More and more titanium alloy and composite materials are used in advanced aircraft and spacecraft at home and abroad, and the amount of titanium alloy fasteners used as composite connectors is also increasing. Compared with alloy steel fasteners, titanium alloy has a significant weight reduction effect, and excellent corrosion resistance, especially the positive potential is exactly matched with carbon fiber composite materials, effectively preventing the galvanic corrosion of fasteners. In addition, titanium alloy also has good elasticity and non-magnetism, which is of great significance to prevent fasteners from loosening and magnetic field interference.
Ti45Nb alloy is a kind of riveting material used in aerospace field, which has the characteristics of high plasticity and excellent cold working performance. Ti45Nb alloy shear strength and tensile strength are higher than pure titanium, deformation resistance is lower than pure titanium, is the best choice of composite rivets. Ti45Nb rivets are mainly used in high temperature areas such as the side strip of the rear machine and the tail cover. Due to its excellent cold processing performance, high-speed continuous cold heading preparation and cold riveting of rivets can be completely realized, and TB2, pure titanium rivets that need to be heated riveted can be replaced.
Due to the low deformation resistance, the surface of the alloy is easily scratched, and the quality control of the surface of the wire is difficult. The continuous cold heading process of Ti45Nb rivet requires high surface quality and dimensional accuracy of the wire. Poor surface quality and low precision of the wire will cause rivet surface strain and die sticking during the cold heading process.
The preparation method of Ti45Nb alloy disc wire is to control the structure, properties and consistency of the wire through cold rolling, cold continuous rolling, cumulative cold deformation and intermediate annealing. The dimensional accuracy of material type and wire is controlled by cold rolling pass, cold tandem pass, roll die drawing pass and pass deformation. The Ti45Nb wire prepared by the invention has the roundness of the head, middle and tail of each roll in the whole batch, the surface roughness Ra≤1.2μm, no scratch and other surface defects, and the wire is qualified for eddy current inspection. After vacuum heat treatment, the finished wire sample has stable performance and meets the material standard requirements for corresponding fasteners. The transverse and longitudinal structure is fine and uniform, the grain size is above 5, and the longitudinal flow line is obvious.
