Abstract
	The paper presents effect of initial microstructure of two-phase Ti-48Al-2Cr-2Nb alloy on its plasticity in room temperature as well as hot plastic working conditions based on compression tests conducted in room temperature on testing machine INSTRON 4483 and at temperature 1000?C by using Gleeble 3800 system simulator. It was found, that alloy in as cast state does not deforms both on cold, as and hot. It was also stated, that homogenising of the chemical composition and microstructure of the alloy enables limited deformation during the hot working process and hot deformation is possible only after following consecutive multi-stage heat treatment operations. It was showed, that grain refinement of the investigated alloy and increasing thickness of lamellas inits two-phase ?2+? microstructure by multi-stage heat treatment results in significant improvement in its strength and plastic properties at room temperature and the increase in technological susceptibility under hot working conditions. The observations of microstructure after deformation of Ti-48Al-2Cr-2Nb alloy with different initial microstructures indicate that the main mechanism for reconstruction of the alloy microstructure is dynamic recrystallisation process. In microstructure of deformed alloy, the effects characteristic of deformation of the areas with lamellar construction, as well as dynamic recrystallisation and spheroidisation of particular phases take place. The fine-grained, almost completely recrystallised microstructure with spheroidal phase morphology is obtained upon deformation of approx. 70% of the alloy that was previously put to multi-stage heat treatment comprised of homogenising, cyclic heat treatment and under-annealing.