Improved Single Crystal Superalloys, CMSX-4 (SLS)[La+Y] and CMSX-486

Abstract

Single crystal superalloys and casting technology offer a combination of attractive properties for advanced gas turbine engine components. The alloys are designed to produce superior properties for a challenging combination of requirements: high temperature creep-strength, fatigue resistance, oxidation resistance, coating performance and retention of performance in thin-walled configurations. Application of this technology to new components has only been restricted by the competing criteria of affordability for first time introduction.The development of improved single crystal superalloys, CMSX-4 (SLS) [La+Y] and CMSX-486 provide an appealing combination of enhanced performance and production affordability for demanding, high temperature applications in advanced gas turbine engines.

Stability of dendrite growth during directional solidification in the presence of a non-axial thermal field

“…The initial investigation employed CMSX-486. The nominal alloy composition (in wt.%) for CMSX-486 is Ni-9.3Co-8.6W-5.7Al-5.0Cr-4.5Ta-3Re-1.2Hf-0.7Mo-0.7Ti-0.07C-0.015B-0.005Zr [24]. A further investigation evaluated René-N4 in order to identify the dependence on the evolution of dendrite morphology on alloy chemistry.…”

A New Single Crystal Superalloy for Power Generation Applications

“…The casting stock was melted by Ross & Catherall in Sheffield, UK to industry-leading standards. Chemical analysis indicated less than 7.2 ppmw of sulphur in the stock, so that -since the oxidation temperatures used here are 1000ºC or lower and the tests carried out isothermally -any influence of this element on oxidation performance will be negligible [9][10][11]. Casting was carried out under the vacuum of better than 10 -4 Pa.…”

Recent developments in gas turbine materials and technology and their implications for syngas firing

“…The SC variant (which has additions of Hf and B to reduce the sensitivity to the presence of casting defects) can be used in the as-cast condition, further contributing to a reduction in cost compared with the highest-strength SC alloys. Further progress [8] has led to development of the alloy CMSX-486, which also has additions of Hf and B to increase tolerance to casting defects, but is otherwise similar in composition to the second-generation alloy CMSX-4, see Table 2. An additional advantage of this alloy is that good high-temperature properties were obtained with a double aging treatment after casting, thereby eliminating the risk of localized recrystallization during solution heat treatment.…”

“…Some examples of typical creep properties of some SC alloys are given in Fig. 1 [8], where the stress for rupture in 1000 h is shown as a function of temperature. It will be seen that alloy TMS 162 has a temperature advantage of about 30-40 • C compared with the widely used CMSX-4.…”