Effects of thermal undercooling and thermal cycles on the grain and microstructure evolution of TC17 titanium alloy repaired by wire arc additive manufacturing

Yimin Zhuo,Chenglei Fan,Sanbao Lin,Chunli Yang

doi:10.1007/s00170-021-08445-w

Abstract

Wire arc additive manufacturing (WAAM) can be used to repair blades or blisk made of titanium alloy with the advantage of high efficiency and low-cost. In this work, the finite element model of repairing the blade based on the arc heat source was established to investigate it. Results showed that the maximum effect of thermal undercooling appeared when the peak current transformed to the base current (1 Hz or 5 Hz), which will promote the grains refinement with the combination of sufficient constitutional supercooling. Compared to the single-layer deposition, the microstructure in the near-heat affected zone (near-HAZ) of multi-layer deposition changes from the metastable β phases to the extremely fine α phases, which was caused by the repeated thermal cycles.

Highlights

The development process of aero-engine is mainly the improvement process of thrust-weight ratio [1]
Results showed that the maximum effect of thermal undercooling appears when the peak current transforms to the base current (1Hz or 5Hz), which will promote the grains refinement with the combination of sufficient constitutional supercooling
Compared to the single-layer deposition, the microstructure in the near-heat affected zone of multi-layer deposition changes from the metastable β phases to the extremely fine α phases, which was caused by the repeated thermal cycles

Summary

Introduction

The development process of aero-engine is mainly the improvement process of thrust-weight ratio [1]. For the damaged blade with surface cracks, conventional brazing [5, 6] and wide gap braze [7,8,9] are recommended. These methods have the advantages of no jigging, no pressure required, and batch processability. According to our previous study [22], the feasibility of repairing the damaged blade by the WAAM technology was verified. The temperature cycle feature of the multi-layer repairing deposition based on the arc heat source needs to be further studied. The finite element model of repairing the blade based on the arc heat source was established. The triggering condition and effect position of thermal undercooling was discussed in detail

Experimental setup

And Discussion

Conclusions