Fillet weld concavity
A concave fillet weld surface, where the weld face curves inward below the line joining the weld toes. It improves the notch behavior but reduces the load-carrying cross-section of the weld.
Physicochemical Mechanism of Action
The concavity of a fillet weld is achieved by the surface curving inward below the line joining the weld toes. This affects notch behavior because it enhances the contact between the parts, making notching easier.
Metallurgical Relevance & Welding Risks
Concavity increases the toughness of the weld through better notch deformation. However, it reduces the load-carrying cross-section because the volume of weld metal is increased. This can lead to lower load transfer capability and, under extreme loads, deterioration of mechanical performance.
Shop Practice & Action Instructions
To optimize the concavity of a fillet weld, pay attention to correct notch geometry. A typical target is a concavity of 0.5 to 1 mm. Excessive concavity can arise from too pronounced a notch or too high a notch pressure and should be avoided. If needed, special tools like notch punches or cutting tools can be used to achieve the desired concavity.