Anisotropic Stress Rupture Properties of a 3rd-Generation Nickel-Based Single-Crystal Superalloy at 1100 °C/150 MPa

Abstract

The influence of orientation on the stress rupture behaviors of a 3rd-generation nickel-based single-crystal superalloy was investigated at 1100 °C/150 MPa. It is found that the stress rupture anisotropy is shown at 1100 °C, but not so obvious compared with that at intermediate temperatures. The [001] specimens display the longest rupture life, [111] specimens show the shortest rupture life, and [011] specimens exhibit the intermediate life. Detailed observations show that the final fracture is caused by crack initiation and propagation, and the anisotropy of three oriented specimens is related to the fracture modes, γ/γʹ microstructures, interfacial dislocation networks and cutting mechanisms in γʹ phase. For [001] specimens, N-type rafted structures are formed which can well hinder the slip and climb of dislocations. Besides, the regular interfacial dislocation networks can prevent dislocations from cutting into γʹ phase, leading to the improvement of the creep resistance. For [011] specimens, ± 45° rafted structures and irregular networks result in less strain hardening. For [111] specimens, a large number of crack propagation paths and inhomogeneous deformations caused by irregular rafted structures deteriorate the property and result in the shortest life. Furthermore, a[100] superdislocations with low mobility are widely formed in [001] and [011] specimens which suggests the low creep strain rate during steady creep stage, whereas superdislocations in [111] specimens possess high mobility, which indicates the high strain rate and corresponding poor stress rupture property.

Creep of High-Strength Steel Coated with Plasma Sprayed Self-Fluxing Alloy

“…The results agree with the morphology of the fracture surface defined in the work of Ranieri that assess the behavior of plasma nitrided 4340 Steel [37]. In plasma nitrocarburizing coating work on AISI 4340 steel, performed by Li et al, the creep failure morphology showed a similar aspect with microcavities and ductile fracture, both in coated and uncoated conditions [38]. The coated specimens show good adhesion to almost the entire perimeter of the sample under conditions of 200 and 250 MPa, with partial detachment in some areas.…”

Creep life prediction of Ni‐based single‐crystal superalloy plate with film‐cooling holes using a modified critical distance method based on the improved weight function

“…Therefore, Ni-based single-crystal superalloys with excellent high-temperature performance are widely used in the manufacturing of turbine blades. 1,2 However, in the actual operational process of turbine blades, relying solely on the material's temperaturebearing capacity falls far short of meeting the extreme temperature requirements. According to statistics, the improvement of high-temperature alloys and their manufacturing processes only contributes 30% to the increase in inlet temperature, while the other 70% benefits from the improvement of cooling mechanisms.…”

“…As the core component of the aircraft engine, the high‐temperature bearing capacity of the turbine blade is a key factor that restricts the increase in inlet temperature. Therefore, Ni‐based single‐crystal superalloys with excellent high‐temperature performance are widely used in the manufacturing of turbine blades 1,2 . However, in the actual operational process of turbine blades, relying solely on the material's temperature‐bearing capacity falls far short of meeting the extreme temperature requirements.…”

Modeling on the Fluid Flow and Mixing Phenomena in a RH Steel Degasser with Oval Down‐Leg Snorkel

“…Many investigations have proved that a lower vacuum pressure, a larger snorkels sectional area, [24,37] a deeper immersion depth, [14,38] and bottom blowing [13,16] would favor to optimize the fluid flow in RH. Recently, some researchers have tried to improve the refining efficiency by using single-leg, [28,34] some multi-legs [9,15,39,40] snorkel and magnetic field [30,41] surround the snorkels. However, the multileg and the rotating magnetic field were hardly used some time in the actual industrial manufacture considering the cost issue.…”