The Effects of Filler Types on the Microstructure and Mechanical Properties of Ti-6Al-4V/316L Stainless Steel Joints Produced with Vacuum Brazing
摘要
This study investigates the effects of three brazing fillers, including AgCuTi, amorphous Ti-based, and amorphous Zr-based fillers, on the various properties of the joints between Ti-6Al-4V and 316L stainless steel. In this regard, the brazing was conducted at two temperatures of 900 °C and 950 °C for 30 min. The microstructure and the mechanical properties of the samples were analyzed using optical microscopy, scanning electron microscopy, x-ray diffraction, shear strength, and microhardness tests. Results showed that using AgCuTi filler at 900 °C, the microstructure of the brazed area included the layers of Ti2Cu, an Ag-based solid solution, and Fe3Ti. However, increasing the brazing temperature to 950 °C eliminated the Ag-based solid solution and increased the thickness of the Ti2Cu reaction layers. In contrast, the brazed joints produced with Ti- and Zr-based fillers displayed almost similar microstructure when the temperature increased. The reaction layer thickness for these fillers was notably less than that of AgCuTi samples (2 vs. 8-12 µm). The joints produced with AgCuTi fillers showed the lowest microhardness of 154 HV at 900 °C. Moreover, the corresponding value for all samples increased with temperature, and the highest hardness of 793 HV was achieved with Ti-based fillers at 950 °C. The highest shear strength value of 218.8 MPa was also obtained for the samples brazed with Ti-based filler at 950 °C which was about 8.04% and 2.8 times higher than the corresponding values calculated for the samples brazed with Zr-abased filler (202.5 MPa) and AgCuTi (78.6 MPa) at 950 °C.
Graphical Abstract