Historians and archaeologists generally agree that iron replaced bronze as the metal of choice for crafting tools.
Bronze is composed of copper and tin, both of which are quite soft metals. A tool made of bronze would not have held up for very long without becoming dented, dull, or possibly breaking. Bronze has some advantages over iron, as it resists corrosion and requires a lower temperature for smelting. However, bronze really fell out of favor due to resource pressure. Copper and tin are not often found in the same geographic area, and natural resources were often quickly depleted. This resource pressure likely lead people to take up iron instead as it is a rather plentiful resource and has the capability to be sharpened. Iron didn't require another material to be alloyed with (as in the combination of copper and tin to make bronze) which would cut down on production time and resource requirements. Until people figured out how to alloy iron with carbon to make steel, iron tools were relatively on par with bronze ones, and it would have been a matter of resource and trade stress that made a culture prefer one over the other.