Microstructure and mechanical behavior of annealed MP35N alloy wire

Co-Cr-Ni-Mo wires for medical applications : processing, mechanical, microstructure and fatigue characterization

“…Prasad, M., et al [164,165] has conducted the annealing tests on a 0.102 mm diameter MP35N wires subjected to a temperature of 800 0 C and 900 0 C for a duration of 60 minutes as shown in Figure 2.29, and concluded that a change of microstructure from the as drawn condition was observed only after 900 0 C. For both annealing conditions, the crystallographic orientation in the longitudinal direction was almost random whereas, in the transverse direction along the cross-section of the wire, there was a strong presence of <111> fiber texture along with a significant fraction of the <100> component. The texture in the transverse direction after annealing has not significantly changed from the texture in the as-drawn condition although recrystallization and grain growth has been observed.…”

“…The S-N plot between the two alloy systems is shown in Figure 2.44, there was no significant difference observed in the high-stress amplitude region, but there was a shift in the S-N curve, with the material able to withstand to higher number of cycles to failure at lower stress amplitudes. This was accredited to the reduced inclusions in the Prasad et al [164,165], has studied the cyclic deformation response of the 0.101mm 35NLT wire as drawn and annealed wire, using a rotary beam bend fatigue (RBBF) and tension-tension fatigue (TTF) tests and concluded that the endurance limit for the material was < 500MPa for a fatigue life of 10 7 cycles. They also noticed that the sensitivity of the test method was more predominant in the LCF region when compared to the HCF region.…”

“…wire. [164,165] The fatigue life of the as-drawn wire deformed with RBBF test method was higher when compared to the TTF test method as shown in Figure 2.46, it can be also observed that the fatigue life of the as drawn wire was higher in the HCF region when compared to the annealed wire, and the fatigue life of the annealed wire was higher in the LCF region when compared to the as drawn wire, this was ascribed to the different Based on the observed findings as per discussions in the sections above, the following points can be summarized;…”

“…reported the cyclic behavior of the material tested under different applied stress and strain amplitudes [371], or with distinct test methods (tension-compression vs. tension-tension) [164], contributed to a diverse fatigue response in the material. SEM analysis was done on the fatigue specimens, to visualize and determine the mode of fracture [165]. However, there were no studies done on MP35NLT fine wires, investigating the influence of the manufacturing process and its relevant microstructure on the fatigue performance of the material.…”

“…OIM maps of the wire annealed at (a, c) 800C (b, d) 900C; (a, b) is in the transverse direction (c, d) is in the longitudinal direction[165] …”