to situationswhere friction in the liner causes wheels w ith a V-groove to slip.This is only likely to happe n w ith long, extremely curved c ableas semb lies, and /or with units with one s et of rolls. Knurledwhee ls cause increased wea r of liner and conta ct tip. Test w iredelivery at the torch; this mus t be reg ular.

Gas regulation

Chec k that Ar/CO 2 (80/20) ga s is us ed. Adjust the flow rate b e-tween 15 and 20 l/min to suit wire a nd joint configuration.Outdoors, use 20l. Make a short test run to assure no porosityarises from incorrect gas flow.Always c heck ga s flow w ith a flow meter which fits on the nozzle,to be sure that required gas flow is available.

2 3

Excessive space betw een wire guide tub es and rollers can

cause kinking of wire. Misalignment, also in the plane per-

pendicular to the one show n here, causes friction.

Inspect torch connec-

tions and c lean liner

weekly.

Correct location of wire guide tubes. Minimal space between

guide tub es and rollers. Proper alignment is essential.

Check gas pressure

and flow rate.

Replace worn contact tip.

Exit to torch

Exit to torch

concentric hole worn hole


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Gas cup and contact tip combination

It is es sential to mount the gas cup and conta ct tip at the rightdistance relative to ea ch othe r. The ideal 2mm distanc e isshown right.A larger distance increases stickout length, causing slag trapsand lack of fusion, ma inly in narrow joints.

Correct stickout length

The s tand -off, here a nd in other FILARC s ales literature refe rredto as s tickout, is the distance b etwe en the tip of the contac t tipand the w orkpiece. It must be he ld consta nt at 10 to 15mm forPZ6125 and related types in 1.0 and 1.2mm sizes and 15 to20mm for 1.6mm size.Correct, cons tant stickout length must be ma intained, as fa r asjoint preparation w ill allow. Variations w ill ca use arc voltageand welding current to fluctuate a nd in turn adversely influencedroplet trans fer.Overlong stickout results in larger droplets, causing spatter, alsoreducing gas protection, so bringing weld porosity.

Gas cup sizes

Various cup diameters mus t be ava ilable, to a llow s atisfac toryaccess to the joint, and maintain the stickout length recom-mended ab ove, acc ording to wire size.Small diameter gas cups are used for first layers only. Revertto the standard gas cup diameter when access to the weldjoint allows this, so full gas protection can be assured.Check gas flow after a change of gas cup size.

Trouble shootingPo rosity is normally the result of draught, the presence of con-dense wa ter, rust or paint on the plate ma terial or an overlongstickout length. Also insufficient gas flow, due to clogged gasnozzles is a common ca use. Check the ab ove, if porosity oc-curs.Unstable arc or large droplets are a sign of excessive stickout,possibly due to gas cup size not allowing suitable acc ess to

the joint; replac e ga s cup w ith smaller size.Also refer to the checklist of process faults and weld defectsas from page 26.

4 5

10-15mm

Ideal stickout length for 1.0

and 1.2mm wire sizes.

10-15mm>10-15mm

Correct. Smaller gas cup

diameter for 1stlayers of

join ts wit h lim ited acc ess.

Correct gas cup for

filling ensures goodgas protection and

correct stickout.

Incorrect. Too small gas cup

diameter for filling reduces

gas protection and brings

porosity.

Incorrect. Too large gas cup

diameter restricts access to

narrow joints, resulting in too

long stickout length.

2mm 10mm

Correct positioning

of contact tip.

Incorrect. Left: increased stickout caus-

es slag traps and fusion faults, mainly in

narrow joints. Right: contact tip extends

beyond g as cup. Risk of insufficient

shielding gas protection.


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Welding parameter setting

Arc voltage is related to w elding c urrent, which is es tablishedby the wire feed sp eed a djustment on the wire drive unit.

Note, the arc voltage setting for FILARC P Z6125 is higher than

usually required for norm al basic cored w ires.

AdviceAfter selecting the minimum choke va lue, s et the reco mmend-

ed a rc voltage (V) and wire feed se ttings /current values, s eefollowing pages for examples.Test weldab ility in the req uired w elding p osition. Po wer s our-ces fitted with voltage and current meters allow settings to bemonitored.Correct pa rameter setting w ill bring the a rc over the weld poo l,delivering either a smooth, fine droplet transfer at lower wirefeed speeds, o r spray arc at higher speeds.Too s hort or long arcs c an a rise from incorrect setting of pa ra-meters for the welding pos ition. To o btain co rrect results:

adjust the wire feed speed slightly.

If the arc length remains unsatisfactory, or weldability un-smooth,

adjust arc voltage in steps of 1 or 2V.

Results may be further improved by slight adjustment of wirefeed s peed/welding current.In case of continuing difficulty, especially at lower arc volt-ag e/welding currents, use a higher choke value and repeat theabove adjustments.Note, irregular w ire fee ding due to incorrect w ire d rive roller ad -justment, a damaged torch cable liner, or a worn contact tipcan c ause difficulties. Check thes e if weldability fluctuate s; a d-justment of welding parameters will not overcome theseequipment faults.

Arc Voltage and Welding Current MetersUsually fitted to pow er sources , these are helpful for training ormonitoring purpose s. They are not a subs titute for correct a d-justment of welding parame ters to suit the best comb ination of

wire size and w elding po sition.

8 9

Correct arc length.

Arc is just over weldpool,

with smooth droplets or

spray arc.

Arc length too short .

Stubbing. Wire dips into

weldpo ol, caused by

too high a wire speed

or too low an arc voltage.

Arc length too long.

Wire speed too low, or arc

voltage too high.


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Choice of wire size

FILARC P Z6125 and related types are a ll available in 1.0, 1.2and 1.6mm diamete rs, so allowing optimal productivity for var-ious combinations of plate thicknesses and welding positions.The chart oppos ite s hows recommended use.The 1.2mm size is recomme nded for general a ll-positional use.Diameter 1.6mm is a more productive choice w hen the major-ity of welding ta kes place in the dow nhand po sition.Although it is not recommended by FILARC, the 1.2mm size is

also an option when fabricato rs wish to weld root passes with-out ceramic weld metal support.The 1.0mm size is a dvanta geo us for pipe work and tubularcons tructions with minimal 10-12mm w all thickness and mini-mal 4inch d iameter, bringing exc ellent co ntrol of the we ld poolin the 3 to 9 o'clock pos itions.

Use with ceramic backingHigh quality root runs can be deposited economically whenusing ceramic weld metal support. Both the 1.2mm as well asthe 1.6mm size are very suited. Consult the special FILARCbrochure on ceramic backing materials.The 1.6mm size is very produc tive for root pas ses in the 1Gand 2G pos itions. The thick root pas s layer allows filling athigher welding currents.

Chart recommendationsare for a verage situations. There willbe exceptions for plate size, application area, etc. where the

versatility of PZ6125 will still provide excellent results.For add itional ad vice conta ct yo ur FILARC w elding e ngineer ornearest sa les office.A guide to ASME and EN welding po sitions is given on pa ge 15.

Wire 1.0mm 1.2mm 1.6mm

Welding Suitability for average applicationposition

Ro ot 1G /PA no t re co mm. o n b ac king o n b ac kingFill 1G /PA not recomm. yes yes

Ro ot 2G /P C no t re co mm. o n b ac king o n b ac kingFill 2G /P C not recomm. yes yes

Ro ot 3G /P F no t re co mm. o n b ac king no t rec omm.Fill 3G /P F yes yes not recomm.

Ro ot 4G /P E no t re co mm. no t re co mm. no t re co mm .Fill 4G /P E yes yes1 not recomm.

Ro ot 5G /P F no t re co mm. no t re co mm. no t re co mm.Fill 5G /P F yes poss ible1 not recomm.

Root 6GHL045 no t re co mm . no t re co mm . no t re co mm .

Fill 6GHL045 yes poss ible1 not recomm.

1F/PA poss ible2 yes yes

2F/P B poss ible2 yes yes

3F/P F not recomm. yes not recomm.

4F/P D not recomm. yes not recomm.

1 For thickness es be low 20mm, 1.0mm size is recomme nded2 1.2 or 1.6mm sizes will improve productivity.

10 11


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Recommended average

parameter settings

FILARC P Z6125, 1.0mm , neg ative () pola rity.

1G/PA Not reco mmended. Diameters 1.2 and 1.6mm are

best s uited.

FILARC PZ 6125, 1.2mm , neg ative () pola rity.

12 13

3G/PF Root : not recommendedFill : 140-160A/8.5-9.8m /min

18-21V

4G/PE Root : not recommendedFill : 130-150A/7.8-9.2m /min

18-19V

5G/PF Root : not recommendedFill : 130-160A/7.8-9.8m /min

18-19V

6G/HL045 Root : not recommendedFill : 140-150A/8.5-9.2m /min

18-20V

2G/PC Not reco mmended. Diameters 1.2 and 1.6mm arebest s uited.

3F/4F/PF/PD Fill : not recommended

1G/PA Ro ot*: 180-230A/8.0-11.0m /min22-28V (spray arc)

Fill : 240-320A/12.5-19.0 m/min28-34V

3G/PF Ro ot*: 150-180A/6.5-8.0m /min19-22V (spray arc)

Fill : 180-200A/8.0-9.5m /min22-25V

4G/PE Root : not recommendedFill : 130-150A/4.0-6.5m /min

18-19V

2G/PC Ro ot*: 170-230A/7.0-11.0m /min21-28V (spray arc)

Fill : 190-280A/9.0-16.0m /min23-33V

5G+6G/H-L000+H-L045 Root : not recommendedFill : 130-180A/4.0-8.0m /min

18-22V

* One-sided root pass on ceramic backing (round groove)

1F/2F/PA/PB 3F/4F/PF/PD

240-320A/

12.5-19 .0m/min

28-34V

3F:180-200A/8.0-9.5m /min

22-25V

4F:160-230A/6.5 -11.0 m/min/18-28V


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FILARC P Z6125, 1.6mm , negative () polarity. Generallyused for plate thickness of 20mm and higher.Also used with ceramic backing for plate thicknesses down to16mm.

With ceramic backing

ASME and EN Welding Positions

14 15

1G/PA Roo t*: 220-260A/4.0-5.0m/min26-28V (sp ray a rc)

Fill : 220-380A/4.5-12.0m/min27-36V

2G/PC Ro ot *: 200-240A/3.5-4.5m /min24-26V (sp ray a rc)

Fill : 240-270A/4.5-5.5m/min26-30V

1F/PA Fill : 240-380A/4.5-12.0m/min27-36V

Plate thickness 20mm

2F/PB Fill : 240-320A/4.5-8.0m/min30-35V

* One-sided root pass on ceramic backing (round groove)

1G /PA 2G /PC

3G /PF &PG 4G /PE

5G /P F &PG -H-L000 6G /H-L045

1F/PA 2F/PB

3F /P F &P G 4F/P D


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Welding advice

Following pages provide a dvice on w elding techniques for typ-ical applications, followed by troubleshooting for typical faults.

Welding characteristicsFILARC P Z 6125 has distinctive, but not difficult welding cha -racte ristics. These differ from conventiona l ba sic cored w ires,by way of :

Higher arc voltage w ith smoother droplet transfer. Semi-spray arc operat ion aids posit ional work. Greater tolerance for arc voltage/welding current setting. Warmer, more fluid w eldpool for higher penetration. F la t t er we ld beads . Less risk of fusion faults a nd s lag t raps . Le ss s la g . Grinding requirements considerably reduced.

These impressive adva ntag es, including welder comfort, willbring improved results when the welding guidelines are cor-rectly followed . So me training is ob viously needed to ga in fa-miliarity with the welding cha rac teristics o f the PZ 6125, also toavoid using methods a ssoc iated with rutile co red wires, or c on-ventional basic types where colder weld pools and short arcdip transfer lead to less favourable weldability.

Positive penetrationTo ensure positive penetration, and so a void the most commoncause of w eld defects :

Always try to weld backhand

This ensures good p enetration and p revents slag runningahea d of the w eldpool. See figure A.Forehand welding can deliver a reasonable appearance, butpenetration is often poor, due to the slag running a head of theweldpool. There is a lso the cha nce o f overflowing the w eld-pool, causing slag traps and lac k of fusion, see figure B.Correct torch angle is 70-90 as s how n figure A. At lower an-gles, see figure C, insufficient penetration and lack of fusioncan be expected.

16 17

Figure B

Forehand welding (pushing). Risk of insufficient penetration,

lack of fusion and slag traps.

Figure A

Corr ect bac khand w elding (trailing) with t orch at 70 -90.

Figure C

Backhand welding w ith too small a torch angle, causing insuf-

ficient penetration and lack of fusion.

direction of travel

direction of travel

direction of travel

70-90


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Torch positions for

positional welding

PZ 6125 and related types a re well suited for all-position w eld-ing. Following are typical situations where correct torch posi-tioning plays an important role in avoiding w eld defects.

2G/PCTorch position de pends o n plate thickness and bevel angle of

the joint. If the torch positions shown cannot be used, it is rec-ommended that the bevel angle is enlarged.Always maintain the torch angle of 70-90 relative to the w eldbea d and direction of travel as a dvised on page 17.Maintain a stea dy travel speed to a chieve a regular bea d thick-ness, without sagging.See page 22 for guidance on weaving.

18 19

B. Second layer, using flatter bead.

A . Root pass.

Without backing: grind oppo site side.

With backing: use round ceramic. Avoid overthick bead.

30

45

Avoid saggingSlag traps and fusion faults arise from sagging (rollover), typi-cally caused by:

Wrong travel speed.

Incorrect torch angle. Too high welding current. Wrong we ld bead s equ ence .

Sa gging requires grinding toeliminate weld d efects . Thiscan be avoided by keepingweld beads a s f lat as possibleas s hown by the diagrams, soreducing repair rates a nd un-productive grinding. w rong rig ht

Wea ving advice is given onpage 22.

C. Third layer builds up

weld thickness.

D. Fourth layer creates

favourable angle for

following pass.

E. Fifth layer. Not e how

layers are alwaysbuilt up from bottom

side of joint as weld

thickness increases.

10

45

10


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Torch positions, continued

3G/3F/PFNote the torch positions shown below for root run and fillinglayers.Jo int bevelling must a llow g ood a cces s to the root area. If nec-essary use a narrower gas cup.

4G/PEUse b as ic electrode or TIG-welding for root pas s. Use FILARCPZ 6125 and related types fo r filling.Figures A and B give ideal torch positioning.

20 21

A. Root pass

B. Filling layers

Weaving a dvice is given on page 22.

10

10

2F/PBFigures A and B show the ideal torch positioning, using thebackhand method recommended.

Trouble shootingFigures C and D show possible undercut and sagging faults,and possible ca uses .

C D

C Undercut: Welding c urrent too high. Arc voltage too high. Travel spee d too high. Arc too c lose to vertical plane. Torc h ang le () too small.

D Sagging: Welding c urrent to o high. Arc voltage too high. Torch a ngle () too big. Layer too thick.

A

80-90

B

90

A B

70 - 90

45

ceramic backing


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Weaving technique

Use o f correct we aving, in conjunction with the torch positionsdescribed on previous pages, will avoid weld defects and re-duce grinding req uirements.

1G/PA PositionRestrict weaving width; try to weld stringer beads as far aspossible. For K joints, shown, restricted weaving and correcttorch pos ition a re important.

The arc mus t point into the c orner betwe en plate ma terial andweld as illustrated below.

3G/PF PositionCorrect weaving technique is very important when weldingPZ 6125 in the 3G pos ition. Incorrect weaving ca n lead to we lddefects.Apply a little weaving; stop at the plate edges for approx. 2seconds to allow weld metal to solidify. Always ensure satis-factory side plate wetting, as shown figure A.

A. Correct Wea ve width 1.5-2.0cm.

Use an upward triangletowa rds the joint centre. Remain app roximately

2 seconds a t the plateedges.

Assure good side platewetting.

B. Incorrect Weave width co rrect

but wrong technique. Downward triangle

causes convex weldwith risk of s lag trapsand fusion faults.

C. Incorrect Insufficient wea ving,

giving a convex weld,slag traps a nd fusion

faults.

22 23

A.Correct Apply stringer beads as far

as po ssible. Correct torch pos ition. Weave as little as p oss ible. Backhand welding.

B. Incorrect Excessive weaving. Wrong torch position. Forehand welding.

2G/PC Position

A.Correct Torch po inted onto plate. Correct weaving width. Good wetting onto plate

edges and weld.

B. Incorrect Torch no t pointed o nto

plate. Excessive weaving.


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Grinding

Grinding requirements for PZ6125 welds are not excessivewhen the recommended welding techniques are applied.Avoid overgrinding, this c an ca use de fects.Also d o not create sharp edge s, leading to s lag traps and lackof fusion when filling.Remove only the most obvious irregularities, like sagging,starts, stops a nd undercut, always leaving smooth bea d con-tours.

A Correct. B Incorrect.

Sealing runsGrind before welding, as shown figure D, to create a smooth,slightly concave groove, giving easy access for the weldingtorch.

24 25

C Always grind s tarts and s tops.

D Correct.

E Incorrect.Grinding wheelpushed into root,bringing dee pgroove.The na rrow joint

is almost inac-cessible to thetorch.


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Trouble shooting/process faults

Although good equipment maintenance and proper weldertraining will help preventing process faults and weld defects,they can never be a voided completely. In such cas es, under-standing of the most common causes will lead the welder toquickly solving the problem encountered.Listed below are the most common process faults and theirlikely causes. For faults that result from incorrect setting orwrong welding techniques, we refer to previous chapterswhere co rrect ha ndling of FILARC P Z 6125 and relate d types isdes cribed in detail. Weld defec ts and their origins are dis-cussed on next pages .

Process faults Likely causes

1. w ire stub bing - pa ra meter s etting s

2. w ire b urn-b a ck - w ire re el b ra ke to o tig ht- parameter set t ings- damag ed/worn contact t ip- burn-back t ime too long

3. s pa tter - pa ra meter s ettings- wrong shielding g as/gas f low rate

too high, too low or irregular- irregular wire feed

- worn contac t t ip- paint, rust or dirt in joint area

4 . ir regular wire f eed/ - ro ll pres s ure t oo lowunstable arc/wire jam - damag ed/worn contact t ip

- wrong contact t ip s ize- overheated contact t ip- dama ged/worn/bent liner- dirty or rusty w ire/wire kinks- misalignment of rolls and

guide tubes /wo rn rolls- wire reel brake too tight- wire crossed on reel

(brake too loose)- irregular gas f low

Trouble shooting/weld defects

Lack of fusion defects. There are seve ral types of lac k of fu-sion defects, but all share the same fea ture that weld meta l andparent metal have not fused at o ne or more place s.Below , typical forms of lack of fusion are show n in a V-buttwe ld. They ca n equa lly occ ur in other butt-weld types . Alsoshown is a typical defect in fillet welds, w here the weld metalfails to fuse with, normally, the standing leg.

26 27

cold lap

lack of interrun fusion

lack of side wa ll fusion

lack of root fusion

lack of fusion

Possible causes RemediesGeneral

t ra ve l s pe ed to o h ig h - re du ce t ra ve l s pe ed /a llo w more dwell time at ed ges

w ro ng p a ra m et er s e tt in g - a d ju st p a ra m e te rs foreha nd w elding - b ac kha nd w eld ing , 70-90

torch angle

Lack of root fusion root g a p too s ma ll - enla rge ga p

Fillet: lack of fusion at standing leg

t o rch too much p oin ted a t - change t o rch o rien ta t ionhorizontal leg


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Lack of weld penetrationLack of penetration occ urs w hen the weld meta l fails to extendinto the complete root of a joint. Shown below are three typi-cal cases .

Possible causes RemediesGeneral

we ld ing cu rren t t oo low - increas e wire f eed/arc vo lt age a rc vo lta g e to o hig h - re duc e a rc vo lta g e t ra ve l s pe ed to o h ig h - re duc e t ra ve l s pe ed t ra ve l s pe ed to o lo w - in cre a se tra ve l s pe ed ; a vo id

slag running a head o f weld pool foreha nd w eld ing - ba ckha nd w eld ing t orc h a ng le to o sm a ll - us e 70-90 to rc h a ng le ; a im

the arc at the leading edge of

the pool

Butt welds

ro ot ga p to o sm all/ - inc re as e ga p/re duc e fa c eface too big

jo in t inc lud ed a ng le - inc re as e a ng le

Slag inclusionsSlag inclusions oc cur when molten slag is not a llowed to es-cape to the surface of the w eld pool, when the weld pool over-rides slag running a head of it , or when slag remainders a t thetoe of beads are not sufficiently remolten.

Possible causes Remedies

we ld ing cu rren t t oo low - increas e wire f eed/arc vo lt age

t ra ve l s pe ed to o lo w - in cre a se tra ve l s pe ed ; a vo idslag running a head o f weld pool

foreha nd w eld ing - ba ckha nd w eld ing t orc h a ng le t oo s ma ll - us e 70-90 to rc h a ng le ; ke ep

slag behind arc convex bea ds - increa s e a rc volta ge to o muc h w ea ving - red uc e tra ve l s pee d; when

possible use split-weavetechnique, otherwise reduceweaving width.Avoid thick laye rs.

Porosity.Possible causes Remedies dra ught /w ind - c los e doors or w indow s /

place wind screens pa int, g re as e o r d irt - c lea n pla tes

in the weld area ga s cup c logged - c lea n/repla c e ga s cup d is torted - repla ce g as cup to o s ma ll - repla ce with one suiting the

or too b ig joint geometry ga s flow too high - a djus t flow ra te

or too low g a s le aks in s ys te m - c he ck b y b lo cking ga s c up;

a s pira te a ir continued ga s flow ind ica tesleaks

water leaks in cooled guns - check connect ions g a s c up to w o rkp ie c e - c h ec k p o sit io nin g o f c o nt a ct t ip

dis ta nc e too long rela tive to g as c up;readjust parameters

Undercutting

Undercutting is g enerally ca used b y an excessive welding cur-rent or arc voltage, or may be the result of a too high travelspee d. To avo id this, low er wire feed s peed a nd/or travelspeed until satisfactory bead appearance is obtained. If un-dercutting a ppears a t one leg o f a fillet weld, the torch pos itionmay be wrong; try increasing the angle between torch and op-posite leg.

28 29

Examples of lack of root penetration


17/17




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