Study On The Effect Of Oxygen Contents On Hot Deformation Behavior And Mechanical Properties Of Hot Forged Structure Of TA31 Alloy

As the most common impurity element,Oxygen has a significant effect on the processing and mechanical properties of titanium alloy.Therefore,it is of great significance to study the effect of oxygen content on the thermal deformation process of TA31 alloy and the mechanical properties of hot forging TA31 alloy.By strictly controlling the content of impurity elements,especially oxygen,in the raw material of the alloy smelting process and adding TiO₂,an ingot having different oxygen content required for the experiment is smelted.The as-cast microstructures of Ti-6Al-3Nb-2Zr-1Mo titanium alloys with different oxygen contents were subjected to thermal simulation experiments on a Gleeble-3800 thermal simulation tester.The stress-strain curves of hot compression deformation at different temperatures and deformation rates were obtained.The eigen equation and hot deformation structure of Ti-6Al-3Nb-2Zr-1Mo titanium alloy with oxygen content of 0.04%and 0.14%?mass fraction?were obtained by analyzing and calculating the thermal deformation stress-strain curves.After observation,it was found that increasing the oxygen element will significantly increase the activation energy of the alloy's thermal deformation and inhibit the deformation of the alloy;but the proper oxygen content can promote the dynamic recrystallization of the alloy,so that the temperature required for dynamic recrystallization will decrease,and recrystallization will occur.The rate of deformation has also increased.Therefore,the processing temperature and deformation rate range of the titanium alloy hot deformation process can be broadened,and the dynamic recrystallization nucleation of the titanium alloy can be promoted.However,excessive oxygen content can also cause the rheological instability during the process of alloy hot deformation,resulting in a smaller processing area.Therefore,in the industrial production process,it is necessary to control the content of oxygen in the alloy in a reasonable range according to the specific thermal processing technology,so as to obtain more excellent overall performance.We studied how oxygen addition influences microstructures and mechanical properties of Ti-6Al-3Nb-2Zr-1Mo alloys.Oxygen greatly affects microstructure and improves mechanical properties of forged Ti-6Al-3Nb-2Zr-1Mo alloys.Oxygen content was controlled by adding TiO₂ to raw materials,which were then used to prepare series forged bars consisting of Ti-6Al-3Nb-2Zr-1-Mo-xO?x=0.042,0.07,0.0966,0.11,0.14,0.2,0.3,0.4,0.5,1 wt.%?cast alloys.These bars were tested,and the data was used to characterize and calculate how oxygen content affects strengthening mechanism of these alloys.Microstructure analysis demonstrated that oxygen addition significantly reduces grain sizes after hot deformation.Thus,strengthening mechanism is related to the fine-grain strengthening effects.Oxygen effect on fracture toughness is discussed as well.