Which type of steel has restrictions on the listed joint prep and back-gouging processes?

• A. Stainless steels
• B. Quenched or tempered steels
• C. Aluminum alloys
• D. Mild carbon steel

Answer: (B)

Quenched and tempered steels are heat-treated to achieve high strength and hardness, which makes their microstructure very sensitive to heat and processing near the weld. When you perform joint prep or back-gouging, you introduce heat and mechanical disturbance right at the weld area. This can alter the heat-affected zone, temper or soften surrounding metal in unwanted ways, and even promote cracking if hydrogen is present. To protect the integrity of the weld and preserve the material’s controlled properties, welding procedures impose restrictions on how the joint is prepared and how back-gouging is performed for these steels.

In practice, these restrictions help prevent cracking and loss of toughness in the weld region by guiding acceptable gouging methods, limits on gouge depth, and requirements for heat control (such as preheat, heat input limits, or using low-hydrogen consumables). Other materials have different welding sensitivities, so the specific restrictions described here are tied to the hardened, high-strength behavior of quenched and tempered steels.