SMAW Applications 311
This class provides an overview of how to perform shielded metal arc welding (SMAW), important variables to consider, and how to prevent common defects. It is important to select appropriate electrodes and base metals for SMAW and prepare them for welding. Welders must also choose proper arc starting methods, bead types, and travel speeds and know how to effectively break and re-start the arc when necessary. Common SMAW discontinuities include porosity, undercut, incomplete penetration, excessive penetration, and incomplete fusion.
After taking this class, users will be familiar with many of the considerations and variables that go into performing SMAW. A good understanding of these concepts helps prevent welders from producing irregular or defective welds.
Number of Lessons 19
- SMAW Overview
- SMAW Base Metals
- SMAW Electrodes
- Joint Preparation
- SMAW Basics Review
- Starting the Arc
- Electrode Orientation: Travel and Work Angles
- Electrode Orientation: Push and Drag Angles
- Travel Speed
- Running a Bead
- Terminating the Arc
- SMAW Process Review
- Common Discontinuities: Undercut
- Common Discontinuities: Porosity
- Common Discontinuities: Incomplete and Excessive Penetration
- Common Discontinuities: Incomplete Fusion
- SMAW Discontinuities Review
- Describe SMAW.
- Describe SMAW base metals.
- Distinguish between common SMAW electrodes.
- Describe joint preparation requirements for SMAW.
- Describe the effects of amperage on SMAW welds.
- Describe the effects of voltage on SMAW welds.
- Describe arc starting methods for SMAW.
- Distinguish between the travel angle and the work angle.
- Distinguish between push angle and drag angle techniques.
- Describe travel speed for SMAW.
- Describe how to run different weld beads for SMAW.
- Describe how to terminate the arc and minimize the effects of craters.
- Describe undercut.
- Describe porosity.
- Describe incomplete and excessive penetration.
- Describe incomplete fusion.
Measuring between 0 and 90 degrees. Acute angles are often used for welding work angles and travel angles.
A nonferrous, silvery-white metal that is soft and light. Aluminum is one of the most difficult metals to weld.
The amount of current flowing in a circuit. Amperage is measured in amperes (A), or amps.
A handheld power tool that uses an abrasive wheel to remove material from the surface of an object. An angle grinder can be used to remove heavy rust, primer, or paint from the surface of a workpiece before welding.
The area in which electricity transfers from the electrode to the workpiece. The heat generated by the arc melts the base metals and filler metal during SMAW.
A condition that occurs when the arc does not follow its intended path from the electrode to the workpiece. Arc blow can cause excessive spatter, incomplete fusion, and porosity.
The distance that electricity must travel from the tip of the electrode to the weld puddle. Longer arc lengths yield higher levels of voltage.
A method of moving the electrode along the workpiece that points the electrode opposite the direction of travel. The backhand technique uses a drag angle.
Metals that are welded together to form a joint. The base metal and its properties influence the type of welding and the type of electrode that should be used.
A metal removal process that produces an angled surface on the edge of an object. Beveling allows welders to access joints made from thicker base metals more easily.
A discontinuity that occurs when weld metal from one side of a joint melts through to the other side, leaving an open hole. Burnthrough is caused by excessive penetration, but not all excessive penetration results in burnthrough.
A joint created between two parts that lie in the same plane. Butt joints are simple, common joints.
A common nonmetallic element that is combined with iron to create steel. Increasing the carbon content of a metal typically increases hardness.
A common metal that is an alloy of iron and carbon and contains less than 3% alloying elements other than iron and carbon. The amount of carbon in a carbon steel determines its hardness.
An alloy of iron, carbon, and silicon that contains at least 2.0% carbon. Cast iron offers heat resistance and compressive strength.
complete joint penetration
CJP. A weld condition that occurs when weld metal extends throughout the full thickness of the base metals, completely filling the joint. Welds that require complete joint penetration and are welded from only one side of the joint may use weld backing.
An electrode that conducts electricity to the arc but also melts into the weld as filler metal. SMAW consumable electrodes also provide shielding that protects the arc and weld puddle.
Curving outward like the exterior surface of a circle or sphere. An overly convex weld is often considered a discontinuity or defect.
Fractures that develop in a weld after it solidifies completely. Welds with high hardness are prone to cracking.
An undesirable depression in a weld bead. A crater can cause cracking if it is not properly filled.
The flow of electricity through a circuit. Current strength is known as amperage and is measured in amperes (A), or amps.
An irregularity in the specified and expected composition of a weld that exceeds the part design's tolerances. A defect is an unacceptable discontinuity.
A material that removes nitrogen from the molten weld puddle. Denitrifiers prevent nitrogen from ruining a weld bead.
A material that removes oxygen from the weld puddle. Deoxidizers prevent oxygen from ruining a weld bead.
The rate at which an electrode melts into the molten weld puddle to form a weld. Deposition rate is measured in pounds per hour (lb./hr.) or grams per minute (g/min).
direction of travel
The direction in which welding occurs. The travel angle determines whether the electrode points towards the direction of travel or away from it.
An irregularity in the specified and expected composition of a weld. A discontinuity is not always a defect.
A travel angle that points the electrode opposite the direction of travel. Drag angles are used with the backhand technique.
An imaginary line that runs through the center of an electrode from one end to the other. The electrode axis forms one side of both the work and travel angles.
The insulated handle that clamps onto the SMAW electrode. The electrode holder is connected to the power source during welding to control the arc.
The position of the electrode in relation to the workpiece and direction of travel. Electrode orientation includes the work angle and the travel angle.
A condition that occurs when a weld bead curves outward too far from the surface of the workpiece. Excessive convexity can be caused by using a short arc with insufficient voltage.
A discontinuity that occurs when the weld metal from one side of a joint melts through to the other side. Excessive penetration can be caused by too much heat, slow movement, or poor joint alignment.
The exposed surface of a weld. The face of a weld may be flat, convex, or concave.
An SMAW electrode that fills a joint quickly due to the addition of iron powder in the flux. Fast-fill electrodes melt quickly and are ideal for large workpieces.
An SMAW electrode that solidifies quickly. Fast-freeze electrodes are ideal for overhead welding and correcting poor fit-up and gaps.
A metal that contains iron. Ferrous metals are the most common type of welded materials.
A metal that is added to a weld and has properties similar to those of the base metals. Filler metal often adds to the strength and mass of the welded joint.
An SMAW electrode that has both fast-fill and fast-freeze characteristics. Fill-freeze electrodes both fill a joint relatively quickly and solidify relatively quickly.
Welding that is performed from the upper side of the joint. In flat-position welding, the face of the weld is horizontal.
A nonmetallic material used to protect the weld puddle and arc from atmospheric contamination. SMAW uses electrodes that have flux-coated cores.
A method of moving the electrode along the workpiece that points the electrode in the direction of travel. The forehand technique uses a push angle.
An extra, undesirable space between mating parts. Gaps can be corrected by SMAW with a fast-freeze electrode.
The use of an abrasive to cut the surface of a workpiece and change its shape. Grinding can be used to shape workpieces before welding or remove undercut.
The angle of the groove between two workpieces being welded together. Increasing the groove angle can improve joint access when welding thicker metals.
A weld made in the opening between two parts that provides space to contain weld metal. Groove welds are used on all joints except lap joints.
The amount of thermal energy transferred to the workpiece during welding. Heat input is measured in kilojoules per inch (kJ/in.) or kilojoules per millimeter (kJ/mm).
Welding that is performed on the upper side of a horizontal surface and against a vertical surface. Horizontal-position welding is often used for fillet and groove welds.
The lightest and most abundant element in the universe. Excess hydrogen in weld metal can cause cracking and porosity.
inches per minute
ipm. A unit of measurement for speed that indicates how many inches of a joint are welded in one minute. Welding procedure specifications express travel speeds in inches per minute or millimeters per second.
A weld discontinuity that occurs when the weld metal and base metal or adjoining weld beads are not fully fused. Incomplete fusion is caused by faulty operator technique, improper base metal preparation, insufficient welding heat, lack of access to adjoining beads, and improper joint design.
incomplete joint penetration
IJP. A discontinuity characterized by an unpenetrated and unmelted area in a joint that occurs when weld metal does not extend through the full thickness of the joint. Incomplete joint penetration can result from insufficient welding heat, improper joint design, and improper lateral control of the welding arc.
The configuration in which two or more workpieces are joined. There are five basic welding joint types: butt, corner, edge, lap, and T-joints.
The edge of the weld puddle that is farthest from the finished weld bead. Keeping the arc on the leading edge of the weld puddle helps prevent discontinuities.
A carbon steel that contains less than 0.30% carbon. Low-carbon steels are generally tough, ductile, and easily welded.
An SMAW electrode that limits the amount of hydrogen in the weld metal to produce high-quality welds. Low-hydrogen electrodes are ideal for metals that are susceptible to cracking and welding in awkward positions.
A process that uses an electrically powered machine or tool to remove metal from a workpiece. Mechanical cutting methods include machining, shearing, sawing, and grinding.
millimeters per second
mm/s. A unit of measurement for speed that indicates how many millimeters of a joint are welded in one second. Welding procedure specifications express travel speeds in millimeters per second or inches per minute.
A weld that is formed by running two or more weld beads over top of one another. Multiple-pass welds often use both stringer and weave beads.
A nonferrous, hard, silver-white metal that is easily manipulated. Nickel is often used in alloys.
A colorless, odorless, tasteless gas that naturally makes up 78% of breathable air. Nitrogen can ruin a weld bead, so SMAW electrodes often contain elements to de-nitrify the molten metal.
A metal that does not contain a significant amount of iron. Common nonferrous metals include aluminum, titanium, copper, and nickel.
A concentration of stress caused by an irregularity that weakens the surrounding metal. A notch effect can be caused by undercut in a weld.
Moving back and forth from side-to-side. Oscillating an electrode from side-to-side along a joint will create a weave bead.
Welding that is performed in a position that is not one of the classified positions. Out-of-position welding often uses electrodes that have smaller diameters to prevent spillage.
Welding that is performed from the underside of a joint. Overhead-position welding requires extra safety precautions.
A weld discontinuity in which the weld metal protrudes beyond the weld toe or weld root. Overlap is nearly always unacceptable in a finished weld.
A thermal cutting process that uses a flame produced by a mix of oxygen and fuel gas along with a high-pressure stream of oxygen. Oxyfuel cutting is sometimes called flame cutting or gas cutting, but these terms are non-standard.
A colorless, odorless, tasteless gas that naturally exists in the atmosphere. A small amount of oxygen is sometimes used for shielding, but too much oxygen causes cracking, porosity, and rusting in the welded metals.
The depth to which the arc heat melts the joint below the surface of the base metals. The amount of amperage directly affects weld penetration.
An intersection of two lines or objects that meet at right angles to one another. Perpendicular lines create angles measuring exactly 90 degrees.
A thermal cutting process that uses plasma, which is a jet of ionized gas, to cut metal. Plasma cutting is a quick process that creates high-quality cuts.
A discontinuity characterized by the appearance of tiny voids in a weld bead, resulting from trapped gases in a material. Excessive porosity can weaken a weld.
Having many openings or voids. Porous welds have reduced strength and reliability.
The device that provides the electricity needed to perform arc welding. For SMAW, the welder sets the amperage on the power source.
A travel angle that points the electrode in the direction of travel. Push angles are used with the forehand technique.
An angle that measures exactly 90 degrees. A right angle is formed by two perpendicular lines or objects.
An electrode-storage device that maintains temperatures from 250-300°F (121-149°C). Low-hydrogen electrodes are stored in rod ovens to prevent the flux from absorbing moisture.
The exposed surface at the back of a weld. The root face is exposed by the root opening.
A scrap piece of base metal that is tack-welded onto the end of the workpiece to allow the welder to terminate the arc there. Using run-off tabs prevents craters from forming on the workpiece.
A method of starting the arc in which the welder quickly moves the electrode along the workpiece in a curved motion. With the scratching method, the welder holds the electrode at an angle and strikes the workpiece slightly ahead of where the arc should start.
A type of welding process that is partially controlled by computerized or robotic systems. In semi-automatic welding, the welder is responsible for controlling the position of the welding gun as well as the direction and speed of travel.
shielded metal arc welding
SMAW. An arc welding process that uses a flux-coated electrode. Shielded metal arc welding is also referred to as stick welding or manual welding.
A gas that protects the weld puddle and arc from reacting negatively with the atmosphere. Shielding can be provided by an external supply of gas or by a type of flux material.
A weld that is formed by running a single weld bead. Single-pass welds often use stringer beads.
Cooled flux that forms on top of the weld bead. Slag protects cooling metal and is then chipped off.
A weld discontinuity that occurs when flux residue is trapped between two layers of weld metal. Slag inclusions can negatively affect the strength and integrity of a welded joint.
Shielded metal arc welding. An arc welding process that uses a flux-coated electrode. SMAW is also referred to as stick welding or manual welding.
Liquid metal droplets expelled from the welding process. Spatter can leave undesirable dots of metal on a workpiece surface.
square groove weld
A groove weld made in a square-shaped opening. Square groove welds use base metals with straight edges that are slightly separated.
A type of steel that contains at least 10.5% chromium and exhibits excellent hardness and corrosion resistance. Stainless steel can be welded with many different welding processes.
An alloy of iron and carbon containing less than 2.0% carbon. Steels often contain other elements to enhance various aspects of the metal.
A weld bead formed by moving the electrode in a straight line along the joint. Stringer beads are the most common beads used in SMAW.
A method of starting the arc in which the welder quickly moves the electrode straight downward to contact the workpiece. With the tapping method, the welder holds the electrode perpendicular to the workpiece and strikes it at the place where the arc should start.
A cutting process that uses heat to remove metal from a workpiece. Thermal cutting processes include oxyfuel, air carbon arc, plasma arc, and laser beam cutting.
A joint created between the edge of one part and the surface of a second, perpendicular part that resembles the letter "T." T-joints are very common joints that are simple to create.
The acute angle between the electrode axis and a line vertically perpendicular to the weld axis. The travel angle points the electrode either in the same direction as the direction of travel or in the opposite direction.
The rate at which the welder moves the electrode along the joint to make a weld. Travel speed determines the size of the weld bead.
An unintended void left along the edge of a finished weld. Different amounts of undercut may be acceptable, depending on the welding code and application.
Welding that is performed on a vertical surface, moving up or down. Vertical-position welding is more difficult than flat- or horizontal-position welding.
Welding that progresses upwards along a vertical surface. Vertical-up welding uses a push angle measuring between 5 and 10 degrees.
The electrical force or pressure that causes current to flow in a circuit. Voltage is measured in volts (V).
A weld bead formed by moving the electrode side to side along the joint in an oscillating motion. Weave beads are often used for the second and subsequent passes of an SMAW weld.
An imaginary line that runs through the center of a weld from one end to the other. The weld axis and the electrode axis are used to determine the work and travel angles.
A strip of metal located on the side of the joint opposite the weld that stops molten metal from escaping through the joint. Weld backing is used for complete penetration welds.
The end product of a joint that has been welded. Weld beads can be flat, convex, or concave in shape.
The small area of molten metal that is created by the heat of the arc during welding. The cooled weld puddle forms the permanent joint.
The point at which a weld intersects the surfaces of the base metals, opposite the face of the weld. Weld backing prevents molten weld metal from spilling out of open weld roots.
The point at which a weld's face meets the base metals. Weld toes can experience cracking and undercut.
The ability of a material to be welded under imposed conditions into a specific, suitable structure and to perform satisfactorily for its intended use. Weldability varies based on the type of metal being welded, its thickness, and environmental conditions.
A collection of laws or standards that outline practices for a particular welding application. Welding codes ensure safe welding practices and high-quality welded products.
The position in which a welder performs a weld. Welding positions include overhead-, vertical-, flat-, and horizontal-position welding.
welding procedure specifications
WPSs. A written document that contains all the necessary and specific information for creating a qualified weld. A welding procedure specification must be approved and tested before welding can begin.
A method of running a weld bead by moving the electrode in a circular motion in the weld puddle and withdrawing it slightly. Whipping is required to run stringer beads with fast-freeze electrodes.
A hand tool with wire filaments used to remove dirt, light rust, and other loose materials. A wire brush may be used to clean the surfaces of base metals before welding.
The acute or right angle between the electrode axis and a line horizontally perpendicular to the weld axis. The work angle positions the weld bead on the joint.