METHOD FOR ROLLING BILLETS MADE OF HYPER-EUTECTOID gamma + alpha 2 ALLOYS AND METHOD FOR PRODUCTION OF BLANKS USED FOR EMBODIMENT THEREOF

摘要

The present invention relates to the pressure processing of metals and alloys and essentially to the processing of alloys containing titanium aluminides TiAl (phase gamma ) and Ti3Al (phase alpha 2)and obtained by a casting method. This invention also relates to a sintering method and can be used in the production of sheets or foils having a regulated structure. The method involves using as a starting blank a blank having a previously prepared fine-granulation structure. The rolling into sheets or foils of a predetermined thickness and with grains of a certain size is carried out in a range of deformation rates of 10<-3> to 10<-1> sec. <-1> and in a temperature range of T* to Te DEG C, wherein T* preferably ranges from 400 to 700 DEG C, while Te is the eutectic conversion temperature. The rolling is carried out in one or several steps during N transitions in isothermal or quasi-isothermal conditions. The preform heating temperature Ti+1 during each following step is selected according to the relation Ti+1 = Ti, where Ti is the preform heating temperature during the previous step, provided that during the first step Ti = To where To is the deformation temperature during the last step when producing a billet by a rolling process. The relations Ti+1 = Ti + DELTA Ti+1 or Ti+1 = Ti - DELTA ti+1 can also be respected, wherein Ti+1 is selected from conditions of allowed grain growth while DELTA ti+1 is selected from the conditions of deformability or deformability and oxidisability reduction of the alloys.