Study on Aging Structure and Mechanical Properties of Low-cost β Titanium Alloy

According to the alloy design criteria with reference to Mo equivalent(Mo eq)and β phase stability coefficient(K_β), two low cost titanium alloys with nominal components of Ti-9Mo-4Cr-Fe-4.6Al (1^#) and Ti-9Mo-4Cr-Fe-4.6Al-0.3O(2^#)were designed.The microstructure and mechanical properties under as-cast and different aging conditions were studied.The microstructure of two alloys under different aging conditions were observed and analyzed by optical microscope(OM), scanning electron microscope (SEM) and X-ray diffraction (XRD).The Vickers hardness and compression properties were tested.The results show that 1^#and 2^#alloy have the best precipitation effect at 550 ℃/8 h and 520 ℃for 2-5 h respectively.The mechanical performance results are as follows:the maximum hardness of the two alloys after aging treatment are 608.83 HV10 and 650.35 HV10 respectively.The compressive yield strength and compressive strength of 1^#alloy are 1404 MPa and 1562 MPa respectively, the compression ratio is 9%.The compressive yield strength and compressive strength of 2^#alloy are 1405 MPa and 1561 MPa respectively, the compression ratio is 21%.Therefore, in order to obtain a excellent plasticity, the aging temperature of titanium alloy containing O should be selected at 520 ℃.