456A SMAW (Shielded Metal Arc Welding) 1 — Questions and Answers
Question 1: What does the 'E' in an electrode classification such as E7018 stand for?
- Electrode (Correct answer)
- Energy
- Efficiency
- Electrolytic
Correct answer: Electrode
In the AWS/CSA electrode classification system, 'E' stands for electrode, indicating it is a consumable electrode used in the SMAW process.
Question 2: In the electrode classification E7018, what does the '70' indicate?
- Minimum tensile strength of 70,000 psi (480 MPa) (Correct answer)
- 70% deposition efficiency
- Electrode diameter of 7.0 mm
- 70-volt operating range
Correct answer: Minimum tensile strength of 70,000 psi (480 MPa)
The first two digits (70) in E7018 represent the minimum tensile strength of the deposited weld metal, which is 70,000 psi or approximately 480 MPa.
Question 3: What type of current is typically recommended for E7018 low-hydrogen electrodes?
- DCEP (Direct Current Electrode Positive) (Correct answer)
- DCEN (Direct Current Electrode Negative)
- AC only
- Either AC or DCEN
Correct answer: DCEP (Direct Current Electrode Positive)
E7018 low-hydrogen electrodes are recommended for use with DCEP (reverse polarity), which provides deeper penetration and better arc stability. Some formulations also work on AC.
Question 4: What is the maximum moisture content allowed for low-hydrogen electrodes (E7018) before they must be re-dried according to CSA W48?
- They must be stored at 120–150°C and used within 4 hours of removal from oven (Correct answer)
- They can be stored at room temperature indefinitely
- They must be used within 24 hours of opening the container
- Moisture content is not a concern for E7018 electrodes
Correct answer: They must be stored at 120–150°C and used within 4 hours of removal from oven
CSA W48 requires low-hydrogen electrodes to be stored in ovens at 120–150°C and used within a specified time (typically 4 hours) after removal to prevent hydrogen pickup, which can cause hydrogen-induced cracking.
Question 5: Which SMAW electrode would be best suited for welding in all positions including overhead?
- E6013 (Correct answer)
- E7024
- E6020
- E7028
Correct answer: E6013
E6013 is an all-position electrode with a rutile coating that provides good arc control and slag removal, making it suitable for overhead and vertical welding. E7024, E6020, and E7028 are flat/horizontal position electrodes only.
Question 6: What is the primary cause of porosity in SMAW welds?
- Contamination of the weld pool by gas (moisture, oil, or coating breakdown) (Correct answer)
- Excessive amperage settings
- Too fast a travel speed
- Using the wrong electrode diameter
Correct answer: Contamination of the weld pool by gas (moisture, oil, or coating breakdown)
Porosity in SMAW is primarily caused by gas entrapment in the weld pool. Sources include moisture in the electrode coating, oil or grease on base metal, contaminated shielding gas, or improper electrode storage.
456A SMAW (Shielded Metal Arc Welding) 1
What does the 'E' in an electrode classification such as E7018 stand for?