Red Seal Welder flashcards

32 cards. Read the term and the definition here. The deck at the top of this page is optional.

Duty cycle

The percentage of a 10-minute period a welding machine can operate at rated output without overheating. A 60% duty cycle at 200 A allows 6 minutes of welding and 4 minutes of cooling.

Carbon equivalent

A formula combining carbon and alloying elements to estimate hardenability: CE = C + Mn/6 + (Cr+Mo+V)/5 + (Ni+Cu)/15. Values above about 0.40 usually require preheat to prevent hydrogen cracking.

Heat input formula

Heat input in kJ/mm equals voltage times amperage times 60, divided by 1000 times travel speed in mm/min. It controls cooling rate, HAZ hardness and toughness, and must stay within the qualified range.

Hot-work fire watch

A person assigned to watch for fire during welding and for at least 30 minutes after the last arc, then re-inspect the area. Required where combustibles are within 11 m or cannot be shielded.

Cylinder separation rule

Oxygen and fuel-gas cylinders in storage are separated by at least 6 m, or by a non-combustible barrier at least 1.5 m high with a fire-resistance rating of at least 30 minutes.

Constant-current characteristic

A steep volt-ampere curve that holds amperage nearly constant as arc length changes. It suits SMAW and is set by amperage, giving the welder arc-length control.

Constant-voltage characteristic

A flat volt-ampere curve that holds voltage nearly constant as current changes. It suits GMAW and FCAW, where wire-feed speed sets current and the voltage control sets arc length.

Fillet weld symbol size

The leg size is placed to the left of the triangle symbol and the length to the right. A dimension in parentheses after the length is the pitch of an intermittent weld.

Field weld symbol

A flag at the bend of the reference line indicates the weld is made at the site, not in the shop. It overrides shop fabrication and requires field inspection and field conditions.

All-around weld symbol

A circle at the junction of the reference line and arrow means the weld continues around the entire joint. It applies to the whole perimeter, not just the side the arrow touches.

WPS versus PQR

The welding procedure specification is the written instruction the welder follows. The procedure qualification record documents the test that proved the procedure; both are required and the PQR supports the WPS.

Sensitization of stainless

Heating austenitic stainless through roughly 425-870 C precipitates chromium carbides at grain boundaries, leaving chromium-depleted zones that corrode. Low heat input and stabilized grades reduce the risk.

Hydrogen cold cracking

Delayed cracking in steel caused by hydrogen trapped in the weld, a hard microstructure and residual stress. Controlled by dry consumables, preheat, clean joints and sometimes a hydrogen bake-out.

Spray transfer

A GMAW mode with high current and argon-rich gas in which fine droplets transfer axially across the arc. It gives deep penetration and high deposition but is not used for thin sheet or out-of-position work.

Short-circuit transfer

A GMAW mode at low current where the wire touches the puddle and pinches off, transferring metal. It suits thin sheet and all positions but can cause lack of fusion if heat input is too low.

Electrode E4918 meaning

In CSA classification, E4918 denotes a 490 MPa minimum tensile strength, all-position electrode with a low-hydrogen, iron-powder coating. The final digits indicate current type and polarity.

Tungsten electrode polarity

DC electrode negative concentrates heat in the work and is used for steel TIG. Alternating current is used for aluminum because the positive half-cycle breaks up the surface oxide.

Root gap and land

The root gap is the space between the two joint faces at the root; the land is the vertical face below the bevel. Both are set by the WPS and control penetration and burn-through.

Back-step welding

A distortion-control technique where short beads are deposited starting at the far end and progressing toward the start. Each bead shrinks against the previous one and pulls the part straight.

Presetting for distortion

Pre-bending or offsetting the parts opposite the expected shrinkage before welding. The assembly cools into the correct position instead of pulling out of alignment.

Post-weld heat treatment

Controlled heating and cooling of a completed weldment to relieve residual stress and temper the heat-affected zone. Temperature and rate are specified and recorded with thermocouples.

Visual inspection

The first inspection method, performed before and after welding. It checks fit-up, bead profile, undercut, overlap, spatter, arc strikes and surface-breaking defects without special equipment.

Magnetic particle testing

An NDT method that uses a magnetic field and iron particles to reveal surface and near-surface defects. It works only on ferromagnetic metals, not on austenitic stainless or aluminum.

Radiographic testing

An NDT method that passes radiation through the weld onto film or a detector. It reveals volumetric defects such as porosity and slag but is poor at tight planar cracks normal to the beam.

Ultrasonic testing

An NDT method that sends high-frequency sound into the weld and reads reflections. It detects planar defects such as cracks and lack of fusion and can measure their depth.

Bend test purpose

A destructive test that bends a specimen to expose lack of fusion, porosity and incomplete penetration at the root or face. It is part of procedure and welder qualification.

Neutral oxy-fuel flame

A flame with equal acetylene and oxygen, used for general heating and welding. An oxidizing flame has excess oxygen and is used for cutting; a carburizing flame has excess acetylene.

Kerf allowance

The width of material removed by a thermal cut. Layout adds half the kerf to each side of the cut line so the finished part meets the drawing dimension.

Air-carbon-arc gouging

Metal removal with a carbon electrode and a compressed-air jet. It uses DC electrode positive and is used to back-gouge roots and remove defects before re-welding.

Plasma cutting advantage

A constricted-arc process that cuts any conductive metal, including stainless steel and aluminum, with a narrow kerf and high speed. It does not rely on oxidizing the iron.

Travel speed calculation

Travel speed equals wire-feed speed times wire cross-sectional area divided by weld cross-sectional area. It links deposition rate to the joint volume and is used to set the procedure.

Dilution in cladding

The percentage of the weld deposit that comes from melted base metal: base-metal area divided by total weld area times 100. High dilution changes deposit chemistry and corrosion resistance.