Effect of heat treatment temperature on microstructure and mechanical properties of Mo–14Re alloy tubes

The effects of heat treatment temperatures on the microstructure and mechanical properties of Mo–14Re alloy tubes after the vacuum annealing were studied in this paper. The results show that, the grains of Mo–14Re alloy tubes after rolling are elongated along the rolling direction, showing the obvious fiber structure, and the grains are locally widened after the heat treatment at 1100 ℃. With the increase of heat treatment temperature, the grains of Mo–14Re alloy tubes are completely recrystallized at 1300 ℃. The Mo–14Re alloy tubes show the excellent combination of strength and plasticity at 1100 ℃ for 1 h, the tensile strength is 710 MPa, and the elongation is 36.5%. In the fracture analysis, it is found that the Mo–14Re alloy tubes have the wood grain tearing fracture at the annealing temperature below 1100 ℃, showing the obvious plastic deformation characteristics. However, when the heat treatment temperature is increased to 1300 ℃, the fracture is quasi-cleavage due to the recrystallization, and the plastic deformation is mainly caused by grain boundary slip. Comprehensive analysis shows that the optimal heat treatment temperature of Mo–14Re alloy rolling tubes should be controlled between 1100 ℃ and 1300 ℃.