Effect of Solution Temperature on the Microstructure and Mechanical Properties of a Newly Developed Superalloy TMW-4M3

Abstract

The influence of solution temperature on the microstructure and mechanical properties of TMW-4M3 superalloy has been investigated. Comparisons of mechanical properties have also been made between the heat-treated TMW-4M3 variants and the commercial U720Li. The key microstructural variables examined were grain size and the volume fraction and size of the strengthening c¢ precipitates that control the mechanical properties of these alloys. By increasing the solution temperature from 1373 K to 1393 K (1100°C to 1120°C), the volume fraction of primary gamma prime dropped from 16.9 pct to 14.5 pct, whereas the average grain size increased from 8.7 lm to 10.6 lm. Compared with an alloy with a smaller grain size, the alloy with a larger grain size exhibited superior resistances to creep and fatigue crack growth without the expense of reduced tensile strength and low-cycle fatigue resistance. This suggested that a higher solution temperature may benefit TMW-4M3 in terms of superior overall properties. The greater overall properties of TMW-4M3 variants than that of commercial U720Li were also demonstrated experimentally. The possible explanations for the improvement of mechanical properties were discussed.

Refining Micron-Sized Grains to Nanoscale in Ni-Co Based Superalloy by Quasistatical Compressive Deformation at High Temperature

“…In this study, when the samples were deformed at lower strain and 725 • C, {111} <110> slip system was activated subsequently, then the a/2 <110> full dislocations dissociated into a/3 <112> Frank partial dislocation and a/6 <112> Shockley partial dislocation to facilitate the dislocation motion in face-centered cubic (FCC) metals [24]. Though the slipping dislocations could pass across fine secondary γ precipitates by a shearing mechanism, they would be impeded and piled up by larger primary γ precipitates unless dislocation climbing was activated.…”

The synchronous improvement of strength and plasticity (SISP) in new Ni-Co based disc superalloys by controling stacking fault energy

“…However, some inevitable shortcomings are also introduced by these strengthening mechanisms, such as element segregation, rapid dislocation recovery and grain boundary oxidization, which will counteract the strengthening effect and diminish the plasticity 1 , 5 , 6 . Though increasing γ′ content and decreasing γ′ size can improve the strength in superalloy, the plasticity and hot workability will deteriorate consequently when the γ′ content exceeds 50% 7 . Considering the limits of these conventional approaches, developing an alternative way to enhance the strength without the loss of ductility is becoming extremely important.…”