Which of the following makes welded joints particularly strong?

Welded joints achieve their strength primarily through the fusion of base metals. During the welding process, heat is applied to the base metals, causing them to melt at the joint. As the molten metal cools, it solidifies and forms a bond that can be as strong, or even stronger, than the original metals themselves. This fusion creates a continuous connection, effectively eliminating any gaps or weaknesses that might be present in mechanical joints formed by methods such as bolting or the use of adhesives.

In contrast, the other methods mentioned do not involve the same level of integration of the materials. Adhesives bond surfaces without melting them, which may not provide the same structural integrity under stress. Introducing bolts can provide a mechanical connection, but the presence of holes and the clamping force required limits the load-bearing capabilities compared to a welded bond. Lastly, while the malleability of metals allows them to be shaped and deformed under stress, it does not directly contribute to the strength of a welded joint. Thus, the melting and subsequent fusing of materials is key to forming welded joints that are particularly strong.