Investigation of the Effect of Post Weld Heat Treatment on the Microstructure an‎d Mechanical properties of Friction Stir Welded CuZn39Pb2 alloy

10/21/2026 12:00:00 AM

The aim of this study is to investigate the effect of post-weld heat treatment on the microstructure an‎d mechanical properties of the CuZn39Pb2 alloy welded by friction stir welding (FSW). For this purpose, the welded specimens were subjected to various heat treatment temperatures of 250, 300, 450, 500, 600, an‎d 650 °C. Subsequently, tensile tests were performed at a crosshead speed of 1 mm/min perpendicular to the welding direction. The microstructure of the joint an‎d the fracture surface were examined using optical microscopy an‎d scanning electron microscopy (SEM). In addition, the phases formed were identified an‎d residual stress values were calculated using X-ray diffraction (XRD). The results showed that during friction stir welding, the weld zone consisted of fine dynamically recrystallized grains, which exhibited grain growth with increasing heat treatment temperature. Accordingly, the size of the α phase increased from 8.06 µm in the as-welded sample to 10.25 µm in the sample heat-treated at 650 °C. Moreover, increasing the heat treatment temperature up to 650 °C led to an increase in the volume fraction of the β′ phase from 38.4% to 48.5%. The reduction in the volume fraction of the α phase was further confirmed by the disappearance of the corresponding α-phase peak in the XRD patterns. Mechanical investigations indicated that increasing the heat treatment temperature resulted in a decrease in tensile strength an‎d an increase in elongation. Residual stress analysis also showed that with increasing heat treatment temperature, the residual stress in the welded sample decreased from +50 MPa to +14 MPa. Hardness testing revealed a reduction in hardness with increasing annealing temperature due to grain growth, such that the average hardness of the as-welded sample was 135 HV, while that of the sample heat-treated at 650 °C was 116 HV. Fracture surface analysis demonstrated that fracture in the non–heat-treated sample was predominantly brittle. However, with increasing heat treatment temperature, the brittleness of the fracture surface decreased, an‎d the number of dimples in the joint cross-section increased, indicating a transition to ductile fracture behavior.

جوشكاري اصطكاكي همزني , جوشكاري برنج , جوشكاري اصطكاكي برنج , تنش پسماند , ريزساختار , ريزساختار

Friction Stir Welding , Brass Welding , Friction Welding of Brass , Residual Stress , Microstructure , Mechanical Properties

Mohadeseh Dadshahi

Ali Reza Eivani