AWS Certified Welder key terms

An arc process in which a covered electrode is consumed and the flux coating produces shielding gas and slag over the molten metal. It is the most common process on structural and pipe certification tests.

An arc process using a non-consumable tungsten electrode and a separate filler rod, usually with argon shielding. It is favored for root passes on pipe and thin base material.

A process where a continuous wire electrode is fed through a gun and shielded by an external gas. It is often used in short-circuiting or spray transfer modes on production welds.

An arc process using a tubular wire filled with flux, which generates its own shielding and slag. It offers high deposition rates on thicker base material and outdoors.

The alphanumeric code stamped on electrode packaging that states tensile strength, welding position, coating type, and current. Decoding it correctly is a routine requirement on certification exams.

The amperage flowing through the arc, which controls penetration and deposition. Direct current electrode negative, direct current electrode positive, and alternating current each change bead shape and penetration.

A gas or gas mixture supplied around the arc to exclude oxygen and nitrogen from the weld pool. Composition influences arc stability, penetration profile, and spatter level.

The way molten metal moves from the wire to the work in GMAW, such as short-circuiting, globular, or spray. Each mode suits different positions, thicknesses, and spatter tolerances.

The non-consumable electrode used in GTAW, often alloyed with thorium or lanthanum. Its tip geometry and cleanliness strongly affect arc stability and weld contamination.

The solidified flux covering a finished bead that protects hot metal and must be removed between passes. Residual slag trapped under later passes creates inclusions and is a common defect cause.

The orientation of the weld axis and face relative to the welder, classified as flat, horizontal, vertical, or overhead. Position affects gravity's pull on the pool and the technique required.

A weld made from the top side with the face upward, designated 1G or 1F. Gravity holds the pool in place, so it is the easiest position and uses the highest deposition settings.

A weld on a vertical surface with the axis roughly horizontal, designated 2G or 2F. The pool tends to sag downward, so travel speed and weave width must be controlled.

A weld made with the axis vertical, designated 3G or 3F, and performed either uphill or downhill. Uphill gives deeper penetration and better fusion; downhill is faster but shallower.

A weld made from below with the face downward, designated 4G or 4F. Gravity pulls the pool away from the joint, demanding low current, tight arc length, and small, fast beads.

Vertical progression from bottom to top, which produces deeper penetration, a narrower bead, and better fusion. It is the standard direction for vertical groove tests on thick sections.

Vertical progression from top to bottom, giving faster travel and a flatter profile but shallower penetration. It is often specified for thin-wall pipe root passes rather than heavy sections.

The distance between the electrode tip and the molten pool. Too long a gap reduces penetration and increases spatter and arc blow; too short a gap risks sticking or stubbing.

The angle of the electrode or torch relative to the weld axis in the direction of travel. It controls bead shape, penetration, and whether the pool is pushed or dragged.

The angle of the electrode or torch relative to the joint surfaces, usually bisecting the included angle. Correct work angle keeps both walls fused and prevents undercut on one side.

Iron-based metal with carbon as the primary alloying element, typically under about 0.3 percent for weldable structural grades. It is the most common base material on entry-level certification tests.

A steel alloyed with chromium, usually 10.5 percent or more, that forms a passive oxide layer for corrosion resistance. It has higher electrical resistance and lower thermal conductivity than carbon steel.

A light, highly conductive metal that forms a tenacious oxide film and conducts heat away rapidly. Its low melting point and lack of color change make pool control difficult for beginners.

The base metal adjacent to the fusion line that is altered by heat but not melted. Its microstructure and hardness can change, affecting toughness and the need for preheat or post-weld treatment.

The wall or plate thickness being joined, which governs joint preparation, preheat need, and current selection. Thicker sections require more passes and greater heat input management.

Heating the base metal before welding to slow cooling and reduce the risk of cracking, especially in thick or high-carbon steel. Minimum preheat temperatures are often specified by code.

The energy delivered per unit length of weld, calculated from current, voltage, and travel speed. Excessive heat input can cause distortion, grain growth, and reduced toughness.

The geometric arrangement of members being joined, such as butt, lap, tee, corner, or edge. Each configuration dictates edge preparation, fit-up, and the number of passes needed.

A weld deposited in a prepared opening between two members, such as a V, U, or J groove. It usually requires full penetration and multiple passes to fill the joint.

A triangular weld joining two surfaces at an angle, sized by its leg length. It carries load through the throat and is the standard joint type for tee and lap configurations.

The first pass deposited in a groove, which establishes penetration and fusion at the joint root. Defects here are hard to repair, so root quality is closely inspected.

The clearance between the two members at the bottom of a groove before welding. Too large a gap causes burn-through; too small a gap prevents full penetration.

The nominal outside diameter of a pipe, which determines whether it is tested in fixed or rotating position. Small-diameter pipe is often welded entirely in the 5G or 6G positions.

A pipe test with the axis horizontal and the pipe fixed so the welder must move around it. It combines flat, vertical, and overhead welding in one joint.

A pipe test with the axis inclined about 45 degrees and the pipe fixed. It is considered the most demanding position because the pool must be controlled through every orientation.

The depth the weld metal extends into the joint root or base metal. Adequate penetration is required for joint strength and is verified by visual or bend testing.

A groove melted into the base metal along the weld toe that is left unfilled. It creates a stress concentration and is a common cause of failed visual inspection.

The rate the arc moves along the joint, which affects bead width, penetration, and heat input. Too fast a speed risks lack of fusion; too slow a speed causes excess reinforcement and burn-through.