درمانگاه تخصصی و جوشکاری

درمانگاه تخصصی و جوشکاری

اسلاید 1: Welding Course 1Arc Welding Processes“In The Name of God”By: M. SeidiOct. 2007

اسلاید 2: Joining ProcessesMetallurgicalChemicalMechanicalScrew & RivetNail & PeenMineral & OrganicGlueWeldingBrazingIntroduction

اسلاید 3: Mechanical FasteningThreaded FastersBoltsScrewsNutsOther Fastening MethodsStaplingCrimpingSnap-in FastenersShrink and press fitsIntroduction: 1. Mechanical Joining Processes

اسلاید 4: Rivetsa) Solidb) Tubularc) Split (bifurcated)d) compressionIntroduction: 1. Mechanical Joining Processes

اسلاید 5: Design guidelines for riveting(a) Exposed shank is too long; the result is buckling instead of upsetting(b) Rivets should be placed sufficiently far from edges to avoid stress concentrationsIntroduction: 1. Mechanical Joining Processes

اسلاید 6: Design guidelines for riveting(c)Joined sections should allow ample clearance for riveting tools(d) section curvature should not interfere with the riveting processIntroduction: 1. Mechanical Joining Processes

اسلاید 7: Adhesive BondingProducts are joined and assembled by the use of AdhesivesAdhesives properties to be consideredStrengthToughnessResistance to various fluidsAbility to wet the surface to be bondedIntroduction: 2. Chemical Joining Processes

اسلاید 8: Types of adhesivesIntroduction: 2. Chemical Joining ProcessesProperty

اسلاید 9: Adhesive Peeling TestCharacteristic behavior of adhesive in a peeling test :(a) brittle adhesive (b) tough adhesiveIntroduction: 2. Chemical Joining ProcessesPeeling Force(a)(b)

اسلاید 10: Joint Design in Adhesive BondingIntroduction: 2. Chemical Joining ProcessesAdhesiveAdhesiveAdhesiveRivetSpot Welda. Poorb. Goodc. Very Goodd. Combination Joints

اسلاید 11: Configurations for adhesive bonds(a) Single lap(b) Double lapIntroduction: 2. Chemical Joining Processes

اسلاید 12: Configurations for adhesive bonds(c) Scarf (d) StrapIntroduction: 2. Chemical Joining Processes

اسلاید 13: Introduction: 3. Metallurgical Joining ProcessesJoiningSolid state weldingSoldering and brazingFusion weldingArc energy Chemical energyOther processes Non consumable electrode Consumable electrode Resistance welding Cold weldingFriction welding Diffusion weldingFlash weldingUltrasonic weldingExplosion weldingGas metal arc welding Shielded metal arc weldingSubmerged arc weldingFlux cored arc welding Electrogas weldingElectroslag welding Gas tungsten arc weldingAtomic hydrogen welding Plasma arc weldingOxyacetylene welding Oxyfuel gas weldingLaser beam weldingThermit weldingElectron beam welding…SolderingBrazing

اسلاید 14: Introduction: Arc Welding ProcessesElectric arc welding refers to a group of fusion welding processes that use an electric arc to produce the heat required for melting the metal.Advantages:Inexpensive power sourceRelatively inexpensive equipmentWelders use standard domestic current.Portable equipment is availableProcess is fast and reliableShort learning curveEquipment can be used for multiple functionsElectric arc heat is about 5,000 oC

اسلاید 15: All fusion welding process have thee requirements:HeatShieldingFiller metalThe method used to meet these three requirements is the difference between arc welding processes.In this class you will have the opportunity to use four arc welding processes:SMAWGMAWGTAWSAWIntroduction: Arc Welding Processes

اسلاید 16: Additional Electric Arc Welding Processes FCAW (Flux Core Arc Welding) ESW (Electroslag Welding) EGW (Electrogas Welding) PAW (Plasma Arc Welding) ASW (Arc Stud Welding)

اسلاید 17: Safe PracticesProtection from :Arc’s raysWelding fumesSparksContact with hot metal

اسلاید 18: Arc Welding Power SuppliesThe current for arc welder can be supplied by line current or an alternator/generator.Line current must be transformed:High voltage--Low amperage High amperage--low voltageThe type of and polarity of the welding current is one of the differences between the different arc welding processes.SMAWConstant current (CC), AC, DC+ or DC-GMAWConstant voltage (CV) DC+ or DC-GTAWConstant Current (CC) ), AC, DC+ or DC-Welding current differences can include: AmperageVoltagePolarityHigh frequency currentWave form

اسلاید 19: Considerations When Selecting an Arc Welding Power SupplyMaximum AmperageDuty cycleAmperage rangeAmperage adjustment mechanismInput power requirementsInitial cost and operating costSize and portabilityFuture needs for a power supplyAvailable skillsSafetyManufacturers supportOpen circuit voltage

اسلاید 20: Arc Welding Requirements

اسلاید 21: Amperage Output & Duty cycleOptimum output amperage is determined by:thickness of the metal,type of joint,welding positiontype of electrode.The amount of continuous welding time a power supply can be used is determined by the duty cycle of the power supply.Duty cycle is based on a 10 minute interval.Many power supplies have a sloping duty cycle.

اسلاید 22: Five Common Output Currents1. AC2. DC3. ACHF4. PC5. Square wave(Alternating Current)(Direct Current)(Alternating Current-High Frequency)(Pulsed Current)

اسلاید 23: Addition Features Available on Some Electric Arc Power Supplies:1. Remote control2. High frequency3. Wave balancing4. Voltage control

اسلاید 24: Electric Arc Welding Electrical TermsElectrical CircuitDirect current (DC)Alternating current (AC)AmpereVoltResistanceOhms LawConstant potentialConstant currentVoltage dropOpen circuit voltageArc voltagePolarityDual Control

اسلاید 25: Electrical CircuitAn electrical circuit is a complete path for electricity.When the arc is established, an electrical circuit is also completed.

اسلاید 26: Alternating CurrentThe type of current where the flow of electrons reverses direction (polarity) at regular intervals.Recommended current for general purpose electrodes and flat position.

اسلاید 27: Direct CurrentThe type of current where the flow of electrons (polarity) is in one direction.Controlling the polarity allows the welder to influence the location of the heat.When the electrode is positive (+) DCRP or DCEP it will be slightly hotter than the base metal.When the base metal is positive (+), DCSP or DCEN, the base metal will be slightly hotter than the electrode.DC current is required for some electrodes and recommended for out of position welding.

اسلاید 28: AmpereAmperes: the unit of measure for current flow.One ampere is equal to 6.24150948×1018 electrons passing by a point per second.Electricity passing through a resistance causes heat.An air gap is a high resistanceThe greater the amperage flowing through the resistance (air gap)--the greater the heat.The electrode also has resistance.Excessive amperage for the diameter of the electrode over heats the electrode. Insufficient amperage for the diameter of electrode makes electrode hard to start.

اسلاید 29: VoltThe volt is the measure of electromotive force.It is defined as the potential difference across a conductor when a current of one ampere dissipates one watt of power.The voltage at the electrode determines the harshness of the arc.Voltage is only adjustable in dual control machines.

اسلاید 30: ResistanceThat characteristic of a material that impedes the flow of an electrical current.Measured in units of Ohm’s (  )When ever an electrical current passes through a resistance heat is produced.Air is a high resistanceElectrical current passing through air produces a lot of heat.

اسلاید 31: Ohm’s LawOhms law states that, in an electrical circuit, the current passing through a material is directly proportional to the potential difference applied across them.Commonly expressed as:E=I.RCan also be used to teach electrical safety.Amperage is the harmful portion of electrical current.Rearranging Ohm’s Law for amperage shows that amperage (current flow) is determined by the voltage divided by the resistance:I=E/RThe higher the resistance, the less current that will flow for a given voltage.

اسلاید 32: Power SupplyThere are 2 different types of power supplies: Constant current Constant potential In a constant current power supply, the current (amperage) stays relatively constant when the voltage is changed.In a constant potential power supply, the voltage stays relatively constant when the amperage is changed.

اسلاید 33: Constant Current Power SupplyCharacteristics of constant current power supply:The machine provides a high voltage for striking the arc.Open circuit voltage (OCV)OCV is not adjustable for most machinesWhen the arc is struck the voltage drops to the welding voltage.Arc voltageArc voltage varies with the arc length.As the welding proceeds the current will not vary much as the arc length changes.

اسلاید 34: Increasing the voltage from 20 to 25 volts (25%) only decreases the amperage from 113 to 120 Amp (5.8%).Constant Current Power Supply-Cont.

اسلاید 35: Constant Potential Power SupplyThe constant potential power supply is modified to produce a relatively constant voltage as the amperage changes.Characteristic of GMAW power supplies.

اسلاید 36: Voltage DropVoltage drop is the reduction in voltage in an electrical circuit between the source and the load.Primary cause is resistance.When an excessive voltage drop exists, the electrical circuit will not perform as designed.Localized resistance (connection) can cause excessive heat.Excessive heat can cause component failure.When extra long welding loads are used, the amperage must be increased to have the same heat at the weld.

اسلاید 37: Dual ControlSome weldors have controls for both the voltage and the amperage.Operator can set the harshness of the arc (voltage) and the amount of heat (amperage) independent of each other.

اسلاید 38: Joints, Welds & PositionsButtLapTCornerEdgeElectric arc welding uses five types of joints, five types of welds and five positions.Five Joints:

اسلاید 39: Five types of weldsSurface WeldsGroove WeldsFillet WeldsPlug WeldsSlot Welds

اسلاید 40: 1. Surface WeldsSurface welds are welds were a material has been applied to the surface of another material. May or may not be blended with the work piece.Two common applications are for hard surfacing and padding.

اسلاید 41: 2. Groove WeldsGroove welds are used to fuse the sides or ends of two pieces of metal.The primary use of groove welds is to complete butt joints.

اسلاید 42: 3. Fillet WeldsFillet welds have a triangular cross section and are used to fuse two faces of metal that are at a 90 degree angle to each other.Lap JointOutside CornerT Joint

اسلاید 43: 4. Plug WeldsPlug welds are used to attach two surfaces together when a complete joint is not required and the design does not allow for any weld bead outside the dimensions of the metal.The holes can be made with a drill bit or punch.The weld is completed by establishing the arc on the bottom plate and then continuing to weld until the hole is full.

اسلاید 44: 5. Slot WeldsSlot welds are identical to plug welds except for the shape of the holes. For slot welds, slots are machined or stamped in the upper plate.They are complete the same as plug welds.

اسلاید 45: Joints, Welds & Positions HorizontalFlatVertical UpOverheadVertical Down

اسلاید 46: Weld NomenclaturePenetrationBeadBase metalJoint AngleReinforcementBeadRoot FaceExcessive PenetrationRoot Opening

اسلاید 47: Weld Nomenclature-cont.RootThroatFaceToeReinforcementLegLegToe

اسلاید 48: Weld Nomenclature-cont.Tack WeldRoot PassFiller PassCover PassIn multiple pass welds, each pass has a specific function.A tack weld is used to hold the joint at the desired gap.If it is not used, the heat of the weld will cause the joint to close.The filler pass is used to fill in the joint.A pattern bead or multiple stringer beads will be used.The root pass is used to fuse the root of the weld.If the root pass does not have adequate penetration, it must be cut or gouged out before the weld is completed.The cover pass doesn’t add very much strength to the weld. It is used for appearance and to fill in surface voids.

اسلاید 49: Bead PatternsHard SurfacingFiller passCover passReduce penetrationCommon patterns:CircleCrescentFigure 8Pattern beads are used whenever a wider bead is needed.

اسلاید 50: Protection of the Molten Weld PoolMolten metal reacts with the atmosphere:Oxides and nitrides are formedDiscontinuities such as porosityPoor weld metal propertiesAll arc welding processes employ some means of shielding the molten weld pool from the air.

اسلاید 51: Welding FluxThree formsGranularElectrode wire coatingElectrode coreFluxes melt to form a protective slag over the weld poolOther purposesContain scavenger elements to purify weld metalContain metal powder added to increase deposition rateAdd alloy elements to weld metalDecompose to form a shielding gas

اسلاید 52: Shielding GasShielding gas forms a protective atmosphere over the molten weld pool to prevent contamination.Inert shielding gases, argon or helium, keep out oxygen, nitrogen, and other gasesActive gases, such as oxygen and carbon dioxide, are sometimes added to improve variables such as arc stability and spatter reduction.ArgonHeliumOxygenCarbon Dioxide

اسلاید 53: Questions?Turn to the person sitting next to you and discuss (1 min.): What would happen if there was no flux on the wire to decompose into gas or no inert shielding gas was provided? What would the weld metal look like?

اسلاید 54: Shielded Metal Arc Welding (SMAW)

اسلاید 55: Shielded Metal Arc Welding Equipments

اسلاید 56: Magnetic Flux MotionConductorMagnetic flux lines

اسلاید 57: AWS SMAW Electrode Identification System Electrode StrengthPositionE X X X XCoating/Operating Characteristics

اسلاید 58: AWS SMAW Electrode Identification SystemE XX YYنشاندهنده الكترودE XX YYنشاندهنده مينيمم استحكام كششي فلزجوشE XX YYنشاندهنده وضعيت جوشكاريY=1قابل كاربرد در تمام وضعيت هاي جوشكاريY=2قابل كاربرد در وضعيت هاي تخت و افقيY=4قابل كاربرد در تمام وضعيت هاي جوشكاري و عمودي رو به پائينE XX YYنشاندهنده نوع پوشش الكترود جوشكاريY=0, 1پوشش سلولزيY=2, 3, 4پوشش روتيلي محتوي اكسيد تيتانيومY=5, 6, 8پوشش قليايي كم هيدروژنY=7پوشش اكسيديY=9پوشش خاص

اسلاید 59: Steel Alloy Suffixes for SMAW ElectrodesSuffixMajor Alloy Element(s) . A10.5% Molybdenium B10.5% Molybdenium + 0.5% Chromium B20.5% Molybdenium + 1.25% Chromium B31.0% Molybdenium + 2.25% Chromium B40.5% Molybdenium + 2.0% Chromium C12.5% Nickel C23.5% Nickel C31.0% Nickel D10.3% Molybdenium + 1.5% Manganese D20.3% Molybdenium + 1.75% Manganese G 0.2% Molybdenium + 0.3% Chromium + 0.5% Nickel + 1.0% Manganese + 0.1% Vanadium WWeathering Steel

اسلاید 60: AWS SMAW Electrode Classification ExampleE7018E indicates electrode70 indicates 70,000 psi tensile strength1 indicates use for welding in all positions8 indicates low hydrogenE7018-A1-H8 = ?

اسلاید 61: AWS Carbon and Low Alloy Steel Electrodes

اسلاید 62: ANSI/AWS - 5.1 : Specification for Covered Carbon SteelANSI/AWS - 5.5 : Specification for Low Alloy SteelANSI/AWS - 5.4 : Specification for Corrosion Resistant SteelAWS Website:http://www.aws.orgAWS: American Welding Society

اسلاید 63: Electrode Classification:1. Mandatory Part2. Arbitrary PartE AA BB C(C) DDD X Y (H) MandatoryArbitraryBritish Standard (BS) SMAW Electrode Identification System

اسلاید 64: i. Mandatory Part :E AA BB C(C)EIndicate Covered MMAW ElectrodeAAIndicate Yield Strength of Electrode Core (MPa)BBIndicate Electrode Elongation PercentC(C)Indicate Type of Covering:AAcidicOOxideARRoutile AcidicRRoutile (Medium Cover)BBasicRRRoutile (Thick Cover)CCellulosicSOther TypeBritish Standard (BS) SMAW Electrode Identification System

اسلاید 65: ii. Arbitrary Part :DDD X Y HDDDIndicate Nominal Electrode RecoveryXIndicate Electrode Usability:3. YIndicate Recommended Polarity and Voltage (Next Slide)4. HLow Hydrogen Electrodes1. All Positions2. All Positions Expect V-Down3. F for Groove and F, H, V for Fillet Welds4. F5. F, V-Down for Groove and H, V for Fillet Welds6. Other Position UsabilityBritish Standard (BS) SMAW Electrode Identification System

اسلاید 66: British Standard (BS) SMAW Electrode Identification SystemRecommended Ampere and Voltage TableCodePolarityMinimum Voltage1DCEN & DCEP 502DCEN503DCEP504DCEP705DCEN706DCEP707DCEN & DCEP908DCEN909DCEP90

اسلاید 67: British Standard (BS) SMAW Electrode Identification SystemExample:E 51 33 B 160 2 1 HECovered MMAW Electrode51Yield Strength (MPa)33Elongation PercentB Basic Cover160Electrode Recovery2 All Positions Expect V-Down0 DCEN With Minimum 50 VoltsH Low Hydrogen Cover

اسلاید 68: European Norm (EN) SMAW ElectrodesChemical Composition:

اسلاید 69: European Norm (EN) SMAW ElectrodesSymbols for Type of Electrode Covering:The type of covering of the electrodes determines to a large extent the usability characteristics of the electrode and the properties of the weld metal. Two symbols are used to denote the type of covering:- R :rutile covering- B :basic covering

اسلاید 70: European Norm (EN) SMAW ElectrodesMechanical Properties:

اسلاید 71: European Norm (EN) SMAW ElectrodesSymbols for Weld Metal Recovery:

اسلاید 72: European Norm (EN) SMAW ElectrodesSymbols for Welding Position:The symbol below for welding positions indicates the positions for which the electrode is tested in accordance with EN 1597-3:1:all positions;2:all positions, except vertical down;3:flat butt weld, flat fillet weld, horizontal vertical fillet weld;4:flat butt weld, flat fillet weld;5:vertical down and position according to symbol 3.

اسلاید 73: European Norm (EN) SMAW ElectrodesSymbols for Hydrogen Content:

اسلاید 74: European Norm (EN) SMAW Electrode Identification SystemExample:E CrMo1 B 4 4 H5ECovered MMAW ElectrodeCrMo1Chemical Composition (Table 1)B Type of Covering (Basic Cover)4 Recovery and Type of Current (Table 3)4 Welding Position (F Butt & F Fillet Welds)H5 Hydrogen Content (5 ml/100 gr. Weld Metal)

اسلاید 75: Coating Materials -Partial Lista. Arc StabilizersTitania TiO2b. Gas-Forming MaterialsWood Pulp,Limestone, CaCO3c. Fluxing agents Cryolite, Witherite, Flurspard. Slag-Forming MaterialsAlumina Al2O3 , TiO2 , SiO2 , Fe3O4e. Slipping Agents toClay , Talc, Glycerin Aid Extrusionf. Binding AgentsSodium Silicate , Asbestos ,Starch , Sugarg. Alloying and DeoxidizingSi, Al, Ti, Mn, Ni, Cr Elements

اسلاید 76: Materials Used in Coverings on Steel Electrodes for SMAWa. Arc Stabilizers:. Common Name Technical NameRemarks .1. TitaniaTiO2Frequently used from purified titanium oxide2. Potassium oxalateK2C2O4Infrequently used3. Lithium carbonateLi2CO3 Infrequently used

اسلاید 77: Materials Used in Coverings on Steel Electrodes for SMAWb. Gas-Forming Materials:. Common NameTechnical NameRemarks .1. CellulosePurified wood pulpPrinciple ingredient in C6H10O5 “cellulosic” electrodes2. Wood flour Raw wood pulpCnHnOn3. LimestoneCaCO3 Produces CO and CO2 during welding and forms basic slag

اسلاید 78: Materials Used in Coverings on Steel Electrodes for SMAWc. Fluxing Agents:. Common NameTechnical NameRemarks .1. Cryolite Na3AlFe6 Strong fluxing agent2. Barium fluorideBaF23. Lithium fluoride LiFVery effective flux4. Lithium chlorideLiClInfrequently used5. WitheriteBaCO3Generates CO and CO2 gases, but then becomes strong flux6. FlursparFluoriteStrong fluxing agentCaF2

اسلاید 79: Materials Used in Coverings on Steel Electrodes for SMAWd. Slag Forming Materials:. Common NameTechnical NameRemarks .1. Bauxite Alumina Raises melting temp. and increases viscosity of slag2. FeldsparAlkali type-KnNanAlSi3O8Plagioclases-CaAl2Si2O83. FluosparFluoriteMarkedly decreases CaF2viscosity of slag4. LimeniteFeTiO3Impure from of titanium oxide5. RutileTiO2(10%Fe)Unrefined form of titanium oxide. Mainstay of “rutile” elctrodes

اسلاید 80: Materials Used in Coverings on Steel Electrodes for SMAWd. Slag Forming Materials-Cont.:. Common NameTechnical NameRemarks .6. Silica Flour Cristobolite Strong acid slag former7. WollastoniteCalcium silicateCaSio38. DolomiteMagnesiteOften used for forming slag when melting steel in furnace, but seldom included in electrodes coverings9. ZirconiaZirconium oxideInfrequently usedZrO2

اسلاید 81: Materials Used in Coverings on Steel Electrodes for SMAWd. Slag Forming Materials-Cont.:. Common NameTechnical NameRemarks .10. Magnetite Iron oxide Magnetic iron oxideFe3O411. PericlaseMagnesium oxideRaises melting temp. and increases viscosity of molten slag12. PyrolusiteManganese dioxideMnO2

اسلاید 82: Materials Used in Coverings on Steel Electrodes for SMAWe. Slipping Agents to Aid Extrusion:. Common NameTechnical NameRemarks .1. Bentonite clayMontmorilloniteUsed where water of constitution can be tolerate2. Kaoline clayKaoliniteAl2Si2O5(OH)3. MicaMusoviteKAl2(Si3Al)O10(OH)24. TalcSoapstoneMg3Si4O10(OH)25. GlycerineGlycerolTrihydric alcholC3H5(OH)3

اسلاید 83: Materials Used in Coverings on Steel Electrodes for SMAWf. Binding Agents:. Common NameTechnical NameRemarks .1. Sodium silicateWater glassAgent most often usedNa2OnSiO2(OH)n2. Potassium silicateK2OnSiO2(OH)n3. AsbestosCrysotileImproves durability baked covering and mixes with slag when melted during welding4. DextrineStarch (C6H10O5)5. Gum arabicAcacia (CnOnHn)6. SugarCn(OH)n

اسلاید 84: Materials Used in Coverings on Steel Electrodes for SMAWg. Alloying and Deoxidizing Elements:. Common NameTechnical NameRemarks .1. FerrosiliconUsually Silicon is deoxidizer 50% Si + Feand alloying element2. FerroaluminumUsually Strong deoxidier 85% Al + Fe3. FerrotitaniumUsually Strong deoxidier and 40% Ti + Fegrain refining agent4. Zirconium alloy40% Zr + Deoxidier 40% Si + Fe5. ElectroMn = 100%Most common alloying manganeseelement6. Chromium metalCr = 100%7. FerromanganeseStd. type (80%Mn + Fe)

اسلاید 85: Typical Covering Formulas for Steel SMAW ElectrodesPart I: Material Formulas (Parts by Weight Percent)E 6010E 6012E 6020E 7015E 7018Cellulose255Limestone4030Fluorspar1510Rutile5520Titania12Asbestos151015108Iron oxide130Clay10552Iron Powder35Ferrosillicon22255Ferromanganese44644Sodium silicate60407025Potassium silicate25

اسلاید 86: Typical Covering Formulas for Steel SMAW ElectrodesPart II: Chemical Composition (Percent After Baking)E 6010E 6012E 6020E 7015E 7018CaO25.514.4TiO210.146.015.4CaF215.211.0SiO247.023.640.020.020.5Al2O35.02.32.82.0MgO3.22.02.81.22.0Na3AlF35.75.0FeO1.37.030.7Na2O5.12.43.31.7K2O1.2Si1.51.51.02.82.5Mn2.82.54.02.01.8Fe2.828.5CO & CO220.212.0Volatile Matter25.05.0Moisture4.02.00.50.10.1

اسلاید 87: SMAW AdvantagesEasily implementedInexpensiveFlexible Not as sensitive to part fit-up variances

اسلاید 88: AdvantagesEquipment relatively easy to use, inexpensive, portableFiller metal and means for protecting the weld puddle are provided by the covered electrodeLess sensitive to drafts, dirty parts, poor fit-upCan be used on carbon steels, low alloy steels, stainless steels, cast irons, copper, nickel, aluminum

اسلاید 89: Quality IssuesDiscontinuities associated with manual welding process that utilize flux for pool shieldingSlag inclusionsLack of fusionOther possible effects on quality are porosity, and hydrogen cracking

اسلاید 90: LimitationsLow Deposition RatesLow ProductivityOperator Dependent

اسلاید 91: Other LimitationsHeat of welding too high for lead, tin, zinc, and their alloysInadequate weld pool shielding for reactive metals such as titanium, zirconium, tantalum, columbium

اسلاید 92: Questions?Turn to the person sitting next to you and discuss (1 min.): Wood (cellulose) and limestone are added to the coating on SMAW Electrodes for gas shielding. What gases might be formed? How do these gases shield?

اسلاید 93: Electrode Required Test According to AWS

اسلاید 94: Electrode Required Test: Chemical AnalysisNote 9:The minimum completed pad size shall be at least four layers m height (H) with length (L) and width (W) sufficient to perform analysis, The sample for analysis shall be taken at least 1/4 in. (6.4 mm) above the original base metal surface.

اسلاید 95: Weld Block for Chemical AnalysisElectrode Required Test: Chemical Analysis

اسلاید 96: Electrode Required Test: Chemical AnalysisChemical Composition Requirements for Weld Metal

اسلاید 97: Electrode Required Test: Tension & ImpactTest Assembly Showing Location of Test SpecimenE7018MOrientation and Location of Impact Test SpecimenOrientation and Location of All-Weld Metal Tension Test Specimen

اسلاید 98: Tension Test Specimen:Electrode Required Test: Tension & ImpactTension Test Specimen for E 6022:

اسلاید 99: Electrode Required Test: Tension & ImpactTension Test Requirements:

اسلاید 100: Electrode Required Test: Tension & ImpactImpact Test Specimen:Impact Test Requirements:

اسلاید 101: Electrode Required Test: Fillet Weld TestPositions of Test Plates for Welding Fillet Weld Test Specimens

اسلاید 102: Electrode Required Test: Fillet Weld TestDimensional Requirements for Fillet Weld Usability Test SpecimenRequirements for Preparation of Fillet Weld Test Assemblies

اسلاید 103: Electrode Required Test: Fillet Weld TestAlternative Methods for Facilitating Fracture of the Fillet Weld

اسلاید 104: Electrode Required Test: Transverse Tension Test

اسلاید 105: Electrode Required Test: Bend Test

اسلاید 106: Grade 2Grade 1Electrode Required Test: Radiographic TestRadiographic Soundness Requirements

اسلاید 107: Electrode Required Test: Moisture Content TestPercent Moisture=(A-B)/Weight of SampleA:Final Weight of Moisture Absorb SystemB:Primary Weight of Moisture Absorb System

اسلاید 108: T=27°CRelative Humidity=80%T=9hrElectrode Required Test: Moisture Content TestMoisture Content Limits in Electrode Coverings

اسلاید 109: SMAW Technical Point