Effect Of Cryogenic Treatment On Industrial Titanium And Tc4Alloy

Deep cryogenic treatment(DCT), as a process to change the microstructure andimprove the properties of materials, has been widely used in tool and die steel, highspeed steel, cemented carbide etc. However, the research in non-ferrous metals,especially about Titanium alloy is less. Titanium alloys are being increasingly studiedand widely used due to their good corrosion resistance high heat resistance highspecific stiffness and specific strength. It is a new method to adopt DCT and cycleheat treatment in the field of Titanium alloys. Therefore, the research of the effect ofDCT on Titanium alloys is of significance to both theory and practice aspects.In this paper, effect of DCT and cycle heat treatment on TC4as-cast Titaniumalloy has been investigated. The specimens were analyzed by metallographicexamination, X-ray diffraction, microhardness, tensile test. The mechanism of DCTwas expored via observing and comparing the change of properties and thetransformation of microstructure before and after DCT. The results showed:To pure titanium and TC4titanium alloy, The change trend of hardness of thesamples treated by cryogenic environment were similar. The trend was from higher tolower.The hardness of both the commercially pure titanium and titanium alloy TC4has no substaintial decline after cryogenic treatment for60hours,and the besttreatment for the TC4is the cryogenic treatment for15hours after recrystallizationannealing.In the treatment of cryogenic,both in titanium and TC4titanium alloys, Theevolution of grain orientation was found in pure titanium and TC4titanium alloy.Themajor crystal face (100),(002),(101) have changed and the changes for differentmaterials and treatments are not the same.The tensile strength and elastic modulus of TC4have a significant decline,andthe plasticity incread after cryogenic processing and cycle heat treatment.The unifoumity of TC4organization improved through cycle treatment and thegrains rotated with the appearing of texture phenomenon.Due to the compressioncreased by cryogenic,there are a lot precipitates and holes in the grain boundary.