Microstructure and Mechanical Properties of Welded Joints of Titanium Alloy Ti60 after Laser Welding and Subsequent Heat Treatment

Abstract

The methods of scanning electron microscopy and x-ray diffractometry are used to study the microstructure and mechanical properties of welded joints from alloy Ti60 after laser welding and subsequent heat treatment (PWHT). It is shown that the microstructure of the welded joint consists of three zones, i.e., a fusion zone (FZ), a heat-affected zone (HAZ) and base metal (BM). The PWHT lowers considerably the hardness in the FZ and in the internal HAZ, which results in a more homogeneous hardness profile as compared to the post-welding condition. After the heat treatment, the ultimate strength of the welded joint is 980 MPa at room temperature and 728 MPa at 600°C, the elongation is 10.9% at room temperature and 18.3% at 600°C.