9 CrSi is a common alloy tool steel, which is generally used as a tool for low-speed use such as manual tapping. It is not normal that your product will break down. If you violently fall on the concrete floor, normal products may also be broken. Generally speaking, the hand should be thrown to a height of about 2 meters and landed on the cement board, and it can't be broken before it is qualified. There are many reasons for the fracture of mechanical wires, such as high quenching temperature, large ponytail needle, high brittleness and easy fracture. Poor raw materials, serious segregation, easy to cause fracture. There are many impurities in raw materials, which are easily broken. Generally, tempering at 200 degrees is enough. Your tempering temperature is still relatively high, so it should not be tempering. Related tests can be carried out by metallographic microscope. However, metallographic examination needs technology, martensite structure is not good-looking, and it needs a certain technical content. The horseshoe can't see the needle, otherwise it will overheat. I suggest you find someone who knows about heat treatment to test it, so you can avoid detours. I hope it works for you.