Laser Oscillating Welding of TC31 High-Temperature Titanium Alloy

Zhimin Wang,Chunming Wang,Wei Yao,Zhi Zeng,Lulu Sun,Wenchao Ke

doi:10.3390/met10091185

Abstract

The joining of high-temperature titanium alloy is attracting much attention in aerospace applications. However, the defects are easily formed during laser welding of titanium alloys, which weakens the joint mechanical properties. In this work, laser oscillating welding was applied to join TC31 high-temperature titanium alloy. The weld appearance, microstructure and mechanical properties of the laser welds were investigated. The results show that sound joints were formed by using laser oscillating welding method, and a large amount of martensite was presented in the welds. High mechanical properties were achieved, which was approaching to (or even equaled) the strength of the base material. The joints exhibited a tensile strength of up to 1200 ± 10 MPa at room temperature and 638 ± 6 MPa at 923 K. Laser oscillating welding is beneficial to the repression of porosity for welding high-temperature titanium alloy.

Highlights

Titanium alloys exhibit high specific strength, excellent corrosion resistance and high thermal strength, which have been widely used in aerospace field to reduce weight [1,2,3,4]
The base metal is high-temperature titanium alloy TC31 in this study, and its composition and mechanical properties are listed in Tables 1 and 2, respectively
A large amount of acicular Ti and columnar prior β grain boundaries can be observed in the fusionprior zone β (FZ) as shown in Figure 7b,c, which implies that the prior β phase gradually transform into the secondary α phase [1,29]

Summary

Introduction

Titanium alloys exhibit high specific strength, excellent corrosion resistance and high thermal strength, which have been widely used in aerospace field to reduce weight [1,2,3,4]. High-temperature titanium alloys possess excellent mechanical properties at high temperature, and the service temperature of these alloys is increased to above 873 K [5,6,7] Due to these excellent performances, high-temperature titanium alloys have become advanced materials in aerospace applications, such as the components of aircraft engines, wings and rudders [8]. This alloy has good durability and creep properties under high load and high temperature [12] It has shown a prefect application in the aerospace field. To obtain a sound joint with good mechanical performance is a key factor to achieve structural integrity, light weight and low-cost manufacturing for its applications. High-temperature titanium alloy TC31 was welded by a laser oscillating welding method.

Experimental

Weld Appearance and Internal Quality

Microstructure Characterization

Magnification view fusion heat-affectedzone zone ofW5

Mechanical Properties

Conclusions