What should be the depth of penetration when making a fillet weld?

The appropriate depth of penetration for a fillet weld, which is a common type of joint used in welding, is typically around 25 to 50 percent of the base metal thickness. This range ensures that the weld effectively fuses the two materials together while providing adequate strength and integrity.

If the penetration is too shallow, the weld may not fully bond the materials, leading to potential failure under load or stress. Conversely, excessive penetration beyond 50 percent could lead to distortion or increased weld stress and may negatively impact the overall properties of the weld joint.

This guideline balances the need for sufficient strength with the practical limitations of welding techniques, material behaviors, and the characteristics of the fillet weld itself. Hence, a penetration depth of 25 to 50 percent is optimal for ensuring a robust and reliable fillet weld.