The Study On The Effect Of Cold-deformation And Heat-treatment On The Super-elastic Of TiNiCr Shape Memory Alloys

This article focuses on the effect of cold deformation, middle heat-treatment and aging treatment on the super-elastic of TiNiCr shape memory alloys.The test researches the effect of different cold-deformation on the super-elastic and microstructure of TiNiCr shape memory alloys through tensile test and the photos of TiNiCr metallographic structure. The test shows the super-elastic gets better with the growing of cold-deformation, while the deformation gets to 30% the growing rate gets slow. The cold-deformation can not make TiNiCr show entirety non-line super-elastic. The cold-deformation would separate out a kind of martensite in TiNiCr. When the deformation gets to 27%, the bulk of martensite would grow with the growing of deformation and the dislocation grows all the time.It also researches the super-elastic of TiNiCr shape memory alloys after middle hot-treatment by WDW-10 Electronic Universal Testing Machines and D / max2500PC Automatic X-ray Diffraction (XRD) Machine. The test shows the effect of the different heat-treatment temperature and the keeping warm time on TiNiCr super-elastic is marked. With the growing of temperature and keeping warm time, the elastic turn better first then weakness; When the temperature gets to 430℃and keeping warm time for 10～20min, the samples take on non-line super-elastic entirely. The XRD test proves that the sample would separate out a kind of strengthen phase named Cr₃Ni₂. The peak of this phase gets to maximum, then with the growing of temperature and keeping warm time it would get down. The super-elastic is the best at this condition.To enhance the using performance and the processing property, the article researches the super-elastic of TiNiCr shape memory alloys under different aging temperature by tensile test. The curves show that the elastic turns better with the increasing of aging time at lower temperature (720℃), but when the temperature of aging overrun 720℃the elastic is not increase any more. The samples show entirety non-line super-elastic at 680℃and keeping warm for 60min then 430℃and keep warm for 20min.The sample can not show entirety non-line super-elastic on other aging temperature. Compared with the sample under the mid-temperature, the area of tensile curve grows when the samples show the entirety non-line super-elastic.