Material Properties of Newly Developed Heat Resistant Titanium Alloy “Ti‐1Cu‐1Sn‐0.35Si‐0.2Nb” for Automotive Exhaust Applications

Abstract

To respond to increasing demand for the use of light weight titanium alloys at high temperature in the automotive exhaust systems, a new alloy "Ti-1Cu-1Sn-0.35Si-0.2Nb (10CSSN)" has been developed with emphasis on high-temperature strength, which should be higher than that in previously developed Ti-1Cu-0.5Nb. The new alloy was designed to utilize solid solution strengthening of Si and Sn in addition to Cu, and to utilize advantageous effects of Si and Nb against high-temperature oxidation. Major mechanical properties of 0.9-1.15mm thick 10CSSN sheets are as follows : Yield stress at 700ºC is approximately 1.5 times higher than Ti1Cu-0.5Nb, while room-temperature elongation, one of the indexes for formability, is approximately 30%, equivalent to Ti-1Cu-0.5Nb. Time required for 3% creep strain at 650ºC is considerably high compared to Ti-1Cu-0.5Nb. Oxidation resistance is equivalent to or higher than Ti-1Cu-0.5Nb at 600-800ºC, and high-temperature salt damage is greatly improved.

Recent Topics of Titanium Research and Development in Japan

“…Therefore, based on Ti-1Cu-0.5Nb, Ti-1Cu-1Sn-0.35Si-0.2Nb (CSSN) has been newly developed. Figure 36 [65] [66] [67] shows the tensile strength of CSSN and other materials at elevated temperatures along with those of CP JIS class-2, Ti-1Cu and Ti-1Cu-0.5Nb. The tensile strength of CSSN is the highest among all the alloys at all temperatures.…”