Method for processing preforms of hyper-eutectoid gamma + alphasub2/sub alloys

摘要

The present invention pertains to the field of metal and alloy processing and can be used for producing preforms and articles having a regulated structure as well as a microstructure with a homogenous fine granulation of up to 0.1 mu m. The preforms of hyper-eutectoid gamma + alpha 2 alloys are first heated and submitted to deformation. The preform deformation is carried out in a temperature range of 700 DEG C to Te DEG C, in which Te is the eutectoid conversion temperature, at rates of 10-4 to 10 sec.-1 in i steps and with n transitions per step, and according to a global deformation ratio SIGMA epsilon ensuring the grinding and size reduction of the grains by recrystallisation. The temperature Ti and the deformation rate epsilon i of a preform in each step are determined according to the experimental results of uniaxial compression on Ni models under isothermal conditions. The size of the grains/colonies is equal to di provided that d1 = dpref. The number of steps is determined from the successive reduction of the grain size in the starting preform until a target value is reached.