I-CAR AWQT cheat sheet

Shade selection for GMAW follows arc-current rules of thumb: below 60 A use shade 7; 60-160 A use shade 10; 160-250 A use shade 11; 250-500 A use shade 12; above 500 A use shade 13.

For aluminum GMAW at high current, add one shade step above the steel recommendation because aluminum arcs are brighter and produce more UV and fume.

Minimum body protection for GMAW: flame-resistant long sleeves or leathers, leather gloves, closed collar, no cuffs, and trousers without cuffs to shed spatter.

A welding helmet with a proper filter is required whenever an arc is struck; safety glasses with side shields must be worn under the helmet for chipping and grinding.

Fume extraction or local exhaust ventilation is required for GMAW on galvanized, painted, or coated steel; zinc oxide fume causes metal fume fever with flu-like symptoms.

Compressed gas cylinders must be secured upright, kept away from heat and sparks, and fitted with a regulator rated for the gas; never use oil on oxygen fittings.

Before welding on a vehicle, disconnect or protect the battery, disable the airbag system per OEM procedure, and remove or shield fuel lines and plastic trim within spark range.

Fire watch rule: combustible material within roughly 11 m (35 ft) of the arc must be removed or protected; a fire watch is required during welding and for at least 30 minutes after.

Hot work near a vehicle fuel tank or EV high-voltage system requires OEM-specific deactivation; never assume a battery disconnect alone de-energizes an EV pack.

GMAW transfer modes: short-circuit (low current, thin gauge), globular (unstable, avoid), spray (high current, argon-rich gas, flat position), and pulsed spray (spray at lower average current).

Short-circuit transfer requires CO2 or argon/CO2 mix; pure argon in short-circuit produces erratic, spattery arcs on steel.

Polarity for solid-wire GMAW on steel is electrode positive (DCEP); self-shielded flux-cored wire uses DCEN.

Wire feed speed sets current; voltage sets arc length. Increasing WFS raises current and penetration; increasing voltage lengthens the arc and flattens the bead.

Shielding gas flow for GMAW is typically 10-15 L/min (about 20-30 CFH); excessive flow causes turbulence and porosity.

Contact-tip-to-work distance (CTWD) should stay near 10-15 mm (about 3/8-5/8 in); long stick-out reduces current and penetration and increases spatter.

Drive rolls and liners must match wire size and type; knurled rolls are for flux-cored wire, V-groove rolls for solid wire, U-groove for aluminum.

For aluminum, use a push-pull gun or spool gun, a Teflon or nylon liner, and pure argon; aluminum wire is soft and feeds poorly through standard steel liners.

Duty cycle is the percentage of a 10-minute period a machine can weld at rated output; 60% duty at 200 A means 6 minutes welding, 4 minutes cooling.

STRSW passes current through overlapping panels held under electrode force; heat is generated at the faying surface by I squared R (I²Rt), so contact resistance, not bulk resistance, drives the weld.

Weld nugget forms where current density is highest, between the electrode tips; electrode alignment and tip diameter control nugget size and location.

Electrode force must be applied before, during, and briefly after current flow (squeeze, weld, hold, and off time) to forge the nugget and prevent expulsion.

Weld current, weld time, and electrode force are the three primary parameters; increasing current or time raises heat input, increasing force lowers contact resistance and can reduce heat.

Tip diameter and shape must match the OEM specification; mushroomed or contaminated tips reduce current density and produce undersized nuggets.

Shunting occurs when current bypasses the intended weld through an adjacent existing weld or conductive path; space welds at least the OEM-specified distance, often around 25 mm (1 in) or more.

Weld-through primer and adhesives raise contact resistance; only OEM-approved weld-through coatings are permitted, and adhesive must be squeezed out of the weld zone.

Destructive verification uses a peel or chisel test on a representative coupon or first part; nugget diameter must meet the OEM minimum, often around 4 times the square root of sheet thickness in mm.

STRSW on high-strength and ultra-high-strength steels requires OEM-specific schedules; some grades (e.g., boron/alloy steels) may not be spot-weldable and require rivets or adhesives per OEM.

MIG brazing uses silicon bronze (CuSi3) wire with a melting point near 950-1000 C, well below the roughly 1500 C melting range of steel, so the base metal is not melted.

Because the base metal does not melt, the joint is a braze, not a fusion weld; the zinc or coating on galvanized steel is less damaged and the heat-affected zone is smaller.

Shielding gas for silicon bronze is typically pure argon or an argon-rich mix; CO2-rich mixes can oxidize the wire and are generally avoided.

Brazing is a push or forehand technique with a short arc and a slight drag angle; the puddle should wet the joint and flow, not dig into the base metal.

Typical use is on galvanized, high-strength, or coated outer panels where fusion welding would damage the coating or heat-treat the steel; OEM procedures specify where brazing is approved.

Silicon bronze has lower strength than steel welds; it is not a substitute for structural welds unless the OEM procedure explicitly allows it.

Brazed joints require cleaning of the zinc and oxides before painting; residue causes paint adhesion failures, so the braze must be neutralized and primed per OEM.

A brazed joint can be inspected visually for smooth wetting and full joint fill; gaps, cold lap, or porosity indicate insufficient heat or contaminated surfaces.

Mild (low-carbon) steel is readily weldable with GMAW and STRSW; it has low carbon and good ductility, so heat-affected zones are forgiving.

High-strength low-alloy (HSLA) steels gain strength from alloying and grain refinement; welding heat can soften the heat-affected zone, so OEM weld schedules and heat limits apply.

Advanced high-strength steels (AHSS) include dual-phase, TRIP, and martensitic grades; martensitic and boron steels are very sensitive to heat and may be non-weldable by STRSW.

Boron and press-hardened steels (often around 1500 MPa tensile) generally require squeeze-type resistance spot welding with OEM-specific schedules or rivet bonding; fusion welding is usually prohibited.

Galvanized steel has a zinc coating that vaporizes at welding temperatures, causing porosity and fume; remove coating near the weld or use OEM-approved procedures.

Identification methods include OEM repair information, vehicle build sheets, panel markings, magnet tests (ferrous vs non-ferrous), and hardness or spark testing.

Aluminum and steel must never be joined by fusion welding directly; they form brittle intermetallic compounds and require OEM-approved mechanical fasteners or adhesives.

Steel strength grade affects repairability: higher-strength steels often cannot be straightened with heat and must be replaced per OEM sectioning and joining procedures.

Aluminum GMAW uses pure argon shielding gas and DCEP polarity; a push technique with a 10-15 degree travel angle and short arc is standard.

Aluminum oxide melts near 2050 C while the base metal melts near 660 C; the oxide must be removed mechanically before welding because it prevents fusion.

Aluminum has high thermal conductivity, so heat input must be higher and preheat may be required on thick sections; thin sections distort easily.

Common filler for 5xxx and 6xxx aluminum is ER4043 or ER5356; 5356 is stronger and used where higher strength and better color match are needed.

Aluminum wire is soft and requires a spool gun or push-pull system, U-groove drive rolls, and a Teflon or nylon liner to prevent birdnesting.

Aluminum weld defects include porosity from hydrogen, oxide inclusions, and hot cracking; cleaning and dry gas are the primary controls.

Dissimilar-metal joining of aluminum to steel requires OEM-approved methods such as self-piercing rivets, flow-drill screws, or structural adhesives; direct fusion welding is not acceptable.

Some OEM procedures permit MIG brazing or friction-stir or specialized processes for aluminum-to-steel, but only where the OEM repair document explicitly states it.

Aluminum repair requires dedicated tooling and consumables; steel brushes and grinding wheels contaminate aluminum and cause corrosion and weld defects.

Visual inspection checks bead profile, uniformity, width, and toe wetting; a good GMAW bead is slightly convex with smooth ripples and no undercut.

Undercut is a groove melted into the base metal at the weld toe and left unfilled; it reduces section thickness and is a common rejection criterion.

Porosity appears as surface or internal voids from gas entrapment; surface porosity is visible, internal porosity requires destructive or radiographic testing.

Incomplete fusion (lack of fusion) is a cold lap where the weld metal does not bond to the base metal; it is often hidden and is a serious structural defect.

Spatter and arc strikes are surface defects; arc strikes can create hard, brittle zones and stress risers and must be removed or repaired per OEM.

Weld size is measured by leg length or throat thickness for fillet welds and by penetration and width for groove welds; OEM procedures specify minimum sizes.

STRSW inspection includes nugget diameter, indentation depth, and surface discoloration; excessive indentation or expulsion signals parameter problems.

Brazed joints are inspected for full joint fill, smooth wetting, and absence of gaps or porosity; a cold, lumpy bead indicates insufficient heat.

The chisel or peel test is the standard destructive check for STRSW; a chisel is driven between panels and the weld is pried apart to expose the nugget.

Acceptable STRSW nugget diameter is commonly around 4 times the square root of the thinner sheet thickness in millimeters, per OEM specification.

Plug (button) test: the weld should pull a plug from one panel rather than separate at the interface; interfacial separation indicates insufficient heat.

Bend test on a GMAW coupon reveals fusion and ductility; a sound weld bends without cracking, while lack of fusion or porosity opens up.

Macro-etch (cross-section) shows penetration, fusion, and heat-affected zone; it is used for procedure qualification, not routine production.

Defect analysis traces causes: porosity points to gas or contamination, lack of fusion to low heat or poor technique, cracking to restraint or hydrogen.

Destructive tests are performed on representative coupons or first-off parts, not on the finished vehicle structure, unless the OEM procedure requires it.

Recording destructive test results documents process control and supports warranty or repair documentation.

OEM repair procedures are the controlling document; where they conflict with generic guidance, the OEM procedure governs.

Sectioning locations, joint types, and joining methods are specified by the OEM; cutting outside the approved zone can compromise structural integrity.

Heat restrictions on high-strength and AHSS parts limit or prohibit straightening and welding; follow the OEM heat and repair limits exactly.

Corrosion protection must be restored after welding: use OEM-approved weld-through primer, seam sealer, and cavity wax on all repaired joints.

Weld count and spacing on replacement panels must match the OEM procedure; substituting fewer or differently spaced welds changes load path and crash performance.

Pre- and post-repair measuring and dimensional verification confirm the structure is within OEM tolerance before and after welding.

Documentation of the repair, including procedures used, welds, and materials, supports quality control and customer disclosure.

When the OEM procedure is unavailable, the repair should not proceed on structural or safety-critical parts until the correct procedure is obtained.

Shade selection for GMAW follows arc-current rules of thumb: below 60 A use shade 7; 60-160 A use shade 10; 160-250 A use shade 11; 250-500 A use shade 12; above 500 A use shade 13.

For aluminum GMAW at high current, add one shade step above the steel recommendation because aluminum arcs are brighter and produce more UV and fume.

Minimum body protection for GMAW: flame-resistant long sleeves or leathers, leather gloves, closed collar, no cuffs, and trousers without cuffs to shed spatter.

A welding helmet with a proper filter is required whenever an arc is struck; safety glasses with side shields must be worn under the helmet for chipping and grinding.

Fume extraction or local exhaust ventilation is required for GMAW on galvanized, painted, or coated steel; zinc oxide fume causes metal fume fever with flu-like symptoms.

Compressed gas cylinders must be secured upright, kept away from heat and sparks, and fitted with a regulator rated for the gas; never use oil on oxygen fittings.

Before welding on a vehicle, disconnect or protect the battery, disable the airbag system per OEM procedure, and remove or shield fuel lines and plastic trim within spark range.

Fire watch rule: combustible material within roughly 11 m (35 ft) of the arc must be removed or protected; a fire watch is required during welding and for at least 30 minutes after.

Hot work near a vehicle fuel tank or EV high-voltage system requires OEM-specific deactivation; never assume a battery disconnect alone de-energizes an EV pack.

GMAW transfer modes: short-circuit (low current, thin gauge), globular (unstable, avoid), spray (high current, argon-rich gas, flat position), and pulsed spray (spray at lower average current).

Short-circuit transfer requires CO2 or argon/CO2 mix; pure argon in short-circuit produces erratic, spattery arcs on steel.

Polarity for solid-wire GMAW on steel is electrode positive (DCEP); self-shielded flux-cored wire uses DCEN.

Wire feed speed sets current; voltage sets arc length. Increasing WFS raises current and penetration; increasing voltage lengthens the arc and flattens the bead.

Shielding gas flow for GMAW is typically 10-15 L/min (about 20-30 CFH); excessive flow causes turbulence and porosity.

Contact-tip-to-work distance (CTWD) should stay near 10-15 mm (about 3/8-5/8 in); long stick-out reduces current and penetration and increases spatter.

Drive rolls and liners must match wire size and type; knurled rolls are for flux-cored wire, V-groove rolls for solid wire, U-groove for aluminum.

For aluminum, use a push-pull gun or spool gun, a Teflon or nylon liner, and pure argon; aluminum wire is soft and feeds poorly through standard steel liners.

Duty cycle is the percentage of a 10-minute period a machine can weld at rated output; 60% duty at 200 A means 6 minutes welding, 4 minutes cooling.

STRSW passes current through overlapping panels held under electrode force; heat is generated at the faying surface by I squared R (I²Rt), so contact resistance, not bulk resistance, drives the weld.

Weld nugget forms where current density is highest, between the electrode tips; electrode alignment and tip diameter control nugget size and location.

Electrode force must be applied before, during, and briefly after current flow (squeeze, weld, hold, and off time) to forge the nugget and prevent expulsion.

Weld current, weld time, and electrode force are the three primary parameters; increasing current or time raises heat input, increasing force lowers contact resistance and can reduce heat.

Tip diameter and shape must match the OEM specification; mushroomed or contaminated tips reduce current density and produce undersized nuggets.

Shunting occurs when current bypasses the intended weld through an adjacent existing weld or conductive path; space welds at least the OEM-specified distance, often around 25 mm (1 in) or more.

Weld-through primer and adhesives raise contact resistance; only OEM-approved weld-through coatings are permitted, and adhesive must be squeezed out of the weld zone.

Destructive verification uses a peel or chisel test on a representative coupon or first part; nugget diameter must meet the OEM minimum, often around 4 times the square root of sheet thickness in mm.

STRSW on high-strength and ultra-high-strength steels requires OEM-specific schedules; some grades (e.g., boron/alloy steels) may not be spot-weldable and require rivets or adhesives per OEM.

MIG brazing uses silicon bronze (CuSi3) wire with a melting point near 950-1000 C, well below the roughly 1500 C melting range of steel, so the base metal is not melted.

Because the base metal does not melt, the joint is a braze, not a fusion weld; the zinc or coating on galvanized steel is less damaged and the heat-affected zone is smaller.

Shielding gas for silicon bronze is typically pure argon or an argon-rich mix; CO2-rich mixes can oxidize the wire and are generally avoided.

Brazing is a push or forehand technique with a short arc and a slight drag angle; the puddle should wet the joint and flow, not dig into the base metal.

Typical use is on galvanized, high-strength, or coated outer panels where fusion welding would damage the coating or heat-treat the steel; OEM procedures specify where brazing is approved.

Silicon bronze has lower strength than steel welds; it is not a substitute for structural welds unless the OEM procedure explicitly allows it.

Brazed joints require cleaning of the zinc and oxides before painting; residue causes paint adhesion failures, so the braze must be neutralized and primed per OEM.

A brazed joint can be inspected visually for smooth wetting and full joint fill; gaps, cold lap, or porosity indicate insufficient heat or contaminated surfaces.

Mild (low-carbon) steel is readily weldable with GMAW and STRSW; it has low carbon and good ductility, so heat-affected zones are forgiving.

High-strength low-alloy (HSLA) steels gain strength from alloying and grain refinement; welding heat can soften the heat-affected zone, so OEM weld schedules and heat limits apply.

Advanced high-strength steels (AHSS) include dual-phase, TRIP, and martensitic grades; martensitic and boron steels are very sensitive to heat and may be non-weldable by STRSW.

Boron and press-hardened steels (often around 1500 MPa tensile) generally require squeeze-type resistance spot welding with OEM-specific schedules or rivet bonding; fusion welding is usually prohibited.

Galvanized steel has a zinc coating that vaporizes at welding temperatures, causing porosity and fume; remove coating near the weld or use OEM-approved procedures.

Identification methods include OEM repair information, vehicle build sheets, panel markings, magnet tests (ferrous vs non-ferrous), and hardness or spark testing.

Aluminum and steel must never be joined by fusion welding directly; they form brittle intermetallic compounds and require OEM-approved mechanical fasteners or adhesives.

Steel strength grade affects repairability: higher-strength steels often cannot be straightened with heat and must be replaced per OEM sectioning and joining procedures.

Aluminum GMAW uses pure argon shielding gas and DCEP polarity; a push technique with a 10-15 degree travel angle and short arc is standard.

Aluminum oxide melts near 2050 C while the base metal melts near 660 C; the oxide must be removed mechanically before welding because it prevents fusion.

Aluminum has high thermal conductivity, so heat input must be higher and preheat may be required on thick sections; thin sections distort easily.

Common filler for 5xxx and 6xxx aluminum is ER4043 or ER5356; 5356 is stronger and used where higher strength and better color match are needed.

Aluminum wire is soft and requires a spool gun or push-pull system, U-groove drive rolls, and a Teflon or nylon liner to prevent birdnesting.

Aluminum weld defects include porosity from hydrogen, oxide inclusions, and hot cracking; cleaning and dry gas are the primary controls.

Dissimilar-metal joining of aluminum to steel requires OEM-approved methods such as self-piercing rivets, flow-drill screws, or structural adhesives; direct fusion welding is not acceptable.

Some OEM procedures permit MIG brazing or friction-stir or specialized processes for aluminum-to-steel, but only where the OEM repair document explicitly states it.

Aluminum repair requires dedicated tooling and consumables; steel brushes and grinding wheels contaminate aluminum and cause corrosion and weld defects.

Visual inspection checks bead profile, uniformity, width, and toe wetting; a good GMAW bead is slightly convex with smooth ripples and no undercut.

Undercut is a groove melted into the base metal at the weld toe and left unfilled; it reduces section thickness and is a common rejection criterion.

Porosity appears as surface or internal voids from gas entrapment; surface porosity is visible, internal porosity requires destructive or radiographic testing.

Incomplete fusion (lack of fusion) is a cold lap where the weld metal does not bond to the base metal; it is often hidden and is a serious structural defect.

Spatter and arc strikes are surface defects; arc strikes can create hard, brittle zones and stress risers and must be removed or repaired per OEM.

Weld size is measured by leg length or throat thickness for fillet welds and by penetration and width for groove welds; OEM procedures specify minimum sizes.

STRSW inspection includes nugget diameter, indentation depth, and surface discoloration; excessive indentation or expulsion signals parameter problems.

Brazed joints are inspected for full joint fill, smooth wetting, and absence of gaps or porosity; a cold, lumpy bead indicates insufficient heat.

The chisel or peel test is the standard destructive check for STRSW; a chisel is driven between panels and the weld is pried apart to expose the nugget.

Acceptable STRSW nugget diameter is commonly around 4 times the square root of the thinner sheet thickness in millimeters, per OEM specification.

Plug (button) test: the weld should pull a plug from one panel rather than separate at the interface; interfacial separation indicates insufficient heat.

Bend test on a GMAW coupon reveals fusion and ductility; a sound weld bends without cracking, while lack of fusion or porosity opens up.

Macro-etch (cross-section) shows penetration, fusion, and heat-affected zone; it is used for procedure qualification, not routine production.

Defect analysis traces causes: porosity points to gas or contamination, lack of fusion to low heat or poor technique, cracking to restraint or hydrogen.

Destructive tests are performed on representative coupons or first-off parts, not on the finished vehicle structure, unless the OEM procedure requires it.

Recording destructive test results documents process control and supports warranty or repair documentation.

OEM repair procedures are the controlling document; where they conflict with generic guidance, the OEM procedure governs.

Sectioning locations, joint types, and joining methods are specified by the OEM; cutting outside the approved zone can compromise structural integrity.

Heat restrictions on high-strength and AHSS parts limit or prohibit straightening and welding; follow the OEM heat and repair limits exactly.

Corrosion protection must be restored after welding: use OEM-approved weld-through primer, seam sealer, and cavity wax on all repaired joints.

Weld count and spacing on replacement panels must match the OEM procedure; substituting fewer or differently spaced welds changes load path and crash performance.

Pre- and post-repair measuring and dimensional verification confirm the structure is within OEM tolerance before and after welding.

Documentation of the repair, including procedures used, welds, and materials, supports quality control and customer disclosure.

When the OEM procedure is unavailable, the repair should not proceed on structural or safety-critical parts until the correct procedure is obtained.