Final answer:
Hacksaw blades can break due to improper tension which makes them susceptible to bending, and using the wrong tooth pitch for the material being cut which can cause the teeth to catch and lead to breakage.
Step-by-step explanation:
There are several reasons why hacksaw blades can break, but I will discuss two primary causes. Firstly, the blade may break due to improper tension. When the blade is not tensioned correctly, it becomes more susceptible to bending and twisting during use, leading to metal fatigue and eventually causing the blade to snap. Secondly, using the wrong tooth pitch for the material being cut can lead to excessive force on the blade teeth. For example, a finer tooth blade designed for cutting thin metal used on a thicker metal can cause the teeth to catch and break off, which can put additional stress on the blade and lead to breakage.