You can tell by the weight, if its really light its likely aluminum or magnesium alloy. If it has weight to it, it's likely ferrous.
Really no chinese material should be trusted with threads, but if it broke when it was a solid piece, depending on the depth of thread, a bolt may cause more damage.
Remember, when you have a strong material and a weak material, the weak material will wear out faster than if it were 2 weak metals together.
So the rule of thumb, is if you can get your threads as deep as your bolt is wide, your good to go. IE a 6mm depth of thread for a 6mm bolt
