Welding and Cutting Processes

Module 2 Module 2 – Welding and Cutting Processes Module 2 – Welding and Cutting Processes

ƒ 2A – Introduction to Arc Welding Processes

ƒ 2B – Introduction to Non-Arc Welding Processes

ƒ 2C – Brazing and Soldering

ƒ 2D – Introduction to Cutting Processes

ƒ 2E – Welding Process Applications

2-2 Module 2 – Welding and Cutting Processes Module 2 Learning Objectives

ƒ Definitions and terminology associated with arc welding z Description of welding arcs z Arc welding power supply types and characteristics ƒ Basic operational concepts of SMAW, GTAW, GMAW, FCAW, SAW, ESW, and EGW welding ƒ Overview of sppgpgecialized welding processes including narrow groove welding, low hydrogen practices, overlays (HFWMO, CRWMO, structural) and stud welding ƒ Code requirements (essential, supplementary essentials, and non-essential variables) ƒ Welding Safety ƒ Practical Experience (SMAW, GTAW, and GMAW) ƒ Welding Process Demonstrations

2-3 Module 2 – Welding and Cutting Processes Module 2 Learning Objectives

ƒ Definitions and terminology associated with non-arc welding processes ƒ Descriptions and capabilities of non-arc welding processes ƒ Advantages, disadvantages, and applications of non-arc welding processes ƒ Important operating parameters of non-arc welding processes ƒ Safety issues ƒ Applicable codes, standards, and specifications ƒ Demonstrations

2-4 Introduction to Arc Welding Processes

Module 2A Module 2 – Welding and Cutting Processes Arc Welding Introduction Process Definition

ƒ Forms of arc welding vary by means of: z Controlling the arc z Shielding of the molten metal z Filler metal addition (if used) ƒ Upper: Standard terminology - AWS ƒ Lower: Commonly used trade names

SMAW FUSION WELDING EGW “Stick”

GMAW ARC WELDING ESW “MIG”

FCAW PAW “Flux Core” GTAW SAW “TIG” 2-6 Module 2 – Welding and Cutting Processes Arc Welding Introduction Basic Arc Welding Circuit

2-7 Module 2 – Welding and Cutting Processes Arc Welding Introduction Welding Arc

Welding Electrode Region

Work Electrode Region

2-8 Module 2 – Welding and Cutting Processes Arc Welding Introduction Electrode Types

ƒ Consumable Electrodes z Melt and transfer to the weld for filling joint Š Carbon steel Š Low-alloy steel Š Stainless steel Š Aluminum Š Magnesium Š Copper Š Titanium z Filler metal ƒ Nonconsumable Electrodes z Provide electrode for arc and do not melt Š Tungsten Š Carbon z Filler material, when used, is provided separately

2-9 Module 2 – Welding and Cutting Processes Arc Welding Introduction Consumable Electrode Classification (Filler Metal) ƒ Prefix z E = Electrode, R = Rod ƒ Carbon and Low Alloy Steels z First 2 or 3 digits indicate minimum UTS in KSI z Examples ER70S-1, E-7018 are 70 KSI UTS ƒ Other information mayypbe specified z Chemistry (ex. Cr, Mo, Mn, and Ni additions) z Process information (ex. S: solid, F: flux, T: tubular) z Primary welding positions ƒ Stainless Steels Use AISI Numbers ƒ Specific details contained in the electrode designation are dependent on the process

2-10 Module 2 – Welding and Cutting Processes Arc Welding Introduction Arc Welding Power Sources

ƒ Two types: constant voltage (CV) and constant current (CC) z Some power supplies are capable of both CC and CV operation

ƒ Constant voltage z Generally used with welding processes that employ a continuous ly fe d consuma ble electrode, typically in the form of wire (ex. GMAW, FCAW)

2-11 Module 2 – Welding and Cutting Processes Arc Welding Introduction Arc Welding Power Sources

ƒ Constant current z Slight variations in voltage due to changes in arc length have a minimal effect on current z Generally used for manual welding with a covered electrode or a tungsten electrode, where variations in arc (CC) length are unavoidable (ex. SMAW, GTAW) Š When used in a semi-automated or automated application, external control devices are needed (ex. GMAW, FCAW)

2-12 Module 2 – Welding and Cutting Processes Arc Welding Introduction Primary Operating Parameters

ƒ Arc Voltage/Arc Length ƒ Arc Current ƒ Electrode Feed Rate (Consumable) ƒ Welding Travel Speed ƒ Polarity

2-13 Module 2 – Welding and Cutting Processes Arc Welding Introduction Arc Voltage

ƒ Mainly related to arc length ƒ Affects concentration of arc heat z Shorter arc, more heat concentration z Longer arc, less heat concentration ƒ Voltage can be regulated to control arc length ƒ Varies little with arc current and welding speed z Has little affect on energy input and amount of melting ƒ Typical arc voltages: 8- to 40-volts

2-14 Module 2 – Welding and Cutting Processes Arc Welding Introduction Arc Current

ƒ Mainly affects amount of arc heat ƒ Determines electrode melting rate (consumable) ƒ Directly affects energy input to work and melting z More current, more melting z Less current, less melting ƒ Often regulated to control arc and energy input ƒ Arc currents: 1- to 1000-amperes z More typically, 50- to 500-amperes

2-15 Module 2 – Welding and Cutting Processes Arc Welding Introduction Electrode Feed Rate

ƒ Directly determines amount of metal deposited ƒ Closely related to current z Current must provide equal melt-off rate ƒ May be supplied manually or via an automatic feed system ƒ Typically, 10’s to 100’s of inches-per-minute (ipm)

2-16 Module 2 – Welding and Cutting Processes Arc Welding Introduction Welding Travel Speed

ƒ Has little affect on arc and electrode melting ƒ Directly affects metal deposition per length of weld ƒ Mainly affects energy input to work z Faster travel, less energy input and base metal melting z Slower travel, more energy input and base metal melting ƒ An important parameter to productivity ƒ May be provided manually or mechanized ƒ Typical range is 5- to 100-in/min

2-17 Module 2 – Welding and Cutting Processes Arc Welding Introduction Energy Input

2-18 Module 2 – Welding and Cutting Processes Arc Welding Introduction Electrical Polarity

ƒ Electrical polarity is important to arc operation ƒ Electrode positive z DCEP z DCRP (reverse polarity) ƒ Electrode negative z DCEN z DCSP (straight polarity) ƒ Alternating polarity z AC z VP (variable polarity)

2-19 Module 2 – Welding and Cutting Processes Arc Welding Introduction The DCEN Arc

2-20 Module 2 – Welding and Cutting Processes Arc Welding Introduction The DCEP Arc

2-21 Module 2 – Welding and Cutting Processes Arc Welding Introduction Need for Shielding from Atmosphere

ƒ Molten metal reacts with the atmosphere to form oxides and nitrides z Porosity can result z Metallurgical changes can occur ƒ Weld mechanical properties are generally reduced

ƒ Note that the weld should be free of dirt, grease, paint, scale, and other foreign objects to ensure weld quality z Fluxes and shielding gasses are not designed to scavenge these components from the solidifying weld metal

2-22 Module 2 – Welding and Cutting Processes Arc Welding Introduction Flux Shielding

ƒ Provides a gas to shield the arc and prevent excessive atmospheric contamination of the molten filler metal and weld pool. ƒ Provides scavengers, deoxidizers, and fluxing agents to cleanse the weld and prevent excessive grain growth in the weld metal. ƒ Establishes the electrical characteristics of the electrode. ƒ Provides a slag blanket to protect the hot weld metal from the air and enhance the mechanical properties, bead shape, and surface cleanliness of the weld metal. ƒ Provides a means of adding alloying elements to change the mechanical properties of the weld metal.

2-23 Module 2 – Welding and Cutting Processes Arc Welding Introduction Welding Fluxes

Ingredient Function Iron oxide Slag former, arc stabilizer Titanium oxide Alloy Calcium fluoride Slag former, arc stabilizer Magnesium oxide Fluxing agent Potassium silicate Slag, binder , fluxing agent Other silicates Gas former, arc stabilizer Calcium carbonates Gas former Cellulose Alloy, deoxidizer Ferro-chrome Alloy Other carbonates Gas former Ferro-manganese Alloy Ferro-silicon Deoxidizer

2-24 Module 2 – Welding and Cutting Processes Arc Welding Introduction Gas Shielding

ƒ Mainly purges the weld area to shield it from the atmosphere ƒ Argon is the most common inert gas ƒ Carbon dioxide is sometimes used z Less expensive z Similar to gases produced from fluxes ƒ CO2 and O2 are commonly mixed with argon z Oxidation stabilizes arc and metal transfer z Improves weld bead wetting ƒ H2 can be added to increase arc heat in some cases ƒ Helium may also be used to increase arc heat ƒ Require addition of deoxidizers to filler materials

2-25 Module 2 – Welding and Cutting Processes Arc Welding Introduction Sources of Shielding

2-26 Module 2 – Welding and Cutting Processes Arc Welding Safety Arc Welding Hazards

ƒ Arc Radiation z UV damage to skin and eyes ƒ Electrical Shock z Welding voltages are generally safe z Anomalous conditions can arise ƒ Fumes and Gases z Suffocation z Long term breathing of fume ƒ Compressed Gases z Explosion of cylinders ƒ Burns - Hot Metal ƒ Fire - Ignition of Nearby Flammable Materials

2-27 Module 2 – Welding and Cutting Processes Arc Welding Safety Arc Welding Safety

ƒ AWS Z49.1: 2005 z Safety in Welding, Cutting, and Allied processes z Training (mandated under provisions of the U.S. Occupational Safety and Health Act (OSHA), especially those of the Hazard Communication Standard, 29 CFR 1910.1200) ƒ Management Support ƒ VtiltiVentilation ƒ General Housekeeping ƒ Eye and Skin Protection from Radiation ƒ Hot Work Permit System

Reference: AWS Z49-1 or WHB, V1, Ch16 2-28 Module 2 – Welding and Cutting Processes Arc Welding Safety ANSI/ASC Z49.1 Safety in Welding, Cutting and Allied Processes ƒ A document outlining safe practices for welding and cutting operations ƒ Is referenced almost in all AWS welding codes ƒ When the code is mandated by the contract or laws, ANSI/ASC Z49.1 is also invoked.

2-29 Module 2 – Welding and Cutting Processes Arc Welding Safety Management Support

ƒ Evidenced by: z Stating clear safety objectives z Showing commitment to safety z Designating safe work areas z Developing safety procedures z Providing safe equipment z Implementing safety training

2-30 Module 2 – Welding and Cutting Processes Arc Welding Safety Personal Protective Equipment

ƒ Sturdy boots, no laces ƒ Clean clothing ƒ Woolen is best ƒ Treated cotton acceptable ƒ No synthetics ƒ PtPants with ithtffout cuffs ƒ Pants outside boots ƒ Flaps on shirt pockets ƒ Cap ƒ Gloves ƒ Leathers

2-31 Module 2 – Welding and Cutting Processes Arc Welding Safety Eye, Ear, Face, and Head Protection

2-32 Module 2 – Welding and Cutting Processes Arc Welding Safety Lens Shade Selector

2-33 Module 2 – Welding and Cutting Processes Arc Welding Safety Fume Exposure and Ventilation

Fume Plume

note head position

2-34 Module 2 – Welding and Cutting Processes Arc Welding Safety Welding in Confined Space

2-35 Module 2 – Welding and Cutting Processes Arc Welding Safety Shield Gases

ƒ Argon, Helium – Inert ƒ Nitrogen, Carbon dioxide – Reactive ƒ Odorless ƒ Colorless ƒ Can displace oxygen

2-36 Module 2 – Welding and Cutting Processes Arc Welding Safety Safe Welding and Cutting of Containers

Manifold/Piping System Compressed Gas

2-37 Module 2 – Welding and Cutting Processes Arc Welding Safety Compressed Gases Cylinder Safety

Oxygen Manifold System Acetylene Manifold System - Oxygen Supports Combustion – A Fuel Gas

2-38 Arc Welding Power Sources

Module 2A.1 Module 2 – Welding and Cutting Processes Arc Welding Power Sources Arc Welding Power Source

ƒ Provide suitably conditioned electrical power for the arc z Reduce line voltage to arc voltage z Provide suitable output characteristic for a stable arc ƒ Allow operator input of weld parameters/sequences ƒ Interfaces to/from other equipment z Wire feeders z Controllers z Robot systems

2-40 Module 2 – Welding and Cutting Processes Arc Welding Power Sources Sources of Electricity

ƒ Engine driven generator/alternator ƒ Utility power

2-41 Module 2 – Welding and Cutting Processes Arc Welding Power Sources Usable Arc Welding Voltage, Current Range

ƒ Industrial line voltages are 208VAC to 480VAC ƒ Voltage range for a welding arc is 20V to 80V ƒ Welding power sources need a transformer to convert line voltage to welding voltage ƒ Motor driven generators (for field use) directly output voltages that are usable for arc welding ƒ Typical welding arc currents range from 100A to 1000A ƒ 2kVA to 80kVA of electrical power is needed

2-42 Module 2 – Welding and Cutting Processes Arc Welding Power Sources Arc Welding Power Source Characteristics

ƒ Type of current z Transformers - AC z Transformers with rectifiers - AC/DC ƒ Welding current rating ƒ Duty cycle ƒ Service classification ƒ Input power requirements ƒ Special features z Remote control z High frequency z Pulsation z Start and finish schedules z Wave balancing and line voltage compensation

2-43 Module 2 – Welding and Cutting Processes Arc Welding Power Sources Line-Powered Welding Power Source Components

Arc Welding Power Source Fused Disconnect Switch (open) Electrode Input AC

Reduce Control Output Voltage Characteristics

Chassis Ground Connections

Earth Ground

2-44 Module 2 – Welding and Cutting Processes Arc Welding Power Sources Basic Characteristics of Power Sources

ƒ Constant Current z Transistor switching inverter supplies provide a relatively constant current at a given setting VOLTAGE

CURRENT Arc Force ƒ Constant Voltage Adjustment z Voltage remains relatively stable and current varies to maintain an arc voltage VOLTAGE

CURRENT 2-45 Module 2 – Welding and Cutting Processes Arc Welding Power Sources Output Control Methods

ƒ Transformers z Tapped secondary z Movable coil or shunt ƒ Reactor (inductor, older technology) z Movable reactor core z Saturable reactor (magnetic amplifier) ƒ Silicon Controlled Rectifier (SCR, newer technology) ƒ Transistor (newest technology) z Linear z Switching - inverter

2-46 Module 2 – Welding and Cutting Processes Arc Welding Power Sources Other Features

ƒ Single phase ƒ Three phase ƒ Remote control ƒ Pulsation ƒ Variable polarity AC ƒ Hig h frequency ƒ Synergic controls ƒ Start control ƒ Arc force control ƒ Finish - down slope

2-47 Shielded Metal Arc Welding (SMAW)

Module 2A.2 Module 2 – Welding and Cutting Processes Shielded Metal Arc Welding Elements of a Typical Welding Circuit for SMAW

Source: AWS Handbook, 9th ed., Vol. 2

2-49 Module 2 – Welding and Cutting Processes Shielded Metal Arc Welding Definition of SMAW

ƒ An arc welding process in which coalescence of metals is produced by heat from an electric arc that is maintained between the tip of a covered electrode and the surface of the base metal in the joint being welded

Source: AWS Handbook 9th ed. Vol. 2 2-50 Module 2 – Welding and Cutting Processes Shielded Metal Arc Welding SMAW

Medium arc length Long arc length

170A, 12V, T=5.5 IPM 170A, 14V, T=5.5 IPM

6012 electrode was used Recording rate was 125 frames per second

2-51 Module 2 – Welding and Cutting Processes Shielded Metal Arc Welding Electrode Covering

ƒ Depending on the type, the covering performs one or more of the following: z Provide a gas cover to shield the arc and prevent excessive atmospheric contamination of the molten filler metal z Provide scavengers, deoxidizers, and fluxing agents to cleanse the weld and (potentially) prevent excessive grain growth in the weld metal z Establishes the electrical characteristics of the arc. z Provides a slag blanket to protect the hot weld metal from the air and enhance the mechanical properties, bead shape, and surface cleanliness of the weld metal z Provides a means of adding alloying elements to weld metal to alter the microstructure and mechanical properties of the weld metal

2-52 Module 2 – Welding and Cutting Processes Shielded Metal Arc Welding Characteristics of SMAW

ƒ Outgrowth of original welding process developed in the early 20th century ƒ Most widely used process worldwide ƒ Normally performed manually by skilled welders ƒ Equipment and consumable costs are low ƒ Extremely versatile ƒ Productivity is low ƒ Fume generation rates are high ƒ Generally considered “low tech”

2-53 Module 2 – Welding and Cutting Processes Shielded Metal Arc Welding SMAW Advantages

ƒ Most widely used process worldwide – broad skill-base ƒ Equipment and consumable costs are low – “low-tech” ƒ Extremely versatile ƒ Easily implemented for field welding ƒ Relatively adaptable to part fit-up variances z Operator skill is required

Underwater welding with SMAW

2-54 Module 2 – Welding and Cutting Processes Shielded Metal Arc Welding Limitations

ƒ Requires relatively high- skilled manual welder ƒ Deposition rate is low ƒ Defect rates are relatively high ƒ Fume generation rates are high

2-55 Module 2 – Welding and Cutting Processes Shielded Metal Arc Welding Effect of Welding Parameters on Bead Profile

A) Proper amperage, arc length, and travel speed B) Amperage too low C) Amperage too high D) Arc length too short E) Arc length too long F) Travel speed too slow G) Travel speed too fast

Courtesy AWS Handbook, 8th Edition, Volume 2, page 64

2-56 Module 2 – Welding and Cutting Processes Shielded Metal Arc Welding Orientation of the Electrode

Courtesy AWS Handbook, 8th Edition, Volume 2, page 66

2-57 Module 2 – Welding and Cutting Processes Shielded Metal Arc Welding Typical Electrode Orientation and Welding Technique for Carbon Steel Electrodes

* Travel angle may be 10- to 30-degrees for electrodes with heavy iron powder coatings

From AWS Handbook, 8th Edition, Volume 2, page 65

2-58 Module 2 – Welding and Cutting Processes Shielded Metal Arc Welding Recommended Dimensions of Grooves for Shielded Metal Arc Welding of Steel

From AWS Handbook, 8th Edition, Volume 2, page 59 2-59 Module 2 – Welding and Cutting Processes Shielded Metal Arc Welding AWS A5.1 Specification for Carbon Steel Electrodes for SMAW ƒ E-XXXX z E = Electrode (coated) z First 2 digits = Ultimate tensile strength (UTS) in ksi z Third digit = position Š 1 is all positions Š 2 is flat or horizontal Š 4 is flat, overhead , horizontal or vertical-down z Fourth digit = type of coating Š 0 is DCEP Cellulose-sodium silicate Š 1 is AC/DCEP, Cellulose, potassium Š 2 is AC/DCEN, Rutile, sodium Š 3 is AC/DC, Rutile, potassium Š 4 is AC/DC, Rutile/iron powder Š 5 is DCEP, Lime, sodium Š 6 is AC/DCEP, Lime, potassium Š 7 is AC/DC, Iron oxide/iron powder Š 8 is AC/DCEP, lime/iron powder 2-60 Module 2 – Welding and Cutting Processes Shielded Metal Arc Welding SMAW Electrode Classification Example

ƒ E7018 z “E” indicates “stick” electrode z 70 indicates nominal tensile strength of 70-ksi z 1 indicates use for welding in all positions z 8 indicates low hydrogen coating ƒ E6010 z “E” indicates “stick” electrode z 60 indicates nominal tensile strength of 60-ksi z 1 indicates use for welding in all positions z 0 indicates cellulose coating

2-61 Module 2 – Welding and Cutting Processes Shielded Metal Arc Welding AWS A5.4 Specification for Stainless Steel Electrodes for SMAW ƒ Uses AISI number to denote alloy and suffix for coating type z -15 = DCEP z -16 = AC/DC ƒ Examples z E-308-15 is a 308 alloy with DCEP lime coating z E-312-16 is a 312 alloy with AC/DC rutile coating

2-62 Module 2 – Welding and Cutting Processes Shielded Metal Arc Welding AWS A5.5 Specification for Low Alloy Steel Covered Electrodes ƒ Similar to AWS A5.1 ƒ May be five digits ƒ Suffix denotes type of alloy z A C-Mo z B Cr-Mo z C Ni z D Mn-Mo ƒ E-8018-B2 z E Ni-Mo z 80,000-ksi UTS z G General z All positions z M Military z Alloyed with Cr-Mo z W Weathering z Lime, AC/DC

2-63 Module 2 – Welding and Cutting Processes Shielded Metal Arc Welding ASME Classifications

ƒ ASME classifies electrodes by F-No. and ASME Specification z The same F-No. are electrodes with the same usability characteristics Š All cellulosic electrodes are F-No. 3 Š All low-hydrogen electrodes are F-No. 4 z ASME specifications are the same as AWS specifications with the addition of “SF” Š AWS Specification A5 .1 is ASME Specification SFA -515.1

ƒ Electrodes can be in the same ASME specifications but in different F-no. groups and vice versa z E6010 is SFA-5.1 and F-No. 3 z E7018 is SFA-5.1 and F-No. 4 z E8018-B2 is SFA-5.5 and F-No. 4

2-64 Module 2 – Welding and Cutting Processes Shielded Metal Arc Welding Quality Issues

ƒ Discontinuities associated with manual welding process that utilizes flux for pool shielding z Slag inclusions z Lack of fusion ƒ Other possible effects on quality are porosity and hydrogen cracking

Lack-of-fusion defects in two-sided SMA weld

2-65 Module 2 – Welding and Cutting Processes Shielded Metal Arc Welding Low Hydrogen Practice

ƒ Hydrogen embrittlement is a common problem in medium- and high-carbon steel alloys z Causes delayed cracking in HAZ z Worse in thick sections, restrained parts ƒ Low hydrogen welding practices keep electrodes and weldment dry, prevent introduction of hydrogen into the weld metal z Preheat, minimum interpass temperatures ƒ Rod ovens and portable rod containers prevent moisture from being absorbed in electrode coatings

2-66 Module 2 – Welding and Cutting Processes Shielded Metal Arc Welding ASME Section IX – SMAW Process Procedure Variables

Supplementary Paragraph Brief of Variables Essential Essential Nonessential .4 φ F-Number X .5 φ A-Number X .6 φ Diameter X .7 φ Diameter > 1/4 in. X .12 φ Classification X QW-404 Filler .30 φ t X Metals .33 φ Classification X

2-67 Module 2 – Welding and Cutting Processes Shielded Metal Arc Welding ASME Section IX – SMAW Process Procedure Variables

Supplementary Paragraph Brief of Variables Essential Essential Nonessential .1 + Position X

QW-405 .2 φ Position X Positions .3 φ ↑↓ Vertical Welding X .1 > Heat Input X QW-409 Electrical .4 φ Current or Polarity X X Characteristics .8 φ I & E Range X

.5 φ Method of Cleaning QW-410 Technique .25 φ Manual or Automatic X

2-68 Gas Tungsten Arc Welding (GTAW)

Module 2A.3 Module 2 – Welding and Cutting Processes Gas Tungsten Arc Welding GTAW Process Description

ƒ An arc is formed between a nonconsumable (tungsten) electrode and the workpiece electrode ƒ The energy from the arc melts the workpiece, and the molten metal solidifies to form a weld bead ƒ Shielding gas provides the medium for arc formation and ppprotects the molten pool and electrode from oxidation

2-70 Module 2 – Welding and Cutting Processes Gas Tungsten Arc Welding Basic Components of GTAW

Source: AWS Handbook 9th ed. Vol. 1 2-71 Module 2 – Welding and Cutting Processes Gas Tungsten Arc Welding Autogeneous GTAW

Recording rate was 125 Hz

250A 11.5V 10 IPM

170A 10.5V, T=5.5 IPM 170A 11.5V, T=5.5 IPM

2-72 Module 2 – Welding and Cutting Processes Gas Tungsten Arc Welding GTAW Filler Metal

Good wire position

Recording rate: 250 Hz

170A 14.5V 5.5 IPM 35.4 IPM

Bad wire position – off target Bad wire position – too high

170A 12.5V 5.5IPM 35.4 IPM 170A 16.5V 5.5 IPM 35.4 IPM 2-73 Module 2 – Welding and Cutting Processes Gas Tungsten Arc Welding GTAW - Range of Operation

ƒ Current: <1- to 500-amps, typically 30 to 150 ƒ Voltage: 9- to 20-volts, typically 10- to 12-volts for argon ƒ Arc Gap: 0.02- to ¼-in., typically 1/16-in. ƒ Welding Speed: 1- to 40-in/min, typically 3- to 6-in/min. ƒ Shielding Gas: argon, argon hydrogen mixtures, helium, argon helium mixtures ƒ Thickness: 0.004-in. upwards, typically up to 0.1-in. in a single pass or ¼-in. with multiple passes ƒ May be without filler (autogenous) or with added filler, usually as wire, 1/32- to 3/32-in. diameter

2-74 Module 2 – Welding and Cutting Processes Gas Tungsten Arc Welding GTAW Process Description: Terminology

ƒ Gas Tungsten Arc Welding: GTAW - AWS Definition ƒ Tungsten Inert Gas Welding: TIG - Europe and worldwide, also often used in the U.S. ƒ Wolfram Inert Gas Welding: WIG - Used in Germany ƒ Heliarc: Original name in U.S. ƒ Argonarc: Original name in U. K.

2-75 Module 2 – Welding and Cutting Processes Gas Tungsten Arc Welding GTAW Applications

ƒ Full penetration welds, typically up to 0.1-in. ƒ Root runs, particularly in pipe welds ƒ Autogenous welds (no filler) ƒ High quality welds ƒ Fill runs, typically up to 0.5-in. ƒ MtMost met tlals z Stainless steels and nickel-based alloys z Carbon and low alloy steels z Aluminum and magnesium alloys z Titanium and reactive metals

2-76 Module 2 – Welding and Cutting Processes Gas Tungsten Arc Welding GTAW Applications

ƒ Small components - sensors, medical and electronic ƒ Tube to tube welds, orbital or rotated tube ƒ Tube to tube plate welds, condensers, heat exchangers ƒ Repairs, all industries (e.g., aerospace) ƒ Process equipment, food industry ƒ Claddi ng, over lays ƒ Sheet metal applications

2-77 Module 2 – Welding and Cutting Processes Gas Tungsten Arc Welding GTAW Process Advantages

ƒ Can be used in all positions, manual or mechanized ƒ Provides excellent control on thin and intricate parts ƒ No slag or spatter; post weld cleaning often not required ƒ Use with or without filler wire ƒ Welds almost all metals ƒ PiPrecise con tlfldhttrol of weld heat ƒ High quality

2-78 Module 2 – Welding and Cutting Processes Gas Tungsten Arc Welding GTAW Process Limitations

ƒ Lower deposition rates than consumable electrode processes ƒ Requires more dexterity and coordination for manual welding than consumable electrode processes ƒ Requires high gas purity, low tolerance for drafty environments means it cannot be used outdoors without spppecial precautions ƒ Low tolerance to contaminants ƒ Generally requires arc starting system ƒ Requires precise positioning of electrode

2-79 Module 2 – Welding and Cutting Processes Gas Tungsten Arc Welding Characteristics of Current Types for GTAW

Current type DC DC AC (balanced)

Electrode polarity Negative positive balanced

Electrode and ion flow

Penetration characteristics

Oxide cleaning No Yes Yes-once every half cycle action Heat balance in the 70% at work end; 30% 30% at work end; 70% at 50% at work end; 50% at arc (approx.) at electrode end electrode end electrode end penetration Deep; narrow Shallow; wide medium Excellent Poor Good Electrode capacity e.g.1/8in-400A e.g.1/4-120A e.g.1/8in-225A

Courtesy of the AWS Welding Handbook Volume 2, 7th Edition

2-80 Module 2 – Welding and Cutting Processes Gas Tungsten Arc Welding Shielding Gas for GTAW

ƒ Argon is used most extensively z Lower cost and flow rate than helium z Easier arc starting z Better cross draft resistance ƒ Helium is preferred for some applications z Transfers more heat to workpiece - useful for metals with high thermal conductivity and for high speed welding z Argon-helium mixtures are used to gain advantages of both gases ƒ Argon-Helium mixtures z Used to increase penetration on stainless steels, along with up to 15% hydrogen

2-81 Module 2 – Welding and Cutting Processes Gas Tungsten Arc Welding Pulsed Gas Tungsten Arc Welding

2-82 Module 2 – Welding and Cutting Processes Gas Tungsten Arc Welding Hot Wire GTAW

2-83 Module 2 – Welding and Cutting Processes Gas Tungsten Arc Welding High Frequency (HF) Arc Starting

ƒ Spark gap oscillator generates HF (VRMS ~ 3500 V, f ~ 10kHz) ƒ Air core transformer couples HF to welding electrode ƒ HF bypass filter prevents HF current from passing back into welding machine (and causing possible damage to electronics 2-84 Module 2 – Welding and Cutting Processes Gas Tungsten Arc Welding Specifications and Practices

ƒ Electrode and filler metal specifications z AWS A5.12, Specification for Tungsten and Tungsten Alloy Electrodes for Metal Arc Welding and Cutting z AWS A5.18, Specification for Carbon Steel Filler Metals for Gas Shielded Arc Welding z ASME uses the same labeling system for GTAW filler metals as SMAW electrodes Š SF labeling ƒ Recommended practice documents ƒ C5.5, Recommended Practices for Gas Tungsten Arc Welding ƒ C5.10, Recommended Practices for Shielding Gases for Arc Welding and Cutting

2-85 Module 2 – Welding and Cutting Processes Gas Tungsten Arc Welding ASME Section IX – GTAW Process Procedure Variables

Supplementary Paragraph Brief of Variables Essential Essential Nonessential .3 φ Size X .4 φ F-Number X .5 φ A-Number X .12 φ Classification X .14 ± Filler X .22 ± Consumable Insert X .23 φ Filler Metal Product Form X .30 φ t X QW-404 Filler .33 φ Classification X Metals .50 ± Flux X

2-86 Module 2 – Welding and Cutting Processes Gas Tungsten Arc Welding ASME Section IX – GTAW Process Procedure Variables

Supplementary Paragraph Brief of Variables Essential Essential Nonessential .1 + Position X

QW-405 .2 φ Position X Positions .3 φ ↑↓ Vertical Welding X .1 ± Trail or φ Composition X .2 φ Single, Mixture, or % X .3 φ Flow Rate X .5 ± or φ Backing Flow X

QW-408 .9 - Backing or φ Composition X Gas .10 φ Shielding or Trailing X

2-87 Module 2 – Welding and Cutting Processes Gas Tungsten Arc Welding ASME Section IX – GTAW Process Procedure Variables

Supplementary Paragraph Brief of Variables Essential Essential Nonessential .1 > Heat Input X .3 ± Pulsing I X .4 φ Current or Polarity X X QW-409 Electrical .8 φ I & E Range X Characteristic .12 φ Tugsten Electrode X φ Orifice, Cup, or Nozzle .3 Size X .5 φ Method of Cleaning X φ Single to Multi .10 Electrodes X X .11 φ Closed to Out Chamber X

QW-410 .15 φ Electrode Spacing X Technique .25 φ Manual to Automatic X

2-88 Plasma Arc Welding (PAW)

Module 2A.4 Module 2 – Welding and Cutting Processes Plasma Arc Welding Plasma Arc Welding (PAW) Definition

ƒ Nonconsumable electrode ƒ Heat is produced from a plasma jet z Arc can be transferred or nontransferred ƒ Shielding is obtained from the ionized gas z Usually supplemented by an auxiliary source of shielding gas ƒ Filler metal may of may not be used ƒ Pressure is not used ƒ Variables z Plasma current z Orifice diameter and shape z Type of orifice gas z Flow rate of orifice gas z Type of shielding gas

2-90 Module 2 – Welding and Cutting Processes Plasma Arc Welding Plasma Arc Torch

Source: AWS Handbook 9th ed. Vol. 1 2-91 Module 2 – Welding and Cutting Processes Plasma Arc Welding Why Arc Constriction?

ƒ Columnar shaped plasma jet z Significantly reduces sensitivity to variations in arc length z More stable plasma jet z Permits the use of longer arc lengths z Less welder skill is required (compared to GTAW) ƒ Higher energy density z Increased penetration and travel speeds

Courtesy of the AWS Welding Handbook, Volume 2, 8th Edition 2-92 Module 2 – Welding and Cutting Processes Plasma Arc Welding Transferred and Nontransferred Plasma Arc Modes

CONSTRICTING NOZZLE

ORIFICE GAS

SHIELDING GAS

WORK

TRANSFERRED NONTRANSFERRED

Courtesy of the AWS Welding Handbook, Volume 2, 8th Edition 2-93 Module 2 – Welding and Cutting Processes Plasma Arc Welding Consumables

ƒ Techniques for adding filler metal z Cold wire feed Š Filler wire is introduced at the leading edge of the weld pool Š May be done manually or by conventional GTAW wirefeeders z Hot wire feed Š Wirefeeder introduces wire at the trailing edge of the weld pool z Dabber technique Š Filler wire feed is pulsed in synchronization with the pulsing of the plasma arc current ƒ AWS specifications for consumables used for PAW are the same as those used for GTAW z Filler wires, electrodes, and shielding gases

2-94 Module 2 – Welding and Cutting Processes Plasma Arc Welding Advantages and Disadvantages

ƒ Advantages z Columnar plasma jet Š Higher energy density enables faster welding speeds, lower heat input, and less distortion Š Improved arc stability and tolerance to variations in torch-to-work distance Š Permits the use of longer torch-to-work distances Š Less welder skill is reqq(puired (compared to GTAW ) ƒ Disadvantages z Higher equipment cost z Lower tolerance to variations in fit-up z Manual PAW torches are more difficult to manipulate than manual GTAW torches

2-95 Module 2 – Welding and Cutting Processes Plasma Arc Welding Applications

ƒ Process techniques z Keyhole mode z Melt-in mode ƒ Applicable to all metals weldable by the GTAW process z All metals except aluminum and magnesium are welded with DCEN ƒ Apppplications z Build-ups for aerospace components z Medical pacemakers z Electronic components z Bellows and seals z Motors and transformers z Tube mills z Cladding, wire mesh, process piping

2-96 Module 2 – Welding and Cutting Processes Plasma Arc Welding ASME Section IX – PAW Process Procedure Variables

Supplementary Paragraph Brief of Variables Essential Essential Nonessential .3 φ Size X .4 φ F-Number X .5 φ A-Number X .12 φ Classification X .14 ± Filler X .22 ± Consumable Insert X .23 φ Filler Metal Product Form X .27 φ Alloy Elements X QW-404 Filler .30 φ t X Metals .33 φ Classification X

2-97 Module 2 – Welding and Cutting Processes Plasma Arc Welding ASME Section IX – PAW Process Procedure Variables

Supplementary Paragraph Brief of Variables Essential Essential Nonessential .1 + Position X

QW-405 .2 φ Position X Positions .3 φ ↑↓ Vertical Welding X .1 ± Trail or φ Composition X .4 φ Composition X .5 ± or φ Backing Flow X .9 - Backing or φ Composition X

QW-408 .10 φ Shielding or Trailing X Gas .21 φ Flow Rate X

2-98 Module 2 – Welding and Cutting Processes Plasma Arc Welding ASME Section IX – PAW Process Procedure Variables

Supplementary Paragraph Brief of Variables Essential Essential Nonessential .1 > Heat Input X .4 φ Current or Polarity X X QW-409 Electrical .8 φ I & E Range X Characteristics .12 φ Tugsten Electrode X φ Orifice, Cup, or Nozzle .3 Size X .5 φ Method of Cleaning X φ Single to Multi .10 Electrodes X X .11 φ Closed to Out Chamber X

QW-410 .12 φ Melt-in to Keyhole X Technique .15 φ Electrode Spacing X

2-99 Submerged Arc Welding (SAW)

Module 2A.5 Module 2 – Welding and Cutting Processes Submerged Arc Welding SAW Definition

ƒ At least one consumable bare metal electrode ƒ Arc(s) produce heat ƒ Shielded by granular, fusible material on workpieces ƒ Used without the application of pressure

2-101 Module 2 – Welding and Cutting Processes Submerged Arc Welding SAW Components

Source: AWS Handbook 9th ed. Vol. 1 2-102 Module 2 – Welding and Cutting Processes Submerged Arc Welding SAW Definitions and Variables

Definitions Variables Machine Welding amperage Automatic Welding voltage Semiautomatic Travel speed Tandem arc Electrode size Flux Electrode extension Flux recovery units Width and depth of flux Tractors Manipulators Positioners

2-103 Module 2 – Welding and Cutting Processes Submerged Arc Welding Consumables for SAW

ƒ AWS A5.17, Specification for Carbon Steel Electrodes and Fluxes for Submerged Arc Welding z F7A6-EM12K - 70,000 psi UTS, Charpy toughness of 20 ft-lb @ -60F, with EM12K Medium Mn, 0.12%C, Killed Š F - Flux Š 7 - Tensile Strength in 10,000 psi Š A - Condition of heat treatment Š 6 - Lowest temperature (x -10°C) with Charpy toughness of 20ft-lb Š E - Solid electrode, EC - cored electrode Š M - Classification of manganese content Š L - Low, M - Medium, H - High Š 12 - Carbon content in hundredths of a percent Š K - Killed

2-104 Module 2 – Welding and Cutting Processes Submerged Arc Welding Selection and Application Criteria for SAW

ƒ Advantages z Superior weld quality z Often self cleaning z High deposition rates z Minimum edge preparation z No radiant energy z Minimum fume problem ƒ Disadvantages z Flux housekeeping z Usable only in flat position

2-105 Module 2 – Welding and Cutting Processes Submerged Arc Welding Effect of Amperage Variation on Weld Bead Shape and Penetration

Semiautomatic welding Machine welding 3/32 in. wire, 35V, 24in./s 7/32 in. wire, 34V, 30in./s

350 500 650 700 1000 850 A A A A A A

Welding Processes -- Arc and Gas Welding and Cutting, Brazing and Soldering, AWS Welding Handbook, 7th Ed, Vol. 2, p. 203, fig. 6.5.

2-106 Module 2 – Welding and Cutting Processes Submerged Arc Welding Effect of Arc Voltage Variations on Weld Bead Shape and Penetration

Semiautomatic welding Machine welding 3/32 in. wire, 500A, 24in./s 7/32 in. wire, 850A, 30in./s

27V 45V 34V 25V 35V 45V

Welding Processes -- Arc and Gas Welding and Cutting, Brazing and Soldering, AWS Welding Handbook, 7th Ed, Vol. 2, p. 203, fig. 6.6.

2-107 Module 2 – Welding and Cutting Processes Submerged Arc Welding Effect of Travel Speed Variation on Weld Bead Shape and Penetration

Semiautomatic welding Machine welding 3/32 in. wire, 500A, 35V 7/32 in. wire, 850A, 34V

12 24 48 60 15 30 in./min in./min in./min in./min in./min in./min

Welding Processes -- Arc and Gas Welding and Cutting, Brazing and Soldering, AWS Welding Handbook, 7th Ed, Vol. 2, p. 204, fig. 6.7.

2-108 Module 2 – Welding and Cutting Processes Submerged Arc Welding Effect of Electrode Size on Weld Bead Shape and Penetration

Machine welding 600A, 30V， 30in./min

Electrode size 1/8in. 5/32in. 7/32in.

Welding Processes -- Arc and Gas Welding and Cutting, Brazing and Soldering, AWS Welding Handbook, 7th Ed, Vol. 2, p. 205, fig. 6.8.

2-109 Module 2 – Welding and Cutting Processes Submerged Arc Welding Effect of Work Inclination on Weld Bead Shape in 13-mm (1/2 in.) Plate

Flat position weld Downhill weld (1/8 slope)

Uphill weld (1/8 slope) Lateral weld (1/19 slope)

Welding Processes -- Arc and Gas Welding and Cutting, Brazing and Soldering, AWS Welding Handbook, 7th Ed, Vol. 2, p. 215, fig. 6.12.

2-110 Module 2 – Welding and Cutting Processes Submerged Arc Welding ASME Section IX – SAW Process Procedure Variables

Supplementary Paragraph Brief of Variables Essential Essential Nonessential .4 φ F-Number X .5 φ A-Number X .6 φ Diameter X .9 φ Flux/Wire Classification X .10 φ Alloy Flux X .24 ± or φ Supplemental X .27 φ Alloy Elements X .29 φ Flux Designation X .30 φ t X .33 φ Classification X .34 φ Flux Type X QW-404 Filler .35 φ Flux/Wire Classification X X Metals .36 Recrushed Slag X

2-111 Module 2 – Welding and Cutting Processes Submerged Arc Welding ASME Section IX – SAW Process Procedure Variables

Supplementary Paragraph Brief of Variables Essential Essential Nonessential QW-405 Positions .1 + Position X .1 > Heat Input X QW-409 Electrical .4 φ Current or Polarity X X Characteristics .8 φ I & E Range X .5 φ Method of Cleaning X .8 φ Tube-Work Distance X φ Single to Multi .10 Electrodes X X

QW-410 .15 φ Electrode Spacing X Technique .25 φ Manual or Automatic X

2-112 Gas Metal Arc Welding and Flux Cored Arc Welding (GMAW & FCAW)

Module 2A.6 Module 2 – Welding and Cutting Processes Gas Metal and Flux Cored Arc Welding Gas Metal Arc Welding

Source: AWS Handbook 9th ed. Vol. 1 2-114 Module 2 – Welding and Cutting Processes Gas Metal and Flux Cored Arc Welding Flux Cored Arc Welding

Self-Shielded FCAW Gas-Shielded FCAW

Courtesy of the AWS Welding Handbook, Volume 2, 8th Edition

2-115 Module 2 – Welding and Cutting Processes Gas Metal and Flux Cored Arc Welding GMAW/FCAW Equipment

SHIELDING GAS REGULATOR

ELECTRODE SUPPLY 7

ELECTRODE FEED UNIT SHIELDING GAS SUPPLY

3 2 5 4 8 POWER 6 SOURCE 9 WELDING GUN WATER CIRCULATOR 1 10 WORKPIECE

1 WORK LEAD 6 CABLE ASSEMBLY 2 WATER TO GUN 7 SHIELDING GAS FROM CYLINDER 3 WATER FROM GUN 8 WELDING CONTACTOR CONTROL 4 GUN SWITCH CIRCUIT 9 POWER CABLE 5 SHIELDING GAS TO GUN 10 PRIMARY INPUT POWER

Courtesy of the AWS Welding Handbook, Volume 2, 8th Edition 2-116 Module 2 – Welding and Cutting Processes Gas Metal and Flux Cored Arc Welding Consumables for GMAW

ƒ Primary consumables are the wire and the shielding gas ƒ A5.18 Specification for Carbon Steel Electrodes and Rods for Gas Shielded Arc Welding ƒ C5.10 Recommended Practices for Shielding Gases for Arc Welding and Plasma Cutting ƒ ERxxS-y z ER – Electrode or rod z xx - Two or three digits for tensile strength in KSI z S - Solid wire z y - Suffix for specifying chemistry and other details

2-117 Module 2 – Welding and Cutting Processes Gas Metal and Flux Cored Arc Welding Consumables for FCAW

ƒ A5.20 Specification for Carbon Steel Electrodes for Flux Cored Arc Welding ƒ C5.10 Recommended Practices for Shielding Gases for Arc Welding and Plasma Cutting ƒ ExyT-ab z E - Electrode z x – One or two digits for tensile strength in 10’s of KSI z y - Welding position (0 = flat or horizontal, 1 – all) z T - Tubular z a - Usability, performance

2-118 Module 2 – Welding and Cutting Processes Gas Metal and Flux Cored Arc Welding GMAW/FCAW Variables

ƒ Wire feed speed (WFS) z Controls the welding current ƒ Arc voltage ƒ Polarity ƒ Travel speed ƒ Electrode extension ƒ Torch angles z Work and travel angles ƒ Joint design ƒ Electrode diameter ƒ Shielding gas

2-119 Module 2 – Welding and Cutting Processes Gas Metal and Flux Cored Arc Welding WFS, Voltage, and CTWD

ƒ WFS z Primary variable that controls heating and melting power to the electrode z Increasing the WFS increases the deposition rate and weld penetration ƒ Voltage z Impact s th e melti ng e ffic iency a t the wor kp iece an d the we ld s hape z Improper voltage can result in arc instabilities and inadequate welds ƒ Contact Tip to Word Distance (CTWD) z Longer CTWDs result in greater preheating in the electrode stick-out, lower heat input into the workpiece, and a more crowned weld bead Š Secondary affect on heat input to the workpiece compared to current, voltage, and travel speed

2-120 Module 2 – Welding and Cutting Processes Gas Metal and Flux Cored Arc Welding Modes of Metal Transfer

Spray Globular

Short-circuiting Pulse-spray

2-121 Module 2 – Welding and Cutting Processes Gas Metal and Flux Cored Arc Welding GMAW (transfer mode)

Globular mode Spray mode

TlditiTravel direction

WFS=200 IPM, 29V, T=10 IPM

ER70S-3, 0.052” welding wire was used

Ar-10%CO2 shielding gas was used Stainless Wire ER308L

Recording rate 125 Hz for globular and spray modes

2-122 Module 2 – Welding and Cutting Processes Gas Metal and Flux Cored Arc Welding FCAW

WFS= 225 IPM, V= 29V , T= 10 IPM

0.045” welding wire was used Ar-10%CO2 shielding gas was used Recording rate was 1125 Hz

2-123 Module 2 – Welding and Cutting Processes Gas Metal and Flux Cored Arc Welding Short Circuit Transfer

Wire shorts to Arc reignites plate Metal transfer

2-124 Module 2 – Welding and Cutting Processes Gas Metal and Flux Cored Arc Welding Globular Transfer

Drop short circuits and explodes producing spatter

Irregular droplet size Random transfer

2-125 Module 2 – Welding and Cutting Processes Gas Metal and Flux Cored Arc Welding Spray Transfer

2-126 Module 2 – Welding and Cutting Processes Gas Metal and Flux Cored Arc Welding Pulse Spray Transfer

ƒ Synergic control: in modern supplies, pulse waveforms are automatically adjusted to accommodate a wire feed rate set by the user

2-127 Module 2 – Welding and Cutting Processes Gas Metal and Flux Cored Arc Welding GMAW (transfer mode)

Pulsed mode

2-128 Module 2 – Welding and Cutting Processes Gas Metal and Flux Cored Arc Welding Typical Weld Cycle

Electrode contacts workpiece (short circuit current)

Start current Welding current

Crater fill current Open circuit voltage Welding wire feed speed Start wire feed speed Burnback voltage eed, and travel speed pp Crater fill wire feed Welding voltage speed Run-in Start voltage wire feed speed

Travel speed

Current, voltage, wire feed s Crater fill voltage

Preflow Run-in Start Weld Crater fill Burnback Postflow time time time time time time time

Welding cycle time

2-129 Module 2 – Welding and Cutting Processes Gas Metal Arc Welding Advancements Reciprocating Wire Feed GMAW

2-130 Module 2 – Welding and Cutting Processes Gas Metal and Flux Cored Arc Welding Selection and Application Criteria for GMAW

ƒ Advantages z Welds all commercial metals z All positions z High deposition rates compared to GTAW and SMAW Š Continuously fed filler wire z Long welds without stops and starts z Min ima l pos t-weld an d in ter-pass clileaning ƒ Limitations z Welding equipment is more complex than that for SMAW Š More difficult to use in hard to reach places Š Welding torch size z Welding torch must be kept in close proximity to the workpieces in order to achieve adequate shielding z Arc must be protected against air drafts

2-131 Module 2 – Welding and Cutting Processes Gas Metal and Flux Cored Arc Welding Selection and Application Criteria for FCAW

ƒ Advantages z High deposition rates z Deeper penetration than SMAW z High quality welds z Less pre-cleaning than GMAW z Slag covering helps with out-of-position welds z Self-shielded FCAW is draft tolerant ƒ Disadvantages z Slag must be removed z Higher fume generation than GMAW and SAW z Spatter z Equipment is more expensive and complex than SMAW z FCAW wire is more expensive

2-132 Module 2 – Welding and Cutting Processes Gas Metal and Flux Cored Arc Welding ASME Section IX – GMAW & FCAW Process Procedure Variables

Supplementary Paragraph Brief of Variables Essential Essential Nonessential .4 φ F-Number X .5 φ A-Number X .6 φ Diameter X .12 φ Classification X .23 φ Filler Metal Product Form X .24 ± or φ Supplemental X .27 φ Alloy Elements X .30 φ t X QW-404 Filler .32 t Limits (S.Cir. Arc) X Metals .33 φ Classification X

2-133 Module 2 – Welding and Cutting Processes Gas Metal and Flux Cored Arc Welding ASME Section IX – GMAW & FCAW Process Procedure Variables

Supplementary Paragraph Brief of Variables Essential Essential Nonessential .1 + Position X

QW-405 .2 φ Position X Positions .3 φ ↑↓ Vertical Welding X .1 ± Trail or φ Composition X .2 φ Single, Mixture, or % X .3 φ Flow Rate X .5 ± or φ Backing Flow X

QW-408 .9 - Backing or φ Composition X Gas .10 φ Shielding or Trailing X

2-134 Module 2 – Welding and Cutting Processes Gas Metal and Flux Cored Arc Welding ASME Section IX – GMAW & FCAW Process Procedure Variables

Supplementary Paragraph Brief of Variables Essential Essential Nonessential .1 > Heat Input X .2 φ Transfer Mode X QW-409 Electrical .4 φ Current or Polarity X X Characteristics .8 φ I & E Range X φ Orifice, Cup, or Nozzle .3 Size X .5 φ Method of Cleaning X .8 φ Tube-Work Distance X .10 φ Single to Multi Electrodes X X

QW-410 .15 φ Electrode Spacing X Technique .25 φ Manual or Automatic X

2-135 Other Arc Welding Processes

Module 2A.7 Module 2 – Welding and Cutting Processes Electroslag Welding Electroslag Welding (ESW) Definition

ƒ Pieces welded by molten slag that melts the filler metal and the surfaces of the workpieces to be welded ƒ ESW is not a “true” arc process

Source: AWS Handbook 9th ed. Vol. 1 2-137 Module 2 – Welding and Cutting Processes Electroslag Welding Advantages of ESW

ƒ Deposition rates of 35- to 45-lbs/hr ƒ Sections with thicknesses ≥ ¾-in ƒ Preheating and post-heating are normally not required ƒ Long molten time allows gas and slag to escape ƒ High duty cycle with little operator fatigue ƒ Min imum ma ter ia l han dling ƒ Minimum distortion ƒ No spatter z 100% of filler metal is transferred to the weld ƒ Fastest welding process for large, thick materials

2-138 Module 2 – Welding and Cutting Processes Electroslag Welding Limitations of ESW

ƒ Limited to carbon, low alloy, and some stainless steels ƒ Only applicable to vertically positioned joints ƒ Single pass welding only z Process cannot be interrupted, or else weld will contain discontinuities and flaws ƒ Minimum base metal thickness of approximatel y ¾-in ƒ Complex material shapes may be difficult or impossible to weld

2-139 Module 2 – Welding and Cutting Processes Electroslag Welding Application of ESW

ƒ Used for welding carbon, low alloy, and some stainless steels in a single pass ƒ Recognized by all of the important national codes z Several have requirements that differ from other welding processes ƒ Widely used for structural applications z Transition jjgoint between different flange thicknesses z Stiffeners in box columns and wide flanges ƒ Large presses and machinery with large, heavy plate ƒ Pressure vessels

2-140 Module 2 – Welding and Cutting Processes Electroslag Welding Safety and Health of ESW

ƒ Refer to Z49.1 of AWS and OSHA Title 29 Part 1910 for details ƒ Safety glasses with side shields are recommended ƒ Electrical safety due to all parts of operation being electrically "HOT" ƒ Stay away from fumes ƒ Slag leakage may be a problem ƒ Be cautious with hot shoes, sumps, and run-off blocks

2-141 Module 2 – Welding and Cutting Processes Electroslag Welding ASME Section IX – ESW Process Procedure Variables

Supplementary Paragraph Brief of Variables Essential Essential Nonessential .4 φ F-Number X .5 φ A-Number X .6 φ Diameter X .12 φ Classification X .17 φ Flux Type or Composition X .18 φ Wire to Plate X QW-404 Filler .19 φ Consumable Guide X Metals .33 φ Classification X QW-409 Electrical Characteristics .5 φ ± 15% I & E Range X .5 φ Method of Cleaning X

QW-410 .10 φ Single to Multi Electrodes X X Technique .15 φ Electrode Spacing X

2-142 Module 2 – Welding and Cutting Processes Electrogas Welding Electrogas Welding (EGW) Definition

ƒ Arc welding process that uses an arc between a continuous filler metal electrode and the weld pool ƒ Employs vertical position welding with backing to confine the molten weld pool ƒ Externally applied shielding gas may or may not be used z No granular flux

Courtesy of the AWS Welding Handbook, Volume 2, 9th Ed. 2-143 Module 2 – Welding and Cutting Processes Electrogas Welding Application of EGW

ƒ Storage tanks, ship hulls, structural members, and pressure vessels z High heat input gives large grain size z Used for 3/8- to 4-in. thicknesses z Reduced need for preheat z Reduced need for PWHT z Reduced distortion ƒ Problem may be low notch toughness ƒ High voltages are needed to melt into sidewalls

2-144 Module 2 – Welding and Cutting Processes Electrogas Welding ASME Section IX – EGW Process Procedure Variables

Supplementary Paragraph Brief of Variables Essential Essential Nonessential .4 φ F-Number X .5 φ A-Number X .6 φ Diameter X .12 φ Classification X QW-404 Filler .23 φ Filler Metal Product Form X Metals .33 φ Classification X

QW-408 .2 φ Single, Mixture, or % X Gas .4 φ Flow Rate X

2-145 Module 2 – Welding and Cutting Processes Electrogas Welding ASME Section IX – EGW Process Procedure Variables

Supplementary Paragraph Brief of Variables Essential Essential Nonessential .1 > Heat Input X QW-409 Electrical .4 φ Current or Polarity X X Characteristics .8 φ I & E Range X .5 φ Method of Cleaning X .8 φ Tube-Work Distance X φ Single to Multi QW-410 .10 Electrodes X X Technique .15 φ Electrode Spacing X

2-146 Module 2 – Welding and Cutting Processes Arc Stud Welding Arc Stud Welding Definition

ƒ Attachment of threaded studs to base plate ƒ Local melting at interface by ~0.1-2 second arc ƒ Metal expulsion during plunging ƒ Capacitor discharge is a less common process for stud welding

Source: AWS Handbook 9th ed. Vol. 1

2-147 Module 2 – Welding and Cutting Processes Arc Stud Welding ASME Section IX – Arc Stud Process Procedure Variables

Supplementary Paragraph Brief of Variables Essential Essential Nonessential

QW-402 .8 φ Stud Shape Size X Joints .9 - Flux or Ferrule X QW-405 Positions .1 + Position X QW-408 Gas .2 φ Single, Mixture, or % X .4 φ Current or Polarity X .8 φ I & E Range X .9 φ Arc Timing X QW-409 Electrical .10 φ Amperage X Characteristics .11 φ Power Source X QW-410 Technique .22 φ Gun Model or Lift X

2-148