Fillet weld
A joint connecting two components set at roughly right angles to each other. Unlike butt welds, it usually does not require complex edge preparation.
A fillet weld joins two parts that are at right angles or in a T-shape. You melt the edges and filler material, the weld pool fills the corner and solidifies into a triangular weld. The load-bearing size is the throat thickness, the so-called a-dimension – that is the height of the imaginary isosceles triangle in the weld. Force is transmitted via shear stresses in this area. Be careful not to weld too cold and too fast, otherwise you'll have lack of fusion at the root. The weld may look good but won't carry anything. Equally critical is too small a throat thickness or undercut at the weld toes – it will tear under load. With thick plates, watch the heat input so the heat-affected zone doesn't become too hard and crack-sensitive. Keep the joint surfaces clean of rust, oil, and scale, and weld with a steady hand. Guide the electrode or torch so that both edges are melted evenly. For large weld cross-sections, use multiple passes to stay in control of distortion and heat.