Study On The Diffusion Behavior And Bonding Properties Of Interface Elements In Ti-Q235 Layered Composites Prepared By Asynchronous Rolling

Titanium steel layered composite material inherits the excellent mechanical properties of titanium and steel and the excellent corrosion resistance of titanium.It has wide application prospects in marine,chemical and nuclear power engineering fields.Therefore,it is of engineering significance to study the preparation process,interface and mechanical properties of titanium steel layered composites.In this paper,Ti-Q235-Ti and Ti-Cu-Q235-Cu-Ti two kinds of titanium steel layered composites were successfully prepared by the three-step method of"surface treatment+asymmetric cold rolling composite+diffusion annealing".The interfacial microstructure,interfacial bond strength and overall tensile mechanical properties of two layered composites aft er diffusion annealing were compared.According to the experimental results,the following conclusions were obtained:（1）According to the experimental experience,the optimal rolling composite process conditions are determined:symmetric composite;single pass asymmetric rolling composite;reduction of 45%-50%;preheating temperature 280℃-300℃;preheating time 6-10 minutes.（2）The uneven distribution of interfacial stress leads to a difference in the diffusion of interface element components under the same annealing condition.（3）The rolling bonding mechanism of Ti-Q235 interface,Ti-Cu interface and Cu-Q235 interface can be explained by thin film theory.（4）Ti-Q235 interface bonding is poor.As the annealing temperature and time increase,the interface defects decrease.Finally,the interface forms an oxide layer at a high temperature of 950℃.The oxide layer hinders the inter-diffusion of Ti and Fe.（5）The combination of Ti-Cu interface and Cu-Q235 interface is better.According to EDS and XRD analysis,it was confirmed that a Ti-Cu binary intermetallic compound was formed at the Ti-Cu interface during diffusion annealing.The growth of the diffusion layer obeys the law of parabolic growth.According to the energy spectrum data and the effective h eat generation principle,the types and order of formation of intermetallic compounds were analyzed:CuTi,Cu₄Ti,Cu₄Ti₃,CuTi₂,Cu₂Ti.（6）The mechanical properties,macroscopic and micro fracture morphology of the two layered composites were analyzed com prehensively.The effect of the Cu intermediate layer on the bonding strength of the composites was qualitatively described.Finally,the optimal preparation process parameters of the layered composites are determined:add copper intermediate layer;single pass asymmetric rolling composite;45%-50%reduction;preheating temperature 280℃-300℃,preheating time 6-10 min;annealing at 750℃/1h with argon gas protection.