Steel of high speed tool is the cutting tool steel of a kind of high end, have good wearability and obdurability, but if aborning does not add an attention, the blemish such as easy meeting occurrence crackle, cause discard as useless. Because,this basically is: 1, plasticity is low. The alloying element of high-speed steel is much, especially the foreign matter element such as S, Ph, Sn is more, weaken the adhesion between grain easily to cause plasticity to reduce. 2, be out of shape fight muscularity. The alloy part of high-speed steel is complex, recrystallization speed slow, temperature is high, in be out of shape be had below temperature taller be out of shape fight force. 3, forging temperature range is narrow. High-speed steel heats temperature is exorbitant, easy overheat, burn too, temperature stopping forge is too low, can produce phenomenon of thick any crystalline substance, theoretic high-speed steel forgings temperature range is very narrow, be in commonly 200-280 ℃ . 4, thermal conductivity is poor. The thermal conductivity of high-speed steel relatively carbolic steel is a lot of lower, heat in 600-900 ℃ need is slow, can cause temperature stress otherwise, bring about metallic brittleness to happen. Relevant precautionary measures is: 1, strict to the metallic content of the raw material of high-speed steel control. If stannic content wants strict control,be in 0. 08% the following. 2, formulary ingot casting should gather up after skin or emery wheel clear, ability heats forging, in order to improve the performance when high-speed steel is machined. 3, control high-speed steel heat temperature and heat preservation time, be out of shape temperature, use much fire to forging. 4, casting base unplugs when growing, begin to answer tat, after organization of the appearance that wait for casting gets proper and broken plasticity rises with place, increase deflection again. Free forge unplugs when growing, every fire second deflection control is inside times limits of 2-4, answer to send into to the rear from the head. 5, forginging when high-speed steel, decrease to come back continuously in the same position of raw material change form frequency, the provision is little at 8. 6, industry pattern should undertake warm-up, warm-up temperature is controlled commonly for 150-300 ℃ . CNC Milling