How does the grain typically change as successive passes are added in a weld?

How does the grain typically change as successive passes are added in a weld?

• A. A finer grain forms with each additional pass
• B. The grain becomes coarser with more passes
• C. The grain remains unchanged
• D. Grain orientation becomes random

Answer: (A)

With multi-pass welding, each new pass reheats and partially remelts the previously deposited weld metal. As that metal solidifies again, many new grains form, increasing the number of grain boundaries and interrupting the growth of any single grain. The repeated thermal cycles promote recrystallization and new nucleation rather than letting grains simply grow, so the weld metal and nearby heat-affected zone tend to develop a finer grain structure as more passes are added. In short, additional passes lead to a finer grain than a single-pass weld.