FREE Certified Welder Base and Filler Metals Questions and Answers

Question 1

In the AWS classification E7018 for a shielded metal arc welding (SMAW) electrode, what does the '1' signify?

Accepted Answer

The welding position capability.

Answer

In the AWS A5.1 standard for carbon steel electrodes, the third digit indicates the welding position. A '1' signifies the electrode is suitable for all positions (Flat, Horizontal, Vertical, Overhead). The '70' indicates 70,000 psi tensile strength, and the '8' indicates the coating type (low-hydrogen, iron powder) and current.

Question 2

A welder is tasked with joining a 1-inch thick A36 carbon steel plate to an equal thickness of 304 stainless steel plate. Which filler metal is specifically designed for this type of dissimilar metal application?

Accepted Answer

ER309L

Answer

ER309L is specifically formulated for welding austenitic stainless steels to carbon or low-alloy steels. Its higher alloy content prevents the formation of brittle microstructures at the weld interface, which would occur if a carbon steel filler were used. ER4043 is for aluminum, and E6010/E70S-2 are for carbon steel.

Question 3

Which of the following is the primary reason for storing E7018 low-hydrogen electrodes in a temperature-controlled oven after opening the sealed container?

Accepted Answer

To prevent the flux coating from absorbing atmospheric moisture.

Answer

The flux coating on low-hydrogen electrodes is hygroscopic, meaning it readily absorbs moisture. This moisture can introduce hydrogen into the weld pool, leading to hydrogen-induced cracking, a serious weld defect. Storing them in a heated rod oven keeps them dry and maintains their low-hydrogen properties.

Question 4

What is the primary effect of increasing the carbon content in a steel base metal on its weldability?

Accepted Answer

It increases hardness and strength, making it more susceptible to cracking.

Answer

Carbon is the principal hardening element in steel. As carbon content increases, the steel becomes harder and stronger but also less ductile. This increased hardness makes it more prone to cracking in the heat-affected zone (HAZ) during the rapid cooling cycle of welding, thus decreasing its overall weldability and often requiring preheat.

Question 5

A welder must perform a repair on a heavy cast iron machine housing. To ensure a successful weld and prevent the base metal from cracking, what is the MOST critical step?

Accepted Answer

Applying a significant preheat to the area around the repair.

Answer

Cast iron has high carbon content, making it brittle and highly susceptible to cracking from thermal stresses induced by welding. Preheating the base metal to a specific temperature before welding slows the cooling rate of the weld and the heat-affected zone, which significantly reduces thermal stress and helps prevent cracking.

Certified Welder Practice Test

Certified Welder Practice Test

FREE Certified Welder Base and Filler Metals Questions and Answers