Thermomechanical Properties and Stress Corrosion of RMI Ti-3A1-8V-6Cr-4Mo-4Zr

Abstract

RMI 38-6-44 is a newly developed beta titanium alloy of nominal composition, 3 percent aluminum, 8 percent vanadium, 6 percent chromium, 4 percent molybdenum, and 4 percent zirconium. This alloy can be easily worked at room temperature and combinations of mechanical working and thermal treatments produce a variety of complex microstructures. A broad range of engineering properties can be obtained as a result of these processes, This paper presents the procedures and results of a systematic investigation of the effects of various thermomechanical processes on the mechanical properties, corrosion resistance, susceptibility to stress corrosion and structure of this alloy. Investigations were conducted on material receiving 0 percent, 40 percent, and 80 percent cold work with no heat treating and material receiving zero percent, 40 percent, and 80 percent cold work and various heat treatments. Aging temperatures used were between 370–565°C for times varying from 15 minutes to 96 hours. Maximum yield strengths of 155 Kg/mm were obtained. A discussion of properties is presented and correlation between these properties and existing microstructures are discussed.