Certified Welder Base Metal Preparation Questions and Answers

Question 1

A fabricator is preparing to weld hot-rolled carbon steel that has a bluish-gray, flaky surface. What is this layer called, and what is the primary reason it must be removed before welding?

Accepted Answer

Mill scale; it can introduce impurities and cause weld defects like porosity.

Answer

Galvanizing; it produces toxic fumes when heated.

Answer

Anodizing; it prevents proper electrical conductivity.

Answer

Primer coat; it is designed to burn off during the welding process.

Question 2

When preparing a joint on a 2-inch thick, high-carbon steel plate for a critical structural application, which of the following steps is most crucial for preventing hydrogen-induced cracking?

Accepted Answer

Applying a preheat of 250-400°F (121-204°C) before welding.

Answer

Wiping the surface with an oily rag to prevent flash rust.

Answer

Using a coarse grinding disc to create a rough surface for better adhesion.

Answer

Ensuring the root gap is as small as possible to minimize filler metal usage.

Question 3

A welder is tasked with preparing an aluminum base metal for a high-quality TIG weld. Which of the following preparation sequences is correct?

Accepted Answer

Degrease with a suitable solvent, then brush with a dedicated stainless steel wire brush.

Answer

Wire brush with a carbon steel brush, then wipe with a shop rag.

Answer

Grind with a disc previously used on steel, then degrease with a solvent.

Answer

Wipe with a clean, dry cloth only.

Question 4

Which of the following contaminants on a base metal is most likely to cause weld porosity if not properly removed?

Accepted Answer

Moisture, oil, or grease

Answer

Permanent marker ink

Answer

Light pencil marks

Answer

Copper anti-spatter spray

Question 5

In preparing a butt joint for a complete joint penetration (CJP) weld on a 1-inch thick plate, a welder grinds the edges to form a groove. What is the primary purpose of creating this weld groove?

Accepted Answer

To increase the travel speed of the welding process.

Answer

To reduce the amount of filler metal required for the joint.

Answer

To provide a space to hide the root of the weld for aesthetic reasons.

Answer

To allow for proper access and fusion through the entire thickness of the base metal.

Question 6

When using a grinder to prepare a bevel on a steel plate, which of the following is a critical safety and quality practice?

Accepted Answer

Ensuring the prepared surface is smooth and free of deep gouges or grinding marks.

Answer

Removing the guard to get better visibility of the work area.

Answer

Using a grinding wheel with a rotational speed rating lower than the grinder's RPM.

Answer

Applying excessive pressure to speed up the material removal process.

A fabricator is preparing to weld hot-rolled carbon steel that has a bluish-gray, flaky surface.What is this layer called, and what is the primary reason it must be removed before welding?

A fabricator is preparing to weld hot-rolled carbon steel that has a bluish-gray, flaky surface.
What is this layer called, and what is the primary reason it must be removed before welding?