Craftsman Shielded Metal Arc Welding cheat sheet

SMAW arcs emit ultraviolet and infrared radiation; filter lens shade must increase with welding current, and bystanders need screens or appropriate eye protection.

Zinc oxide fume from galvanized steel causes metal fume fever; the coating must be removed from the weld zone or controlled by local exhaust ventilation.

Stainless steel welding fume can contain hexavalent chromium and nickel; local exhaust ventilation and respiratory protection are selected from exposure monitoring.

Confined-space entry requires atmospheric testing: oxygen 19.5–23.5% by volume, flammable gas below 10% LEL, and contaminant levels below exposure limits.

A fire watch is required when sparks can ignite combustibles; NFPA 51B uses 35 ft (11 m) as the typical spark travel distance.

Manual arc welding power sources are limited to 80 V AC and 100 V DC open-circuit voltage under OSHA 1910.254.

Electrode holders must be insulated and fully cover the electrode; damaged cable insulation and wet gloves increase electric-shock risk.

Chlorinated solvents must not be used near the arc; ultraviolet radiation can decompose them into toxic phosgene gas.

Heat input (kJ/in) = (arc voltage × amperage × 60) / (travel speed in in/min × 1000).

DCEP is electrode positive and DCEN is electrode negative; electrode polarity affects penetration, deposition, and arc stability, and many SMAW electrodes specify DCEP.

Arc voltage rises as arc length increases; long arcs widen the bead, increase spatter and fume, and raise the risk of undercut and porosity.

For a constant-current source, arc current is set on the machine; arc voltage is determined mainly by arc length and electrode type.

Increasing travel speed reduces heat input per unit length and bead width; excessive speed can cause undercut and lack of fusion.

AC reverses polarity each half-cycle; the arc must reignite at each current zero, so AC arcs are less stable than DC arcs on some electrodes.

Arc blow is magnetic deflection of the arc; DC welding, asymmetric ground paths, and residual magnetism increase it, while AC and balanced grounding reduce it.

Distortion results from nonuniform heating and cooling; balancing welds about the neutral axis, backstepping, and preset reduce it.

SMAW uses a constant-current (drooping) power source; the steep volt-ampere curve limits current changes when arc length varies.

Duty cycle = (arc time in 10 min / 10 min) × 100%; a 60% rated machine can weld 6 min at rated current in a 10-min period.

OSHA 1910.254 limits manual arc welding open-circuit voltage to 80 V AC and 100 V DC.

Transformer-rectifier machines convert AC input to DC output; inverters increase frequency and reduce transformer size and weight.

AC SMAW output is usually 60 Hz; DC output polarity is selected by cable connection or a polarity switch.

The nameplate lists rated output, duty cycle, open-circuit voltage, input voltage, phase, and frequency; output cannot exceed the rating continuously.

Engine-driven generators are used where line power is unavailable; auxiliary power ratings are separate from welding output.

Remote contactor or amperage control allows current adjustment at the work location; electrode and work cables must match the rated current.

Low-carbon steel has less than about 0.30% C; medium-carbon steel has 0.30–0.60% C; high-carbon steel has above 0.60% C; weldability and cracking risk worsen as carbon rises.

A36 is a structural carbon steel with a 36 ksi minimum yield strength; ASTM A36 chemistry is not the same as AISI 1018 chemistry.

AISI 1018 is low-carbon and AISI 1045 is medium-carbon; 1045 usually needs preheat and controlled cooling to avoid martensite cracking.

Type 304 is austenitic stainless steel with about 18% Cr and 8% Ni; Type 316 adds molybdenum for chloride resistance.

Aluminum 6061 is heat-treatable; its oxide film melts far above the base metal and must be removed before welding.

Cast iron contains high carbon and is crack-sensitive; SMAW repair often uses nickel-based electrodes, preheat, and slow cooling.

CE = C + Mn/6 + (Cr + Mo + V)/5 + (Ni + Cu)/15; higher CE indicates greater need for preheat and hydrogen control.

Spark testing, magnet testing, fracture appearance, and chemical analysis are used to identify or confirm base metals.

Clean at least 1 in (25 mm) beyond each joint face; oil, grease, paint, rust, moisture, and mill scale are hydrogen and porosity sources.

Stainless steel requires dedicated stainless brushes and grinding wheels; carbon steel contamination causes rust and corrosion.

Aluminum oxide must be removed by stainless brush or chemical cleaning; the oxide melts above 3,600°F while aluminum melts near 1,220°F.

Galvanized coating must be removed from the weld zone; zinc fume causes metal fume fever and interferes with arc stability.

Chlorinated solvents must be completely evaporated before welding; UV radiation can create toxic phosgene.

Preheating can drive off surface moisture and reduce hydrogen cracking; it does not replace cleaning.

Bevel and root faces must be free of slag, burrs, and tears that can trap inclusions.

Five basic joint types are butt, lap, tee, corner, and edge; weld type is independent of joint type.

A typical single-V groove for SMAW uses a 60° included angle, root face about 1/16–1/8 in, and root opening about 1/16–1/8 in; drawings govern.

Root opening controls penetration; too small restricts arc access, while too large promotes burn-through and excess melt-through.

Tack welds must be clean, fused, and of sufficient size; cracked or undercut tacks are removed before welding.

Misalignment and hi-lo in pipe reduce root penetration and increase stress; fit-up within code tolerance is required.

Backstep, balanced, and skip welding distribute heat and reduce distortion.

Restraint increases residual stress; pre-setting or allowing shrinkage can reduce distortion.

Backing may support the root; it must be clean and compatible, and removable backing must be removed when specified.

AWS A5.1 E7018: 70 ksi minimum tensile strength, all-position, low-hydrogen iron-powder coating, usable on AC or DCEP.

E6010: 60 ksi minimum tensile strength, all-position, high-cellulose sodium coating, DCEP, forceful arc, and deep penetration.

E6011: high-cellulose potassium coating, usable on AC or DCEP, often selected when only AC power is available.

E6013: high-titania potassium coating, AC or DC, soft arc, and shallow penetration; often used on sheet metal.

E7024: high iron powder, limited mainly to flat and horizontal fillet welding, and capable of high deposition.

Low-hydrogen electrodes must be stored dry; holding ovens commonly run 250–300°F, and rebaking follows manufacturer instructions.

Electrode size is the core wire diameter; current range increases with diameter and is printed on the package.

Moisture on cellulosic electrodes affects arc behavior; storage must prevent condensation and coating damage.

For a 90° fillet, work angle is 45°; drag angle is typically 5–15° with the electrode tilted back along the travel direction.

Short arc length reduces spatter and fume and improves control; long arc raises voltage and can cause undercut and porosity.

Vertical-up welding uses lower current and a weave that lets the puddle freeze; vertical-down is faster but gives less penetration.

Overhead welding uses lower current, short arc, and tight control to keep the puddle from sagging.

A root keyhole indicates complete root penetration; loss of keyhole can mean incomplete penetration or burn-through.

Slag must be removed between passes; trapped slag causes inclusions and lack of fusion.

Restart by striking ahead of the crater and returning into it; this prevents a cold lap at the tie-in.

Weave width is limited by code or procedure; excessive weaving can reduce penetration and increase heat input.

VT is visual inspection of surface condition, size, and profile; it is performed before, during, and after welding.

PT detects surface-breaking flaws in nonporous materials; MT detects surface and near-surface flaws in ferromagnetic steel.

UT uses high-frequency sound for internal flaws; RT uses radiation and is sensitive to density changes and porosity.

Porosity is gas entrapment; slag inclusion is nonmetallic material trapped in the weld.

Lack of fusion is incomplete bonding between weld metal and base metal or between passes; incomplete penetration leaves the root unfused.

Undercut reduces throat thickness and creates a stress concentration; cracks are planar and generally rejectable.

A discontinuity is any interruption in uniformity; it becomes a defect only when it exceeds acceptance criteria.

Fillet weld size is measured by leg length or throat; throat = 0.707 × leg for a 90° equal-leg fillet.

AWS symbol: the arrow line points to the joint; the reference line carries the weld symbol; the tail holds process or specification references.

The arrow side is the side the arrow points to; the other side is opposite, and AWS A2.4 defines symbol placement for each.

Fillet weld symbol: size is leg length; length and pitch follow the size, with pitch used for intermittent welds.

A circle at the reference-line junction means weld all around; a flag means field weld.

Groove symbols include V, bevel, U, J, flare-V, and square; included angle and root opening are specified.

A WPS lists welding variables; a PQR records qualification test results; welder performance qualification is separate.

AWS D1.1 prequalified WPS are limited to specified steels, processes, positions, and joint details; outside those limits requires qualification.

Drawing dimensions govern over scaling; welding symbols and notes take precedence in the order stated by the contract drawings and code.