What element is critical for the strength of fillet welds?

The strength of fillet welds is significantly influenced by thickness. A thicker weld typically provides a stronger joint because it has more material to absorb stresses and distribute loads. The amount of weld metal present directly affects the fillet weld's ability to withstand tension and shear forces. Thicker welds also reduce the risk of defects like undercuts or incomplete fusion, which can compromise strength.

While length, material type, and heat input also play roles in the effectiveness of a fillet weld, thickness is the key factor that primarily determines the weld's overall strength. Length might influence the surface area but does not inherently improve the weld's ability to resist failure. Material type is important for compatibility and performance under specific conditions, but without sufficient thickness, even the best materials may not contribute to a strong weld. Heat input is crucial for ensuring proper fusion and preventing defects, but once again, the thickness of the weld directly correlates to how much load it can withstand.