Welding joint strength depends on more than just how a weld looks. The real strength comes from correct joint design, proper penetration, good fusion, and understanding how loads act on the joint. Butt joints handle tensile loads well, lap joints mostly face shear, and fillet welds must achieve proper root fusion. A quality weld often fails in the base metal, not the weld itself—that’s the sign of a strong joint. Learn these basics to design safer, stronger welded structures and improve your wel