456A SMAW Stick

Question 1

What does the 'E7018' electrode designation mean according to CSA/AWS classification?

Accepted Answer

E = electrode, 70 = minimum tensile strength (70,000 psi / 480 MPa), 1 = all-position capability, 8 = low-hydrogen iron powder coating with AC/DCEP

Answer

In the AWS/CSA designation: E = electrode, 70 = minimum tensile strength in ksi (70,000 psi or 480 MPa), 1 = usable in all positions (flat, horizontal, vertical, overhead), 8 = low-hydrogen iron powder coating suitable for AC and DCEP. The E7018 is the most widely used structural electrode in Canadian construction.

Question 2

What is the purpose of the flux coating on a SMAW electrode?

Accepted Answer

To shield the weld pool from atmospheric contamination, stabilize the arc, add alloying elements, and form a protective slag over the cooling weld

Answer

The flux coating serves multiple critical functions: it decomposes in the arc to create a shielding gas that protects the molten weld pool from nitrogen and oxygen contamination, forms a slag that protects the cooling weld, stabilizes the arc, adds deoxidizers and alloying elements, and controls the weld bead profile.

Question 3

Why must low-hydrogen electrodes (E7018) be stored in a heated oven or opened from vacuum-sealed packaging?

Accepted Answer

To prevent moisture absorption by the flux coating, which can introduce hydrogen into the weld and cause hydrogen-induced cracking

Answer

Low-hydrogen electrode coatings readily absorb atmospheric moisture. If used wet, the moisture decomposes in the arc, introducing hydrogen into the weld. Dissolved hydrogen can cause delayed cracking (hydrogen-induced cracking or cold cracking) in the heat-affected zone. CSA W59 requires storage at 120°C to 150°C in a rod oven after opening.

Question 4

What polarity is typically used for E7018 electrodes and why?

Accepted Answer

DCEP (DC Electrode Positive / Reverse Polarity) for deeper penetration and a smoother, more stable arc; AC is also acceptable

Answer

E7018 electrodes perform best on DCEP (reverse polarity) where the electrode is positive and the workpiece is negative. DCEP concentrates about two-thirds of the arc heat at the electrode tip, promoting deeper penetration and better arc characteristics. E7018 is also designed to run on AC, making it versatile for field conditions.

Question 5

What is arc blow in SMAW welding and how can it be corrected?

Accepted Answer

An uncontrolled deflection of the welding arc caused by magnetic fields; corrected by changing ground clamp position, welding toward the ground, using shorter arc length, or switching to AC

Answer

Arc blow is the deflection of the welding arc by magnetic fields created by the DC welding current flowing through the workpiece. Corrections include: repositioning the work lead (ground clamp), welding toward the ground connection, using a shorter arc length, wrapping the work lead around the workpiece, or switching from DC to AC power.

Red Seal Welder 456A Practice Test

Red Seal Welder 456A Practice Test

456A SMAW Stick