Balancing of mechanical properties of Ti-4.5Fe-7.2Cr-3.0Al using thermomechanical processing and rapid heat treatment

Abstract

Effects of new thermomechanical treatment, which includes consecutive solid solution, cold deformation and rapid recrystallization (SSCDRR), and final aging on microstructure and mechanical properties of the Ti-4.5Fe-7.2Cr-3.0Al alloy was investigated employing optical and electron transmission microscopy, tensile and fatigue testing. Beta grain size fell below 100 μm by hot deformation at a temperature within the two-phase α + β field and subsequent rapid heating up to 1123 K at 20 Ks-1. Further refinement of β grain microstructure up to average grain size of about 7 μm become possible by cold deformation and rapid heating up to 1013-1043 K at 20 Ks -1 or 1023-1063 K at 50 Ks-1. Tensile strength of the fine β-grain specimens increased by aging, up to 1840-1412 MPa while ductility can be varied within rather wide range by changing β-grain size as a result of controlled SSCDRR. Thus, the desired balance between strength and ductility may be achieved by optimizing treatment parameters. ©2005 The Japan Institute of Metals.