Time-Dependent Fatigue Crack Propagation Behavior of Two Solid-Solution-Strengthened Ni-Based Superalloys—INCONEL 617 and HAYNES 230

The fatigue crack propagation (FCP) as well as the sustained loading crack growth (SLCG) behavior of two solid-solution-strengthened Ni-based superalloys, INCONEL 617 (Special Metals Corporation Family of Companies) and HAYNES 230 (Haynes International, Inc., Kokomo, IN), were studied at increased temperatures in laboratory air under a constant stress-intensity- factor (K) condition. The crack propagation tests were conducted using a baseline cyclic triangular waveform with a frequency of 1 3 Hz. Various hold times were imposed at the maximum load of a fatigue cycle to study the hold time effect. The results show that a linear elastic fracture mechanics (LEFM) parameter, stress intensity factor (K), is sufficient to describe the FCP and SLCG behavior at the testing temperatures ranging from 873 K to 1073 K (600 C to 800 C). As observed in the precipitation-strengthened superalloys, both INCONEL 617 and HAYNES 230 exhibited the time-dependent FCP, steady SLCG behavior, and existence of a damage zone ahead of crack tip. A thermodynamic equation was adapted to correlate the SLCG rates to determine thermal activation energy. The fracture modes associated with crack propagation behavior were discussed, and the mechanism of time-dependent FCP as well as SLCG was identified. Compared with INCONEL 617, the lower crack propagation rates of HAYNES 230 under the time-dependent condition were ascribed to the different fracture mode and the presence of numerous W-rich M6C-type and Cr-rich M23C6-type carbides. Toward the end, a phenomenological model was employed to correlate the FCP rates at cycle/time-dependent FCP domain. All the results suggest that an environmental factor, the stress assisted grain boundary oxygen embrittlement (SAGBOE) mechanism, is mainly responsible for the accelerated time dependent FCP rates of INCONEL 617 and HAYNES 230

Role of oral care to prevent VAP in mechanically ventilated Intensive Care Unit patients

Ventilator associated pneumonia (VAP) is the most common nosocomial infection in Intensive Care Unit. One major factor causing VAP is the aspiration of oral colonization because of poor oral care practices. We feel the role of simple measure like oral care is neglected, despite the ample evidence of it being instrumental in preventing VAP

Studies on Early Podding Varieties and Post-Harvest Management of Immature Green Grains of Chickpea to be Used as Vegetable

The experiments were conducted on short-duration chickpea genotypes and post-harvest management of green grains for expanding the period of green grain availability in northern India. Two super-early chickpea breeding lines, ICCV 96029 and ICCV 96030, developed at ICRISAT were evaluated for green grain yield and other ancillary characters. Both lines were found early in flowering and podding and produced >2.0 t ha-1 fresh green seed yield in 75 days after sowing when sown in first week of October. Though the early podding lines could make available green grains for a longer period, the acceptability of these lines was restricted due to their susceptibility to diseases and less-preferred pale yellowish grain color. Hence, efforts were made to improve these traits by crossing super-early lines with well adapted cultivars/elite lines. Over 260 progenies (F4 to F6) were evaluated along with checks ICCV 96030 and PBG 1 during crop season 2005/06. Many progenies were found superior to the best check ICCV 96030 and selected for further evaluation. Experiments conducted on different packaging and storage methods showed that green grains and pods packed with/without peduncles in polyethylene (PE) packs in presence/absence of CaCl2 extended the shelf life. In PE packs, green grains without CaCl2 in thermocol box could be stored for up to 15 days at refrigeration temperature. Green pods showed better shelf life than shelled green grains. Acetic acid solutions with salt solutions could be used to enhance the shelf life of green grains. Thus, the early podding varieties can be used for expanding the availability of green grains and the storage methods identified in this study can be used for extending shelf life of green pods/grains of chickpe

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