Corrosion Behavior of Pure Titanium by MIM Process under SSRT Condition

Abstract

There exist difficulties in preparing pure titanium or titanium alloys by the ingot metallurgy (I/M) because of their poor machinability. Recently, powder metallurgy (P/M) has been applied to produce the titanium products since it has the advantage of better formability. There are, however, still some significant issues concerned in fabricating three dimensional complex shape products by the above mentioned conventional P/M process. Metal injection molding (MIM) process has the advantage of better formability of three dimensional complex shape products with high density and high performance properties. Two kinds of pure titanium specimens, i.e., the first one is prepared by the I/M process and the second one is prepared by MIM process are used in this experiment, and their corrosion behavior under stress has been investigated in several aqueous solutions by Slow Strain Rate Tensile (SSRT) test. Both I/M and MIM specimens showed good corrosion resistance in the aqueous solution composed of 2.5 kmol/m3 H2SO4 and 0.2 kmol/m3 NaCl as well as saline solution. This aqueous solution is noted one in which Type 304 stainless steel showed SCC. In the aqueous solution composed of CH3OH and 0.1 kmol/m3 HCl containing 8.6kg/m3 H2O, the elongation of MIM specimen was slightly higher than that of I/M specimen though both specimens indicated the remarkable decrease in elongation.