Final answer:
A welded joint may develop various properties and defects. Dislocations affect mechanical strength, while the interaction of different metals can influence corrosion resistance. Thermal stress from different expansion coefficients can lead to bonding issues in metal applications.
Step-by-step explanation:
A welded joint may develop various mechanical properties, corrosion resistance, discontinuities, and brittleness factors. When discussing the structure and properties of welded joints, it is crucial to understand how defects such as dislocations can affect the overall mechanical properties. For instance, line defects weaken the structure along a one-dimensional space. Dislocations in a material can directly influence its mechanical strength, ductility, and malleability.
Regarding corrosion resistance, the interaction between different metals, such as the Pb/Fe joints, can cause one metal to corrode faster due to their electrochemical differences. The less active lead (Pb) serves as a cathode and promotes the oxidation of the more active iron (Fe).
Finally, thermal stress can induce various effects in materials, for example, the formation of cracks due to different expansion coefficients. This is significant when creating metal-to-metal or metal-to-bone bonding in clinical applications, such as with implants where finding a suitable coating that doesn't generate stress at the interface is crucial for durability.