Influence of solid-solution treatment on mechanical properties of nickel-chromium-molybdenum alloy and analysis of its fracture

Optical microscope, X-ray diffraction(XRD) and scanning electron microscope(SEM) were applied to investigate microstructure, phase-constituting, fracture morphology, mechanical properties of the hot-press nickel-chromium-molybdenum alloy before and after solid-solution treatment. The results show that the alloy after solid-(solution) treatment at (1 250 ℃/4 h) is Ni solid-solution, while the alloys before solid-solution treatment and after solid-solution treatment at 1 250 ℃/4 h also have Mo and some intermetallic compounds. The alloy after solid-solution treatment has higher tensile strength than that alloy before solid-solution treatment. The microstructure morphologies of the alloy after solid-solution treatment both at 1 200 ℃/4 h and (1 200 ℃/4 h) are ductile dimple, which are consistent with that of ductile fracture, but that of the alloy before solid-solution treatment is brittle cleavage, which is consistent with that of brittle fracture. The hardness before solid-solution treatment is higher than that after solid-solution treatment.