Final answer:
Welding can cause thermal stresses (option B) due to varying expansion and contraction from temperature changes, which can lead to damage or failure, especially at interfaces of materials with different expansion coefficients.
Step-by-step explanation:
Welding can cause thermal stresses due to temperature gradients. These stresses occur because when materials are heated, they expand, and when they cool, they contract. In welding, this can cause parts of the metal to expand or contract at different rates, leading to stresses within the material. This is especially a problem when different materials or materials with different properties are welded together, as they may have different expansion coefficients, resulting in a mismatch that can cause damage or failure at the interface.
For example, during the manufacturing process of metal implants for hips and knees, finding a coating for the metal that has similar expansion coefficients is crucial. If the coefficients are too different, the thermal stresses can lead to cracking at the metal-coating interface, compromising the integrity of the implant. Similarly, in everyday experiences like road maintenance, illustrates how thermal stress contributes to the formation of potholes, which are a result of temperature-induced expansion and contraction of the material in pavement.
Understanding thermal stresses is key in many applications to prevent damage and prolong the life of structures and materials.