Arc Welding Reading

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HOT METAL SKILLS

8609-D

ARC WELDING – WELD JOINTS, OUT–OF–POSITION WELDING,AND OTHER USES OF THE ARC WELDER

INTRODUCTION

Arc welding is a skill and a craft that takes place in a variety of places. Welding can be done just aboutanywhere on earth; it can even be done underwater. Therefore, it is necessary to learn to perform qualitywelds in a large variety of environments and positions. The American Welding Society (AWS) has a given setof codes to describe the different types of welds, welding positions, quality factors, and when a particularweld should be used. It is important to become familiar with the types of welds, weld joints used, and somealternative uses of the arc welder in order to become skilled in the craft.

TYPES OF WELDS

There are two main types of welds made today. It is possible to identify the majority of welds made today bydescribing them as either a “groove”* or “fillet” weld. A groove weld is produced when the sides or ends oftwo pieces are put together. The shape of the edges that are joined together during the welding processdetermines the proper name for a groove weld. The following is a set of illustrations that describe somecommon types of groove welds.

* Underlined words are defined in the Glossary of Terms.

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A fillet weld is produced when metal is placed together to form a right angle. The fillet name actually de-scribes the triangle of metal that is formed by the weld in this situation. Fillet welds are very prominent in theindustry and understanding the nomenclature of welding is a key to becoming successful in the craft.

TYPES OF WELD JOINTS

A weld joint is the junction of two pieces of metal. This is the location at which two or more pieces of metalare to be joined. There are five common types of weld joints used today. These are:

Butt Joint – this is a type of joint made between two pieces of metal lying in the same plane.Tee Joint – a joint that is made when two pieces of metal are placed together to form a “T.”Lap Joint – joint made when two pieces of metal overlap one another.Corner Joint – this is a joint made when two pieces of metal are placed at right angles to each otherto make a 90–degree angle.Edge Joint – a joint that is formed by placing two pieces of metal parallel to one another or bystacking one on top of the other.

AWS CODES

It is important to become knowledgeable about every type of welding position in use today for makinggroove and fillet welds on metal plate and pipe. As mentioned earlier, the American Welding Society (AWS)has developed a system to simplify this process. The system is very easy to understand. If a “G” appearsbefore each position this indicates that the weld being described is a groove weld. Conversely, if an “F”appears it indicates that the weld in question is a fillet weld.

The system has been set up to also describe the type of welding position that is being used. In order to dothis the AWS uses four digits. The numbers one through four are used to identify the types of weldingpositions possible. A “1” indicates that the weld was made in the flat position, a “2” indicates the horizontalposition, a “3” the vertical position, and a “4” the overhead position. In addition to these four digits, a fiveand six are used to describe two types of welds used when working with pipe. The five indicates a horizontalfixed pipe position and the six indicates an inclined fixed pipe position. Some examples of weld names are:

1G – groove weld, in the flat position 5G – groove weld on pipe, in the horizontal fixed position2G – groove weld, in the horizontal position 6G – groove weld on pipe, in the inclined fixed position3G – groove weld, in the overhead position 1F – fillet weld, in the flat position4G – groove weld, in the overhead position 3F – fillet weld, in the vertical position

Common Weld Joints

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The following is an illustration that adequately shows the AWS system at work.

Weld Testing Positions

Grove Weld Positions

In most instances it will be necessary to make more than one weld pass to properly secure a joint. There area few terms that are given to the types of weld passes needed to adequately join two pieces of metal. Manytimes, the first weld pass will be referred to as the stringer, or root pass, and requires full penetration of themetal being welded. The second pass is referred to as a hot pass, the third is called a filler pass and the finalpass is called a cap or cover pass. Keep in mind that not all weld joints will require all four weld passes tobe run. Each pass is meant to cover the previous one and join a bit more of the metal to the welds.

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PROCEDURE FOR MAKING BUTT WELDS

A good place to start when learning how to perform butt welds on metal plate is in the flat position (1G). Thisis the most basic type of weld performed today. The following is one practice method for performing a buttweld in the flat position (1G):

Use a welding machine that has been properly set up and adjusted, a 1/8-inch diameter electrode andtwo or more pieces of steel plate at least 1/2 or 3/4 inch thick. Practice with this size of metal becauseit coincides with the requirements of the Entry-Level Weldor Test.

Tack weld the two plates together at the ends. Tacking will prevent the metal from warping during thewelding process.

Begin on either end of the metal by establishing a molten weld pool on both plates. Keep the elec-trode in the molten weld pool until it flows together or for a count of three seconds.

After the pool is well established, begin weaving the electrode slowly back and forth across the joint.Use any of the electrode movements that were discussed earlier.

Continue along the length of the joint. After weld completion, cool, chip, and inspect the weld.

Several passes will be needed to adequately construct a butt joint. Commonly, all four passesare used.

Practice this type of weld repeatedly until possessing mastery of the weld.

In most instances, full penetration is not required for this type of weld. In cases that call for full penetration,the plates should be beveled on the joint edge and the same procedure used. There are many types ofpractice methods used to complete butt welds. Acquire the knowledge needed to master butt welds in the1G, 2G, 3G, 4G, 5G, and 6G positions. Repeated practice is key to becoming proficient at each of thesewelds. Become familiar with the types of weld tests that will be completed to determine the strength andquality of the welds you produce. Two common tests used by the American Welding Society (AWS) are the

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X-ray and Guided Bend tests. Some excellent learning tools are available from the Instructional MaterialsService (IMS). IMS offers two instructional videos that provide excellent instruction in Shielded Metal ArcWelding. These are: Video # 9989 Weld Test Coupon Preparation: Plate and Pipe, and Video # 9990Performing the SMAW 2G, 3G, and 4G Weld Test: Plate/E-6010.

PROCEDURE FOR MAKING FILLET WELDS

The other common weld produced is the fillet weld. Much like the groove weld, there are many practicetechniques that can be put to use to allow a person to master fillet welding. The following is one set ofinstructions for making a fillet weld on a tee joint in the flat position (1F).

Use a welding machine that has been properly set up and adjusted, a 1/8-inch diameter electrode andtwo or more pieces of steel plate at least 1/4 inch thick.

Tack weld the pieces together to form a right angle or a “T.” Be certain to chip the tack weld toremove any slag. If the slag is not removed, the final weld will be faulty.

A welded tee joint should be welded on both sides to increase the strength of the tee joint.

After the tack weld has been tacked and chipped, start at either end of the plate and establish amolten pool on both plates or hold for a count of three seconds.

Use any of the electrode movements that have been discussed. It is suggested that you find a move-ment that works best for you and continue to use it.

Often three passes will be needed to complete this type of joint. A root pass will be needed, as wellas a filler and cap pass.

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When welding thin metal to heavy metal, the angle of the electrode should be about 60° towards theheavier metal.

One tip to bear in mind, fillet welding can be made much easier by placing the “T” joint in the “V” position.After tacking the two metal plates together, maneuver the two pieces to form a “V” shape. This allows for aflat type of weld, increased travel speed, and reduced undercutting. The arc should remain short and it iscritical that the electrode be held in the center of the “V” to ensure that both plates are being joined equally.In some instances, more than one weld pass will be needed. In these cases, it is possible to practice weavepatterns in the “V” during each pass.

HORIZONTAL, VERTICAL, AND OVERHEAD POSITION WELDING

After you become skilled at welding in the flat position, it is necessary to begin welding in the three moredifficult positions. The horizontal (2), vertical (3), and overhead (4) positions are referred to as out-of-position welds, and are all challenging because it is harder to control the weld puddle. In all three of thesepositions, it becomes very difficult to control the molten metal in the puddle and keep it from falling from theweld area. Some general practices in out-of-position welding are as follows:

Experiment with several amperage settings to determine which is best for horizontal, vertical, andoverhead welding. Whenever possible, use the highest amperage possible for quality work andbetter weld penetration. In most cases, lower amperage will be needed for this type of work ascompared to welding in the flat position.

Place the electrode in the proper position.

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Strike the arc and hold a shorter arc than is required for flat position welding.

After an arc is established, begin moving the electrode very slowly, bringing the metal to a moltenstate. Continue this until the molten metal will no longer remain in the weld puddle. Increase travelspeed until the desired weld buildup is obtained. Travel speed is critical to these types of welds. Ifa correct travel speed is used, the molten metal will solidify before dropping or sliding off.

Use the proper size and type of electrode. (AWS) No. E6011 is one type of electrode that is suitedfor out-of-position welding. Consult an electrode classification chart to determine which electrodesare suitable for this type of work. One bit of information to keep in mind. Electrodes of smallerdiameter are usually easier to control than larger diameter electrodes.

Cool, chip, and inspect the welds for any defects as well as checking for uniformity.

Vertical Welding

There are two basic techniques for performing welds in the vertical position. These two techniques arecommonly referred to as “vertical up” and “vertical down.” These two techniques can be used to performwelds in the 3G and 3F positions. The following is a set of instructions for performing “vertical up” and“vertical down” welds.

For most weldors, light metal is easier to weld than heavy metal because it requires less penetration.For the practice sessions, use a thin metal, usually 1/8 inch. This will allow for a weldor to practiceeasier and get the “feel” of these more difficult welding positions. It is recommended that you use anelectrode that is approximately eight inches long and that you begin by setting the amperage at 75.

Be certain that the metal plate is secured in a vertical position. The use of adjustable locking pliers orC-clamps is recommended to aid in securing the metal in position.

Position the electrode at an angle of 60º to the plate and in the path of the weld. The electrode shouldbe perpendicular to the sides of the plate.

For “vertical down” welding, begin at the top of the plate with a short arc. If the electrodesticks, stop and increase the amperage. If the electrode burns through the metal, lower theamperage. If the electrode continues to burn through the metal, increase the speed of the elec-trode movement downward.

Vertical Down Welding

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When welding “vertical up”, position the electrode 85º to the plate in the path of the weld. Begin atthe bottom of the plate and work up. Use the same procedures if the electrode sticks or burnsthrough the metal.

As you become better at welding in the 3G and 3F positions, begin work on thicker metals. Experi-ment and increase the amperage accordingly. When welding thick plate, use one or more side-to-side electrode movements.

As with fillet welds, “vertical up” and “vertical down” welds will need more than one pass. A rootpass should be made, along with a filler and cap pass.

Horizontal Welding

When welding in the 2G or 2F position it is necessary to control the weld puddle and travel speed to producea strong weld. The horizontal position is used widely in agricultural sectors to make repairs. The stepsnecessary to perform welds in the 2G or 2F position are:

Secure the plate in a position for running beads in a straight line from left to right. Use adjustablelocking piers or C-clamps to secure the metal firmly.

When performing this type of weld, the electrode and the plate sides should form a 90º angle. Leanthe electrode slightly in the direction of the weld area.

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Adjust the amperage, travel speed, and arc length to prevent the weld puddle from running or sagging.

Metal that is over 1/8 inch thick should be beveled prior to welding in the horizontal position. Ifwelding thicker metal, or metal that has been beveled, it is necessary to make more than one weldpass to enhance the strength of the weld.

A root, filler, and cap pass will be necessary.

Overhead Welding

Welding in the 4G or 4F position is the most difficult of the out-of-position welds. The major challenge in thistype of welding is controlling the weld puddle. The procedures for performing overhead welds are verysimilar to the flat position, except that they are far more difficult. It is necessary to pay special attention to theweld puddle and travel speed. You must maintain a short arc as well. The steps in overhead welding are:

Secure the metal overhead with the use of an adjustable locking pliers or C-clamps.

Find a position that is comfortable for you before starting to weld. Welding in the 4G or 4F positionis much more difficult if the weldor is uncomfortable from the start.

Adjust the amperage setting and travel speed. The amperage should be set at approximately thesame setting as needed during vertical welding (3). Be certain to maintain a very short arc lengththroughout the entire process.

Weld with a short arc and use a moderately fast rate of travel to prevent sagging and undercutting.

Overhead Welding

A weaving pattern is recommended for use on heavier metals. This motion must be faster thanweaves used for other position welds.

Three passes will be needed to complete this weld properly.

Be aware of the danger of falling molten metal when welding in the 4G or 4F position. Personal protectiveequipment (PPE) should always be worn and becomes even more important when performing these typesof welds.

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WELDING VARIOUS KINDS OF METALS

Arc welding requires knowledge of the many metals that are being welded. As mentioned earlier, metalshave a variety of different properties and characteristics. It is necessary to be familiar with the many types ofmetals and which types of electrodes and techniques can be used to weld them. The following is a list ofdifferent kinds of metals that require some knowledge and expertise to weld.

Cast Iron

Cast iron is more difficult to weld than other types of metals. This form of metal expands, contracts, andeven crumbles under certain heating conditions. One important point to remember about cast iron, it can bedamaged by both the heating and cooling processes. During the cooling phase, cracks may appear in or nearthe welded area. Consult an electrode identification chart to ensure the electrode used is correct for themetal that is being welded.

In years past, it was recommended that steel-cored electrodes not be used for welding malleable cast iron.This is no longer the case. Low cost special steel electrodes are used today to weld cast iron and areavailable for purchase from most welding supply stores. These types of electrodes are recommended forrepairing pits and cracks in castings. In cases where these types of electrodes are used you can finish thework with a grinder.

The most commonly used electrode for welding cast iron has a Nickel (Ni) core. These electrodes producea weld that can be sawed, drilled, ground, or machined in just about any way. Nickel-core electrodes aregenerally a bit more expensive than the mild steel variety. Advantages of using a nickel electrode are:

the metals are machinablethe casting does not require preheatingthe cooling speed does not have to be controlled

Sheet Metal

This metal can be described as any thickness of metal that is less than 1/8”. The 1/8” metal is approximately thesame thickness as a 7-gauge metal 0.1793” thick. Due to its thin size, sheet metal is very difficult to weld. Itis very important to weld with the correct amount of heat and use a very short arc. The following stepsshould be followed when welding sheet metal.

Utilize a low amperage setting and weld as rapidly as possible to prevent burning a hole in the metal.Be sure to have adequate heat to allow for complete fusion of the metal.

Select an electrode that is no larger in diameter than the thickness of the metal being welded.

Maintain a very short arc.

In some cases, welders are equipped with special attachments that make it easier to strike an arc when thewelder is set on the very low amperage needed for welding sheet metal.

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High Carbon Steel

Much like cast iron, this type of metal requires some extra precautions to produce high-quality welds. Highcarbon steel is harder, stronger and more brittle than other types of steel. In short, high carbon steel is harderto weld because the effects of heating and cooling are greater. If heated too quickly, the steel can break orhave hard spots. If high carbon steel is cooled too rapidly, the metal becomes brittle. Welding procedure isas follows:

Use mild steel electrodes only if the metal is preheated before and during the weld procedure. Pre-heat the metal to a blue color and maintain this color throughout the weld. If using low-hydrogenelectrodes, it is not always necessary to preheat the metal.

If using a mild steel electrode, set the amperage lower than required for welding mild steel.

Allow the metal and welding area to cool slowly.

CUTTING WITH THE ARC WELDER

Although less common today, there are still instances in the machine shop or agricultural laboratory in which anarc welder will be used to cut metals. Plasma cutters and oxyfuel torches are commonly used, yet there may bea time and place in which this skill will be needed. It is possible to cut, pierce, or gouge metal if the properprocedure is used. When using the arc welder as a cutting machine, more ventilation will be needed becausemore fumes are produced during cutting. Steps to follow in cutting metal with the arc welder include:

Before beginning to cut, remove all flammable materials from the primary and surrounding workareas. Using the welder at high amperage levels can increase the amount of sparks and forces themto travel greater distances than normal.

Select a mild steel (E6011) electrode 1/8” to 3/16” and set the amperage at 160 to 180.

Extend the area to be cut out over the edge of the table and start the cut at the edge of the metal.Place a container of sand underneath the edge of the cut area to catch any molten metal.

Strike and hold a long arc until a large molten puddle forms. After the puddle forms, begin moving theelectrode up and down like a chisel. This shortening of the arc will blow the molten puddle loosefrom the plate. Continue to move across the plate, utilizing a long arc to form the puddle and a shortarc to force the puddle out.

Steps to follow in piercing holes in metalwith the arc welder are:

Strike the arc and hold steady,forming a large molten crater.

As the metal enters a moltenstate, force the electrode down-ward through the plate.

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Cutting bevels can be accomplished with ease using a torch or grinder, but the arc welder can be used in thefollowing manner:

Lean the electrode in the direction of the bevel and strike the arc. Maintaining a long arc, work tokeep the angle between the electrode and the metal the same as the desired finished bevel.

Hold the electrode near the metal and move in the direction of the cut as the metal is blown from itspath of travel. Use a shorter arc for the actual cutting process.

SURFACING OF METALS

It is sometimes necessary to cover the surfaces of tools and machines with metals to increase their strength,size, lifespan, and other properties. There are two major types of surfacing done today. These are:

Hard surfacing – process completed with an arc welder, that gives a hard, tough, cover to metals inorder to resist corrosion, abrasion and impact loads.

Metallizing – spray coating process in which particles of metal are applied to worn metal surfaces.

Special materials are required for use in hard surfacing. Some common materials used for hard surfacingwith the arc welder are: iron, nickel, copper, or cobalt. These types of electrodes are available for use todayand are utilized by applying a layer of wear-resistant metal to the surface or cutting edge of a tool or machinepart. Hard surfacing is commonly used to repair worn edges of agricultural equipment, such as plowshares,cultivator sweeps, bucket teeth, harrow spikes, and planter shovels. Steps for hard surfacing are as follows:

Prepare the metal for surfacing. Clean the metal thoroughly, removing all rust, deposited metal,and paint.

Select the proper electrode by consulting an electrode identification chart. Set the amperage at theminimum level that is needed to strike an arc. (It is critical to set the amperage as low as possible inorder to minimize the dilution of the deposited metal.)

Work in a flat position to insure best results.

Strike the arc and use a medium long arc as you begin to travel with the weld. Use a straight orweaving electrode movement.

Remove all slag before any other layers or beads are run.

Overlap the adjoining welds in order to provide complete fusion. The illustration on the next pagedemonstrates the proper methods for overlapping.

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Continue to run beads next to one another until the surface is covered.

Use a whipping movement when welding along a thin edge.

Peen the deposited metal as it cools.

AWS CERTIFICATION

This certification is available to anyone who possesses a talent for welding. The steps to follow whenattempting to become an Entry-Level Weldor are:

1. Complete and submit an application form.

2. Pass a practical knowledge test. Subjects covered include: welding and cutting theory, welding andcutting inspection and testing, welding and cutting terms and definitions, base and filler metal identifi-cation, base and filler metal selection, common welding process variables, electrical fundamentals,drawing and welding symbol interpretation, fabrication principles and practices, and safety.

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3. A minimum grade of 75 is needed in order to pass with at least 90% of the safety questions beinganswered correctly.

4. Pass performance tests. These tests involve reading and interpreting simple welding drawings andsketches, cutting parts to proper size, fitting sample assemblies, welding in the 2G and 3G positions,workmanship tests using GMAW and FCAW for carbon steel, and GTAW on carbon steel, stainlesssteel and aluminum.

5. If all requirements are met the participant is certified as an Entry-Level Weldor.

The following is a table that illustrates some types of tests used in the industry today.

If you are interested in becoming certified, ask the agricultural science teacher at your school for details andinformation regarding the program.

For arc welding activities related to your SAEP, refer to IMS #RB-221, Activities for Agricultural Science221. After completing an activity, be sure to record the entry in the journal page of your Internet recordbook, and click on 221-H for the Course and Unit of Instruction.

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Acknowledgements

Jared Doughty, Graduate Technician, Department of Agricultural Education,Texas A&M University, revised this topic

Kirk Edney, Curriculum Specialist, Instructional Materials Service,Texas A&M University, reviewed this topic.

Vickie Marriott, Office Software Associate, Instructional Materials Service,Texas A&M University, prepared the layout and design for this topic.

Christine Stetter, Artist, Instructional Materials Service,Texas A&M University, prepared the illustrations for this topic.

REFERENCES

Alexander, R., E. Bohnart, and R. Witcraft. Welding, The Fundamentals of Welding, Cutting, Brazing,Soldering, and Surfacing of Metals. John Deere Publishing. 2000.

Althouse, A., K. Bowditch, W. Bowditch, and C. Turnquist. Modern Welding. The Goodheart-WilcoxCompany, Inc. 1988.

American Welding Society: The AWS Certified Welder Program (Brochure).

Anderson, W., T. Hoerner, and V. J. Morford. Metals and Welding. Hobar Publications. 1988.

AWS QC7-93. Standard for AWS Certified Welders. American Welding Society. 1993.

Jeffus, Larry. Welding: Principles and Applications. 4th Edition. Delmar 1999.

“Joint Design and Preparation of Metals.” [Online] Available: http://www.machinist.org.army_welding/Ch4.htm

Matthews, J. & Sellon, W. Arc Welding: A Basic Manual of Instruction for Learning How to Use ArcWelding. The James F. Lincoln Arc Welding Foundation. Cleveland, OH.

GLOSSARY OF TERMS

Fillet – Type of weld produced when pieces of metal are placed together to form a right angle.Gauge – Measure of thickness of metal.Groove – Type of weld produced when the sides or ends of two pieces of metal are put together.Machinable – Capable of being sawed, drilled, grinded or machined in any way.Malleable – Capable of being fashioned into a different form or shape.Metallizing – Spray coating process in which particles of metal are applied to worn metal surfaces.Tack – Joining two pieces of metal together with a very small, short weld to prevent warping or spreading.

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SELECTED STUDENT ACTIVITIES

SHORT ANSWER/LISTING: Answer the following questions or statements in the space provided or onadditional paper.

1. List and describe the five common types of weld joints.____________________________________________________________________________

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2. Why is it necessary to weld a tee joint on both sides?____________________________________________________________________________

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3. What is the major challenge to overcome when welding in the horizontal, vertical or overhead position?____________________________________________________________________________

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4. List three reasons for surfacing metals.____________________________________________________________________________

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5. Why is it critical to utilize as low of amperage setting as possible when hard surfacing metals?____________________________________________________________________________

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ADVANCED ACTIVITIES

1. Navigate the Internet searching for links that give information regarding the American Welding Society(AWS) welder certification programs. Find out the requirements, costs, and other pertinent informa-tion. Present your findings to the class and encourage them to begin work toward achieving certification.

2. Research the many types of metals and the properties of each. Find information concerning elec-trode identification and formulate your own electrode identification chart. Show the many types ofelectrodes that can be used and the metals that they should be used on and why. Present the chart toyour peers and continue to use it throughout the class.

ALL RIGHTS RESERVED

Reproduction prohibited without written permission.Instructional Materials Service

Texas A&M University2588 TAMUS

College Station, Texas 77843-2588http://www-ims.tamu.edu

2002