Hot Deformation Behavior of Beta Titanium Ti-13V-11Cr-3Al Alloy
- PDF / 3,568,069 Bytes
- 11 Pages / 593.972 x 792 pts Page_size
- 60 Downloads / 172 Views
UCTION
BETA titanium alloys are high-tech materials that possess excellent workability and mechanical properties comparable to those of high strength steels.[1] They have been used widely in aero-engines due to their excellent properties such as low density, high temperature strength, and hot corrosion resistance.[2] Different heat treatment regimes can be used to change the microstructure of these materials and obtain a wide range of mechanical properties.[3,4] In addition, titanium alloys may be thermo-mechanically processed (TMP) to achieve a good combination of high strength and toughness.[5,6] The initial bulk working of Ti alloys is often carried out in the stability range of the b-phase.[7] Dynamic softening processes in b facilitates obtaining heavy reductions and help achieve sound products.[8] In a-b alloys, some complementary working may be carried out below the beta transus temperature (Tb), in the twophase region, to modify the microstructure and improve mechanical properties.[9–11] Some of previous investigations have suggested that a lamellas tend to become globularized during hot deformation in the two-phase SEYED MEHDI ABBASI and MARYAM MORAKKABATI, Academic Staffs, and AMIR HOSSEIN SHEIKHALI, Student, are with the Advanced Materials Research Laboratory, Metallic Materials Department, AMR of Technology, Tehran, Iran. AMIR MOMENI, Academic Staff, is with the Department of Materials Science and Engineering, Hamedan University of Technology, Hamedan, Iran. Contact e-mail: [email protected] Manuscript submitted December 13, 2013. Article published online July 16, 2014 METALLURGICAL AND MATERIALS TRANSACTIONS A
region.[7,12] However, the behavior of b in duplex structures has not been clearly indicated. On this basis, characterizing the hot working behavior of single-phase or two-phase Ti alloys has been the topic of numerous investigations in the past decades.[7,13–15] In single-phase b alloys, dynamic recovery (DRV) is expected to be the controlling mechanism of microstructural evolution during hot deformation. However, in previous investigations, dynamic recrystallization (DRX) of this phase has also been reported in different alloys.[16–18] Although this is interesting from both scientific and industrial points of view, there has not been strong evidence about the influence of deformation condition on the mechanism of DRX in different b-Ti alloys. Recently, a continuous dynamic recrystallization (CDRX) mechanism has been found responsible for extensive grain refinement and good workability in a b-Ti alloy.[19] Although the idea of CDRX in b-Ti alloys has been suggested by some researchers,[11] others believe in a conventional discontinuous DRX (DDRX).[16] Therefore, more precise investigations are needed to settle the controversies over the mechanism of dynamic softening in b-Ti alloys. The aim of the present work was, therefore, to study the hot deformation behavior of beta alloy Ti-13V11Cr-3Al with a view to optimize its hot workability and achieve microstructural control during hot processing.
II.
EXP
Data Loading...
