Simulation And Verification Of The Microstructure Of TC4 Titanium Alloy Bolts During Solution Aging Heat Treatment

TC4 titanium alloy material is widely used in aerospace,shipbuilding,chemical industry,and other fields due to its excellent corrosion resistance,good toughness,high specific strength,and low density.However,TC4 titanium alloy has high deformation resistance,poor plasticity,complex process,difficult processing,and high cost,which limits its improvement in mechanical properties.This article takes TC4 titanium alloy bolts as the research object,simulates and studies the heat treatment process,analyzes the relationship between their microstructure transformation characteristics and mechanical properties,and conducts a comprehensive analysis of the bolt’s various positions α and β The analysis of phase content provides a theoretical basis for optimizing the heat treatment system and formulating the heat treatment process of TC4 titanium alloy bolts.The main research content and conclusions of the paper are as follows:(1)Based on DSC and thermal expansion tests,a phase transformation kinetics model for the cooling process of TC4 titanium alloy was established and validated;(2)Based on the hot compression test,a flow stress model based on phase change was established and the accuracy of the flow stress model was verified;(3)A finite element model of TC4 titanium alloy bolts was established and finite element analysis of heat treatment was conducted.It was found that the higher the solid solution temperature of TC4 titanium alloy,α The lower the phase content,the higher the aging temperature,αThe higher the phase content;The temperature distribution at the core of TC4 titanium alloy bolts is uniform,with slow changes and high degree of phase transformation.The edge of TC4 titanium alloy nut is in direct contact with the medium,resulting in significant temperature changes and low degree of phase transformation;The roll R position and the center of the bolt head are between the two;(4)The microstructure and mechanical properties of TC4 during solution aging were analyzed by means of metallography,SEM and shear test,and the transformation law simulated by finite element was verified.Considering the factors of shear strength β The solid solution temperature at the phase transition temperature point,close to α The aging temperature of the phase transition point temperature is the optimal choice.