Ultra-high cycle fatigue life forecasting method of high-strength titanium alloy electron beam welding joint

Abstract

The invention discloses an ultra-high cycle fatigue life forecasting method of a high-strength titanium alloy electron beam welding joint. According to the method, ultra-high cycle fatigue performances of the high-strength titanium alloy electron beam welding joint are acquired by the aid of an ultrasonic fatigue test, electron beam welding defect size parameters are introduced based on nano-crackpropagation theories, an ultra-high cycle fatigue life loss equation is built, and ultra-high cycle fatigue service lives of high-strength titanium alloy welding structures of different electron beamwelding defects are quantitatively forecasted. The ultra-high cycle fatigue service life loss equation containing electron beam welding defect size parameters is built through the ultrasonic fatiguetest, electron beam welding defect sizes are acquired through metallographic profile or non-destructive inspection, and the ultra-high cycle fatigue service lives of the high-strength titanium alloy welding structures of different electron beam welding defects can be quantitatively forecasted. According to the method, a lot of ultra-high cycle fatigue tests of electron beam welding joints are avoided, ultra-high cycle fatigue service life assessment can be completed, and the method has the advantages of simplicity, rapidness and economical property.

Description

technical field [0001] The invention belongs to the technical field of non-ferrous metals, in particular to a method for predicting the ultra-high cycle fatigue life of a high-strength titanium alloy electron beam welded joint. Background technique [0002] High-strength titanium alloy has the advantages of high strength, light weight, high temperature resistance, corrosion resistance and excellent formability, and is widely used in aeronautical structures, aeroengine compressor blades, steam turbine blades and other fields. Titanium alloy structural components are often formed by electron beam welding, which can withstand high-frequency vibration fatigue loads during high-speed operation, and can withstand cyclic loads of up to 10 during long-term service. 9 Week times, that is, ultra-high cycle fatigue. This welding method has a high specific energy and a small heat-affected zone of the weld, but defects such as welding pores are still unavoidable, and ultra-high cycle fa...

AI Technical Summary

Problems solved by technology

[0003] For ultra-high-cycle fatigue of high-strength titanium alloy electron beam welded joints, ultra-high-cycle fatigue cracks initiate in welding pores, expand discontinuously at the nanoscale, and form fine-grained regions. Fatigue damage is a nonlinear damage feature, but the current nonlinear life The loss equation is mainly phenomenological and does not directly reflect the size of electron beam welding defects. Therefore, the current life model cannot accurately predict the ultra-high cycle fatigue life of high-strength titanium alloy electron beam welding structures.

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