Creep Behavior and Damage of Ni-Base Superalloys PM 1000 and PM 3030

Abstract

Two oxide dispersion strengthening (ODS) nickel-base superalloys, a solely dispersionstrengthened alloy (PM 1000) and an additionally c¢-strengthened alloy (PM 3030) are investigated regarding creep resistance at temperatures between 600°C and 1000°C. The creep strength advantage of PM 3030 over PM 1000 decreases as the temperature increases due to the thermal instability of the c¢ phase. The particle strengthening contribution in both alloys increases linearly with load. However, solid solution softening leads to an apparent drop in particle strengthening in PM 1000. Deformation concentration in slip bands is more accentuated in PM 3030-R34 due to additional c¢ strengthening combined with strongly textured coarse and elongated grain structure. Finer, equiaxed grains reduce creep strength at higher temperatures due to grain boundary deformation processes and premature pore formation, but have only minor impact at low and intermediate temperatures.

Numerical assessment of blade deflection and elongation for improved monitoring of blade and TBC damage

“…However, it can be expected that more rapid creep deformation could be caused by the substantial substrate temperature rise resulting from TBC spallation. As creep is time dependent deformation that strongly depends on the blade temperature [48][49][50][51][52], an increase in accumulated blade elongation can be expected over time as a result of TBC spallation. Such an acceleration in creep would increase as the TBC defect is larger or located closer to the blade root where mechanical stresses are higher.…”

High‐Temperature Creep Properties of an Additively Manufactured Y2O3 Oxide Dispersion‐Strengthened Ni–Cr–Al–Ti γ/γ’ Superalloy

“…[ 2,4–6 ] This led to the development of ODS Ni‐based superalloys combining three types of strengthening (matrix solid solution, γ’ precipitates, and oxide dispersoid), such as MA6000 (Ni–15Cr–4.5Al–2.5Ti–4W–2Ta–2.5Fe–1.1Y 2 O 3 , wt%), PM3030 (Ni–17Cr–6Al–2Mo–3.5W–2Ta–0.9Y 2 O 3 ), and their variants. [ 7–11 ] The contributions of γ’ precipitates and oxide dispersoids to the creep resistance of these ODS alloys are found to be additive, making them superior to their solely precipitation‐hardened counterparts. [ 12 ] However, when the precipitates are then dissolved at high temperatures, similar creep resistance is observed again between γ’‐ and non‐γ’‐ strengthened ODS alloys, as only the dispersoids provide resistance to creep.…”

“…[ 12 ] However, when the precipitates are then dissolved at high temperatures, similar creep resistance is observed again between γ’‐ and non‐γ’‐ strengthened ODS alloys, as only the dispersoids provide resistance to creep. [ 8 ] Ultimately, ODS alloys provide superior performance compared with γ/γ’ Ni‐based superalloys only at medium stresses, at temperatures above γ’ coarsening or dissolution temperature and when high microstructural stability is required. [ 13 ] The need for additional strength at lower temperatures stems from applications where ODS alloys are desired for the hottest part of a component but still have to fulfill specifications in sections at lower temperatures.…”

Evaluation of Processing Conditions on the γ′ Morphology of an Oxide Dispersion Strengthened Ni‐Based Superalloy

“…[5][6][7][8][9][10] The typically yttrium-based oxide particles dispersed in the superalloy matrix are highly stable beyond 1000 C and promote the high-temperature performance of ODS superalloys. [11] Among the commercially available superalloys, MA6000 [12] and PM3030 [13,14] are examples of dual-phase grades of Ni-based ODS superalloys developed during the past decades.…”

“…One special category of Ni‐based superalloys has the advantage of secondary strengthening mechanism by dispersion of fine oxide particles, the so‐called “Ni‐based oxide dispersion strengthened (ODS) superalloys.” [ 5–10 ] The typically yttrium‐based oxide particles dispersed in the superalloy matrix are highly stable beyond 1000 °C and promote the high‐temperature performance of ODS superalloys. [ 11 ] Among the commercially available superalloys, MA6000 [ 12 ] and PM3030 [ 13,14 ] are examples of dual‐phase grades of Ni‐based ODS superalloys developed during the past decades.…”