Study On Microalloying Of Boron And Silicon In Ti-1Al-8V-5Fe Alloy

In recent years,high-strength titanium alloys have been widely used in aerospace and other industrial fields,and have become an important research object for researchers both at home and abroad.As a brand of high strength titanium alloy,Ti-1Al-8V-5Fe(Ti185)hasmainly used in titanium alloy sheets,fasteners and connectorsdue to itshigh tensile strength and shear strength.In this experiment,the microstructure and properties of the alloy were further improved by adding alloying elements such as B and Si under vacuum melting conditions,and then the microstructure and mechanical properties of the alloy in the as-rolled state and the heat-treated state were systematically studied.The mass fraction of the B element added to the Ti-1Al-8V-5Fe alloy was 0.05wt%,0.1wt%,0.2wt%,and the mass fraction of the added Si element was 0.25wt%,0.5wt%,0.75wt%,respectively.The microstructure and mechanical properties of the as-rolled alloy after adding a small amount of alloying elements were studied.After adding B and Si elements with differing ratios,the best rolling mechanical properties of Ti-1Al-8V-5Fe-0.1B and Ti-1Al-8V-5Fe-0.5Si alloys were selected for heat treatment in different ways.The results show that the alloy with 0.1wt% B(Ti-1Al-8V-5Fe-0.1B)and 0.5wt% Si(Ti-1Al-8V-5Fe-0.5Si)rolled at 800 ? have the best mechanical properties with a tensilestrength of 1066 MPa and 794 MPa respectively.The tensile strain for these alloys are 11.13% and 10.31%respectively.As for heat treatment,insulting Ti-1Al-8V-5Fe-0.1B at 515? for 4 hours yielded the best mechanical properties: a tensile strength of 1389 MPa and the tensile strain of 4.51%.The tensile strength of the alloy shows a significant improvement after the heat treatment.The size of the precipitated alpha phase has also increased,with the strength and plastic of the allow decreasing with the aging temperature increments.Taking the rollingalloy of Ti-1Al-8V-5Fe-0.5Si for heat treatment at 560 ? for 4 hours yielded a tensile strength of 1226 MPa,and a tensile strain of 5.28%.At the same time,it?s also found that the alloy has the biggest strength(1669MPa)and poorest plasticwhen aged at 480 ?.With the increasing of aging temperature,the alloy?s strength is decreasing and the plasticity instead of increasing.With the increasing of holding time,alloy?s strength continued to fall and the plasticity increased first and then decreased during aging at 560 ?.