Oscillating wire arc additive manufacture of rocket motor bimetallic conical shell

Tianying He,Shengfu Yu,Yu Runzhen,Zheng Bo

doi:10.1007/s00170-021-08477-2

Abstract

This paper studies the temperature field, dynamic strain, and forming accuracy of the oscillate-WAAM conical shell in the forming process and manufactures the WAAM conical shell part. The results show that compared with the offset filling WAAM, the oscillate-WAAM conical shell shows the following characteristics: the temperature difference value between the inner and outer walls of the shell is significantly reduced, the cooling rate doubled decreased, the interlayer temperature is above 300 °C, and the average temperature gradient, the dynamic strain stability value, and deformation are reduced by about 50%. Under the same process parameters, the travel speed of oscillate-WAAM is low, which increased the heat input large and the interlayer temperature high. Meanwhile, the molten pool of oscillate-WAAM is in consistent with the width of the shell. The molten pool’s simultaneous solidifying changes the stress state of printed shell from three-dimensional to two-dimensional. All the above are conductive to stress release and reduce the strain and deformation of components. The bimetallic rocket motor shell composed of HS600 and HS950 is manufactured by oscillate-WAAM. The section roundness of the shell is 0.31 mm, and the overall forming accuracy is ± 0.625 mm. The deposited metal in HS600 part of conical shell is composed of pearlite and pro-eutectoid ferrite, while the deposited metal of HS950 is composed of pearlite, acicular ferrite, and bainite. The forming accuracy and mechanical properties of conical shell formed by oscillate-WAAM meet the requirements.

Highlights

The conical shells are widely used in aerospace field, serving under severe environment of high temperature and high pressure
This paper studies the temperature field, dynamic strain and forming accuracy of the Oscillate-Wire arc additive manufacture (WAAM) conical shell in the forming process and manufactures the WAAM conical shell part
The results show that compared with the offset filling WAAM, the oscillate-WAAM conical shell shows the following characteristics:the temperature difference value between the inner and outer walls of the shell is significantly reduced, the cooling rate doubled decreased, the interlayer temperature is above 300°C, as well as the average temperature gradient, the dynamic strain stability value and deformation are reduced by about 50%

Summary

Introduction

The conical shells are widely used in aerospace field, serving under severe environment of high temperature and high pressure. The path planning determines the movement of heat source in WAAM, which changes the temperature field and strain curve of the shell, a key factor affecting its overall forming accuracy and mechanical properties [8,9,10]. The existing research results show that the oscillate-WAAM can improve the forming accuracy and mechanical properties of components, and reduce the number of overlaps formed by a single layer, as well as avoiding overlap accumulated errors and defects. The research of WAAM temperature field and stress field are focused on the straight-walled or circular ring components formed by multi-layer multi-pass overlapping methods. An oscillate-WAAM rocket motor bimetallic conical shell is manufactured, further its forming accuracy and mechanical properties are evaluated

Experimental Materials And Methods

Temperature field and thermal cycle of Oscillating WAAM

Deformation of Oscillating WAAM

Conical Shell Oscillating Waam Forming

Findings

Conclusions