___ may be required after weld repair to restore mechanical properties.

___ may be required after weld repair to restore mechanical properties.

• A. Preheating
• B. Annealing
• C. Postheating
• D. Quenching

Answer: (C)

After welding or weld repair, the heat-affected zone and weld metal can end up with altered microstructure and high residual stresses that reduce toughness or ductility. Postheating, or post-weld heat treatment, is used to rearrange the microstructure and relieve those stresses, restoring mechanical properties and improving toughness and ductility. Preheating is done before welding to control cooling rates; annealing broadly softens or relieves stresses but isn’t specifically the step taken after a repair to restore properties; quenching rapidly cools the material to increase hardness, which is the opposite of restoring properties.

After welding or weld repair, the heat-affected zone and weld metal can end up with altered microstructure and high residual stresses that reduce toughness or ductility. Postheating, or post-weld heat treatment, is used to rearrange the microstructure and relieve those stresses, restoring mechanical properties and improving toughness and ductility. Preheating is done before welding to control cooling rates; annealing broadly softens or relieves stresses but isn’t specifically the step taken after a repair to restore properties; quenching rapidly cools the material to increase hardness, which is the opposite of restoring properties.