SERVICE WELDING GUIDE Caterpillar

Glossary

Usage:

Arc Length - The distance from the end of the electrode core to the surface of the puddle of molton metal. Arc Stream - Molten particles of electrode material flowing from the electrode to the puddle of molton metal. Arc Welding - A process of fusion welding in which the heat from an electric arc is utilized to melt the adjacent surfaces of the pieces to be welded. Axis (of a Joint) - A line through the weld deposit in a joint perpendicular to the cross section at its center of gravity. Back Blow - Deflection of the arc away from the direction of travel. See Magnetic Arc Blow. Back-up Plate - A plate placed behind a wide gap weld joint to retain the molten weld metal and insure complete penetration and fusion at the root of the weld. Base Metal - See Parent Metal. Cold Lap - A void between the weld deposit and the parent metal caused by insufficient fusion. Crater - The depression in a weld deposit caused by displacement of molten weld metal by the force of the arc stream. Depth of Penetration - The distance from the surface of the parent metal to the root of the weld. Electrode Angle - The angle that the electrode makes with the axis of the joint or the surfaces of the weldment members. Flat Position - A joint position where both the axis of the joint and the face of the weld are within 10° of horizontal and the welding is performed on the top of the joint. Flux - Fusible material used in welding to dissolve and facilitate removal of oxides and other undesirable substances. Forward Blow - Deflection of the arc toward the direction of travel. See Magnetic Arc Blow. Fusion - The melting together of parent metal and weld metal. Fusion Welding - Welding by melting the adfacent surfaces of pieces to be joined and allowing the molten metal to mix. Gas Shielding - The protection of molten weld metal from the air with a cloud of gas which is generated by the vaporization of materials in the electrode coating. Gouging - Formation of a chamber or groove by melting and removing a portion of vase metal. Hardsurfacing - The deposition of weld metal on metal surface to obtain desired characteristics or dimensions. Heat Treated Steel - A steel that has been heated, quenched and tempered, or otherwise trated in such a manner that its surface hardness is greater than in the annealed condition. High-Strength Structural Steal - A weldable steel with a minimum yield strength of 45,000 psi and a minimum tensile strength of 70,000 psi. Horizontal Position - A joint position where the axis of the joint is within 10° of horizontal and the face of the weld is between 10° and 90° from horizontal. Interpass Temperature - In a multiple pass weld, the lowest temperature of the weld metal before the next pass is started. Interpass temperature should be measured two inches in from the start end of the preceding pass. Low Hydrogen Electrode - An electrode containing no materials in the coating which will yield hydrogen gas upon vaporization. Low Carbon Steel - Steel containing less than 0.30% carbon. Lead Angle - The angle between the electrode and a line perpendicular to the axis of the joint. Magnetic Arc Blow - Deflection of the arc from its intended path due to concentrations of magnetic force set up in the work by electric current. Medium Carbon Steel - Steel containing 0.30% to 0.54% carbon. Mild Steel - See Low Carbon Steel. Neutral Axis - The line of zero stress in a beam, usually at or near the center of the beam. Overhead Position - A joint position where the axis of the joint is within 10% of the horizontal and the welding is performed on the lower side of the joint. Overlap - Protrusion of weld metal beyond the bond at the top of a weld. Parent Metal - The metal to be welded. Pass - A single longitudinal progression of a welding operation along joint. Porosity - Gas pockets or voids in the weld metal. Shielded Arc Welding - An arc welding process that employs an electrode coated with a material which, when heated, decomposes to form a gas cloud, melts to form a slag covering over the weld or both. The gas cloud and the slag protect the molten weld metal and the arc from elements in the air. Slag - Non-metallic solid material composed of electrode flux and impurities from the joint. In a properly made weld, the slag will lie on top of the weld metal. Slag Inclusion - The entrapment of slag in weld metal or between weld metal and parent metal. Slugged Weld - A weld that has a piece or pieces of material added to it before or during welding resulting in a welded joint that does not comply with design or specification requirements. Spatter - The metal particles expelled during welding which do not form part of the weld. Tack Weld - A weld - usually short - made to hold parts of a weldment in proper alignment until the final welds are made. Transverse Weld - A weld made at approximately right angle to the axis of a beam. Travel Speed - The rate at which the electrode is moved along the length of the weld Underbead Crack - A crack between the weld deposit and the parent metal or in the heat affected zone under the weld deposit. Undercut - A groove melted in the parent metal, adjacent to the toe of a weld, that is not filled with weld metal. Upsetting Metal - The process of shortening and thickening metal by means of the application of pressure. In heat straightening, the pressure is obtained from the thermal expansion of the heated metal. Vertical Position - A joint position where the axis of the joint is between 10° and 90° from horizontal. Warping - An undesirable change in the shape of a weldment due to the forces of expansion and contraction of the weld metal. Weaving - Moving the tip of the electrode back and forth over the joint as the electrode travels along the joint to obtain a wider weld deposit and to control heat input in the joint. Weld Deposit - The material in a welded joint which was melted during the welding process. The weld deposit consists of both electrode metal and parent metal. Weldment - An assembly whose components are joined by welding. Work Angle - In horizontal fillet welds, the angle between the electrode and the vertical plate.