Root Pass: first weld bead of a multiple pass weld. Fuses the two parts together and establishes the depth of weld penetration.
Key hole: electrode is moved in and out of the molten weld pool as the weld progresses along the joint. the edge of metal is burned back slightly by electrode just ahead of the molten weld pool.
Burnthrough: A hole or depression in the root bead of a single groove weld due to excessive penetration.
Hot pass: the welding electrode is passed over the root pass at a higher-than-normal amperage setting and travel rate to reshape an irregular bead and turn out trapped slag
Wagon tracks: A pattern of trapped slag inclusions in the weld that show up as discontinuities in X-rays of the weld
Filler passes: One or more weld beads used to fill the groove with weld metal. Bead must be cleaned after each pass to prevent slag inclusions.
Cover pass: the last layer of weld beads on a multipass weld.
Weld groove: A channel in the surface of a workpiece or an opening between two joint members that provides space to contain a weld.
Back gouging: The removal of weld metal and base metal from the weld root side of a welded joint to facilitate complete fusion and complete joint penetration upon subsequent welding from that side
Preheating: the application of heat to the base metal immediately before welding, brazing, soldering, thermal spraying, or cutting.
Postheating: the application of heat to an assembly after welding, brazing, soldering, thermal spraying, or cutting.
Interpass temperature: in a multipass weld, the temperature of the weld area between weld passes.
Guided-bend specimen: any bend specimen that will be bend-tested in a fixture that controls the bend radii, such as the AWS bend-test figure.
Shielded Metal Arc Welding (SMAW / Stick)
Shielded metal arc welding is when an electric current is used to form an electric arc between the electrode and the metals to be joined.
SMAW arc welding is primarily used to weld iron and steels. It is also the most common form of welding used. Can be used to weld 1/8 in thick or thicker metal.
The basic equipment and supplies needed to stick weld are:
The type of power source or level of electrode depends on the metal to be welded. Some addition equipment that might be useful are chipping hammer, wirebrush, and protective equipment such as a welding shield and welding gloves.
Protective equipment includes:
Scratch Start Technique:
To strike the electric arc when starting a SMAW operation, the electrode is brought into contact with the workpiece, dragged like lighting a match, and then pulled away slightly. If the arc lights and then goes out, that means the electrode was pulled too far away from the base metal. If the electrode sticks to the metal, give a twist and it should come free.
Tapping Technique:
Move the electrode straight down to the base metal. Then lift slightly. The arc should start. If the arc goes out, that means it was lifted too high off the workpiece.
Electric current: flow of electrons
Temperature: the degree or level of thermal energy in a material
Heat: the quantity of thermal energy in a material.
Welding currents:
Weave Patterns
Circular patterns are often used for flat position welds on butt, tee, and outside corner joints, and for buildup or surfacing applications. The circle can be made wider or longer to change the bead width or penetration
“C” and square patterns are both good for most 1G (flat) welds but can also be used for vertical (3G) positions. These patterns can also be used if there is a large gap to be filled when both pieces of metal are nearly the same size and thickness.
“J” patterns work well on flat (1F) lap joints, all vertical (3G) joints, and horizontal (2G) butt and lap (2F) welds. This pattern allows the heat to be concentrated on the thicker plate. It also allows the reinforcement to be built up on the metal deposited during the first part of the pattern. As a result, a uniform bead contour is maintained during out-of-position welds.
“T” patterns work well with fillet welds in the vertical (3F) and overhead (4F) positions. It also can be used for deep groove welds for the hot pass. The top of the “T” can be used to fill in the toe of the weld to prevent undercutting.
Straight step patterns can be used for stringer beads, root pass welds, and multiple pass welds in all positions. For this pattern, the smallest quantity of metal is molten at one time as compared to other patterns. Therefore, the weld is more easily controlled
Figure -8 and zigzag patterns are used as cover passes in the flat and vertical positions. Do not weave more than 2 1/2 times the width of the electrode. These patterns deposit a large quantity of metal at one time.
Information on Welding Discontinuities with pictures or diagrams
Guide to Shielded Metal Arc Welding
